Co3O4-Bi2O3 heterojunction: An effective photocatalyst for photodegradation of rhodamine B dye

Muhammad Saeed; Norah Alwadai; Lamia Ben Farhat; Afifa Baig; Walid Nabgan; Munawar Iqbal

doi:10.1016/j.arabjc.2022.103732

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Original article

04 2022

:15;

103732

doi:

10.1016/j.arabjc.2022.103732

Co₃O₄-Bi₂O₃ heterojunction: An effective photocatalyst for photodegradation of rhodamine B dye

Muhammad Saeed^{^a,⁎}, Norah Alwadai^{^b,⁎}, Lamia Ben Farhat^{^c,^d}, Afifa Baig^{^a}, Walid Nabgan^{^e}, Munawar Iqbal^{^f}

a Department of Chemistry, Government College University Faisalabad, Pakistan

b Department of Physics, College of Sciences, Princess Nourah bint Abdulrahman University, P.O. Box 84428, Riyadh 11671, Saudi Arabia

c Department of Chemistry, College of Sciences, King Khalid University, P.O. Box 9004, Abha, Saudi Arabia

d Laboratoire des matériaux et de l'environnement pour le développement durable LR18ES10, 9 Avenue Dr.Zoheir Sai, 1006, Tunis, Tunisia

e School of Chemical and Energy Engineering, Faculty of Engineering, Universiti Teknologi Malaysia, Johor, Malaysia

f Department of Chemistry, The University of Lahore, Lahore, Pakistan

⁎Corresponding authors. msaeed@gcuf.edu.pk (Muhammad Saeed), nmalwadai@pnu.edu.sa (Norah Alwadai)

Received: 2021-11-26, Accepted: 2022-1-23,

Disclaimer:
This article was originally published by Elsevier and was migrated to Scientific Scholar after the change of Publisher.

Peer review under responsibility of King Saud University.

Abstract

Abstract

Recently, the research on the remediation of aqueous organic pollutants over visible-light-active photocatalysts has got much attention. Therefore, this study reports the fabrication of visible-light-active Co₃O₄-Bi₂O₃ heterojunction photocatalyst for the photodegradation of rhodamine B dye. The Co₃O₄-Bi₂O₃ heterojunction was synthesized by the coprecipitation method and characterized by XRD, EDS, SEM, TEM, TGA, and FTIR. The as-prepared Co₃O₄-Bi₂O₃ heterojunction was utilized as a photocatalyst for the abatement of rhodamine B dye. It was observed that Co₃O₄-Bi₂O₃ showed the best catalytic performance with ∼92% degradation of rhodamine B dye than Co₃O₄ and Bi₂O₃ with 14 and 34% removal of rhodamine B dye, respectively. The rate constant for Co₃O₄-Bi₂O₃ catalyzed photodegradation of rhodamine B was 6 times and 3 times higher than the rate constant for Co₃O₄ catalyzed and Bi₂O₃ catalyzed photodegradation of rhodamine B, respectively. The as-prepared Co₃O₄-Bi₂O₃ exhibited the highest catalytic performance at pH 8.

Keywords

Co3O4-Bi2O3

Heterojunction

Photodegradation

Rhodamine B

Kinetics analysis

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1 Introduction

The industrial revolution has not only extended the land to mitigate overbuilding but also contributed significantly to environmental pollution (Lo Piccolo and Landi, 2021). The textile industry is one of the industries that pollute the aqueous system due to the discharge of its dyes contaminated wastewater. Several techniques have been proposed for the abatement of wastewater. The removal of organic pollutants from an aqueous system by photocatalysis employing semiconductor metal oxides as photocatalysts play a crucial role in the treatment of wastewater due to its advantages of mild reaction conditions, complete mineralization of pollutants, and low processing cost (S. Li et al., 2017; S. Li et al., 2020b; Chen et al., 2018a; Meng et al., 2019 ). An ideal photocatalyst for photodegradation of organic pollutants can effectively degrade the pollutants under irradiation of visible light. A narrow band gap semiconductor can be used as a photocatalyst under irradiation of visible light, however, the fast recombination of photo-induced positive holes and electrons inhibits the photocatalytic activity (Li et al., 2019; Huang et al., 2017; Zhong et al., 2017 ). Therefore, attempts are made to inhibit the recombination of photo-induced positive holes and electrons by developing composite materials. In this respect, several studies have been reported for the synthesis of active visible-light photocatalysts for the treatment of wastewater contaminated with organic pollutants (Li et al., 2018; Gan et al., 2018). The development of visible light-responsive active photocatalyst for dyes contaminated wastewater is a hot topic among the researchers of photocatalysis (Wang et al., 2022; Li et al., 2021; Li et al., 2022a ).

The semiconductor bismuth oxide, Bi₂O₃, has recently attracted the interest of researchers due to its suitable price, stable structure, and suitable band gap energies. The bismuth oxide, Bi₂O₃, exists in different crystal types: the α-Bi₂O₃, β-Bi₂O₃, γ-Bi₂O₃, δ-Bi₂O_3, ε- Bi₂O₃ and ω-Bi₂O₃ (Zhang et al., 2018; Ho et al., 2013). Among different crystal types, α-Bi₂O₃, β-Bi₂O₃ have been widely used in catalysis, chemical sensors, fuel cells, photovoltaic cells, and optical thin films. The α-Bi₂O₃ and β-Bi₂O₃ have band gap of 2.85 and 2.58 eV respectively, hence both can be activated under visible irradiation (Chen et al., 2018b; Song et al., 2020). However, the fast recombination photoinduced electron-hole limits the practical application of Bi₂O₃ as a visible light photocatalyst. Therefore, attempts have been made to reduce the rate of recombination of photoinduced electron-hole. The coupling of Bi₂O₃ with semiconductors is one of the effective ways to separate the photoinduced electron and hole. The coupling of Bi₂O₃ with semiconductor metal oxides results in the formation of a heterojunction interface with an electric field between two semiconductors. In this way, the electric field created at the heterojunction assists the transport of charges from one semiconductor to another resulting in an effective separation between the photoinduced charges (Bhaviya Raj et al., 2021; Kaur et al., 2020; Ansari et al., 2021; Balachandran and Swaminathan, 2012 ). Hence in Bi₂O₃-semiconductor heterojunctions, advantages such as separation of charges increased lifetime of charges, and enhanced transfer efficiency of the charges to the adsorbed substrate can be achieved. In this study, the development of heterojunction formed by the coupling of Bi₂O₃ with spinel cobalt tetroxide (Co₃O₄) is reported. The spinel cobalt oxide (Co₃O₄) which is composed of Co (II) and Co (III) has been studied extensively due to its extraordinary properties. The high catalytic activity of Co₃O₄ is thought to be due to adsorption of oxygen in different states, oxygen defects, and variance in oxygen holes in Co₃O₄. Furthermore, the narrow band gap in the range of 1.2–2.1 eV makes Co₃O₄ attractive in photocatalysis for the treatment of wastewater contaminated with organic pollutants (Malefane, 2020; Hu et al., 2019; Luo et al., 2019; Zhao et al., 2019; Rao and Sunandana, 2008 ). As Bi₂O₃ has oxygen vacancies in its crystals, and Co₃O₄ is rich with oxygen content, therefore Bi₂O₃ promotes mobility and activity of lattice oxygen in Co₃O₄ which results in separation of photoinduced electron-hole pair and ultimately enhances the photocatalytic activity. Hence, we attempted to develop an environmentally friendly and cost-effective method for synthesis of Co₃O₄-Bi₂O₃ photocatalyst by one step co-precipitation method and evaluate the photocatalytic activity by degradation of rhodamine B dye.

2 Experimental

2.1

2.1 Synthesis of photocatalyst

The Co₃O₄-Bi₂O₃ hetero-structure was prepared by the coprecipitation method. Typically, 12.5 mmol of cobalt nitrate hexahydrate and 12.5 mmol of bismuth nitrate pentahydrate were dissolved in 10 mL (1 M) nitric acid solution under vigorous stirring. Then, 1 M of sodium hydroxide solution was added dropwise to the above-mixed solution under continuous stirring at 60 °C till pH 12 was obtained. The solution was further stirred for 2 h at 60 °C. As a result, a green precipitate was formed. The resultant precipitate was filtered, washed with ethanol, and distilled water till all unreacted ions were eliminated from the prepared precipitate. Then, the washed precipitate was dried at 100 °C overnight. Finally, the dried residue was calcined at 500 °C for 3 h which resulted in black colored Co₃O₄-Bi₂O₃ hetero-structure.

For comparison, Co₃O₄ and Bi₂O₃ were also prepared. The Co₃O₄ was prepared as follows. A 100 mL solution of cobalt nitrate hexahydrate (0.03 M) was mixed with a 100 mL solution of potassium carbonate (0.06 M) under sitting. The resultant reaction mixture was stirred for 7 h at 70 °C. the obtained residue was filtered, washed, and dried at 100 °C for 12 h. Finally, the dried sample was calcined at 500 °C for 3 h to get Co₃O₄ particles.

The Bi₂O₃ was prepared by adding 1 M sodium hydroxide solution to a solution containing 4.85 g bismuth nitrate pentahydrate in 100 mL till pH 12 was obtained. Concentrated nitric acid was used for the dissolution of bismuth nitrate. The resultant precipitate was filtered, washed, and dried at 100 °C for 12 h. The dried product was calcined at 500 °C to get light yellow Bi₂O₃ particles

2.2

2.2 Characterization

X-rays diffraction, energy dispersive spectroscopy, scanning electron microscopy, thermal gravimetric analysis, and infrared spectroscopy was used for characterization of prepared material using JOEL-JDX-3532 Japan X-ray diffractometer, JEOL-JSM 5910 Japan Scanning electron microscope, JSM5910 UK Energy dispersive X-rays spectrophotometer, Perkin Elmer 6300 TGA analyzer, and Bruker VRTEX70 Infrared spectrophotometer, respectively.

2.3

2.3 Catalytic activity

The photocatalytic activities of synthesized particles were determined with photodegradation of rhodamine B dye. Typically, a solution of rhodamine B dye was charged with a predetermined catalyst dose and stirred under sunlight irradiation for 120 min. Progress of photocatalytic degradation was monitored by sampling and analyzing the reaction mixture at a regular time interval. Blank experiments were performed by stirring the dye solution and dye solution with catalyst under irradiation and dark conditions, respectively. UV/Vis spectrophotometer (U-2800, HITACHI, Japan) was used for the measurement of photocatalytic activity.

3 Results and discussion

3.1

3.1 Characterization

The formation of Co₃O₄, Bi₂O_3, and Co₃O₄-Bi₂O₃ was confirmed by XRD analysis. The XRD of Co₃O₄ given in Fig. 1 consists of sharp diffraction peaks which show the crystalline nature of Co₃O₄. The diffraction peaks observed at 2θ ∼ 18, 30, 37, 43, and 58° have been indexed to the spinel structure of Co₃O₄ (Manickam et al., 2016; Rao and Sunandana, 2008; Manigandan et al., 2013 ). Similarly, the diffraction peaks at 2θ ∼ 12, 26, 33, 36, 41, 46, 54, and 58 are observed in the XRD of Bi₂O₃. All these diffraction peaks correspond to β-Bi₂O₃. The remaining weak diffraction peaks represent the γ-Bi₂O₃ (Z. Li et al., 2020; Iyyapushpam et al., 2015; Liang et al., 2014; Huang et al., 2016 ). The existence of characteristic peaks of Co₃O₄ and Bi₂O₃ in the XRD pattern of Co₃O₄-Bi₂O₃ suggest the successful formation of Co₃O₄-Bi₂O₃ heterojunction (Z. Li et al., 2020).

X-ray diffraction analyses Co3O4, Bi2O3, and Co3O4-Bi2O3.

The elemental composition of Co₃O₄, Bi₂O₃, and Co₃O₄-Bi₂O₃ was investigated by energy dispersive spectroscopy using JSM5910, INCA200 UK. Fig. 2 shows the energy-dispersive spectra of the samples. The energy dispersive spectrum of Co₃O₄ given in Fig. 2a shows peaks for Co and O only which confirms the purity of the sample. The EDS analysis showed that prepared cobalt oxide is composed of 87.3 wt% Co and 12.68 wt% O. The energy dispersive spectrum of bismuth oxide (Fig. 2b) shows peaks for Bi, O, and C. The EDS analysis showed that prepared bismuth oxide is composed of 58.08, 9.97, and 4.95% Bi, O, and C respectively. The existence of C may be due to impurities in precursor material. Similarly, the energy dispersive spectrum of cobalt oxide-bismuth oxide composite (Fig. 2c) shows that the composite is composed of 11.6, 70.83, 13.92, and 4.19% Co, Bi, O, and C respectively.

EDS analysis of Co3O4 (a), Bi2O3 (b), and Co3O4-Bi2O3 (c).

The morphology of Co₃O₄, Bi₂O_3, and Bi₂O₃-Co₃O₄ was studied by scanning electron microscopy with JEOL-JSM-5910, Japan scanning electron microscope. JEOL-JSM-420, Japan coating machine was used for mounting and coating the samples with gold foil. The scanning electron micrographs given in Fig. 3a-c show that the particles of as-prepared samples are irregular in shape, non-agglomerated, and dispersed. The non-agglomerated and dispersed particles have enhanced catalytic activity as the active centers are easily accessible to substrate molecules. Fig. 3d and Fig. 3e show the TEM and HR-TEM of Bi₂O₃-Co₃O₄ respectively. Fig. 3d shows that Bi₂O₃-Co₃O_{4 is} composed of particles with sizes less than 50 nm. The well-defined lattice fringes indicated in HR-TEM show that as prepared Bi₂O₃-Co₃O₄ is highly crystallized (Ding et al., 2012).

SEM of Co3O4 (a), Bi2O3 (b) and Co3O4-Bi2O3 (c) TEM (d) and HR-TEM (e) images of Co3O4-Bi2O3.

Thermal stability of as-prepared samples was estimated by thermal gravimetric analysis using Perkin Elmer 6300 TGA analyzer. As given in Fig. 4, there was only about a 5% loss in weight of the samples up to 700 °C, which is attributed to loss of moisture content. The non-significant weight loss shows the stability of as-prepared samples over a wide range of temperatures.

TGA analysis of Co3O4 (a), Bi2O3 (b), and Co3O4-Bi2O3 (c).

The typical bonds and functional groups of as-prepared samples were estimated by Fourier transform infrared spectroscopy (FTIR) using Bruker (VRTEX70 series). Fig. 5 shows the FTIR spectra of as-prepared samples in which several peaks can be observed. The absorption peak at 1634 cm⁻¹ is attributed to –OH groups present at the surface of Co₃O₄-Bi₂O₃ heterojunction. The absorption bands at ∼445 cm⁻¹ and 846 cm⁻¹ have been assigned to stretching vibrations of Bi-O and Bi-O-Bi bonds, respectively. The absorption bands at ∼571 and 668 are representative peaks of Co₃O₄ due to Co-O stretching vibrations (Hammad et al., 2016; Ilyas, M, 2010; Li et al., 2017a; Saeed et al., 2012; Tang et al., 2018 ). The FTIR result shows the successful formation of Co₃O₄-Bi₂O₃ heterojunction.

FTIR analysis of Co3O4 (a), Bi2O3 (b), and Co3O4-Bi2O3 (c).

3.2

3.2 Catalytic activity

The photocatalytic activity of Co₃O₄, Bi₂O_3, and Co₃O₄-Bi₂O₃ was evaluated by performing photodegradation experiments of rhodamine B dye in the presence of 0.05 g of aforementioned catalysts under visible irradiation. A 50 mL rhodamine B (100 mg/L) was taken in a Pyrex glass beaker and was stirred under irradiation for 30 min. Then, as a blank reaction, 0.05 g Co₃O₄/Bi₂O₃/Co₃O₄-Bi₂O₃ was added to the dye solution and stirred for 30 min under dark to clarify the effect of adsorption. For evaluation of catalytic performance, the reaction mixture was then irradiated under stirring. The change in concentration of rhodamine B due to catalytic degradation was monitored by measurement of absorbance at wavelength 554 nm using a UV–visible spectrophotometer. Fig. 6a shows the visible spectra of the reaction samples taken from the solution of rhodamine B dye treated with Co₃O₄-Bi₂O₃. As the normalized temporal changes in absorbance (A_t/A_o) of rhodamine B during the photocatalytic process are proportional to normalized concentrations (C_t/C_o) of rhodamine B dye, therefore, the photocatalytic activity was expressed as A_t/A_o vs t as given in Fig. 6b (A_t: absorbance of rhodamine B at time t, A_o; Initial absorbance of rhodamine B, C_t: concentration of rhodamine B at time t, C_o: initial concentration of rhodamine B). It was observed that Co₃O₄-Bi₂O₃ showed the best catalytic performance with ∼92% degradation of rhodamine B dye than Co₃O₄ and Bi₂O₃ with 14 and 34% removal of rhodamine B dye, respectively. The obtained results show that coupling of Co₃O₄ with Bi₂O₃ significantly promotes catalytic activity.

a) Visible absorption spectra of reaction mixture treated with Co3O4-Bi2O3 b) Comparison of photocatalytic activity of Co3O4, Bi2O3, and Co3O4-Bi2O3 towards photodegradation of rhodamine B dye.

A leaching experiment was also performed to confirm whether the photodegradation of rhodamine B is a heterogeneous or homogeneous reaction. For this purpose, 0.1 g Co₃O₄-Bi₂O₃ was suspended in 50 mL distilled water and stirred under irradiation for 120 min. Then, the Co₃O₄-Bi₂O₃ was filtered and a known solution of rhodamine B was added to the filtrate to get a ∼100 mg/L dye solution and analyzed with a UV–visible spectrophotometer. Finally, the dye solution was again treated with irradiation and analyzed with a UV–visible spectrophotometer after 120 min. The analysis showed that there was no change in the concentration of the dye. Hence, it is concluded that Co₃O₄-Bi₂O₃ does not leach to an aqueous medium in this study.

The stability and recycling ability of Co₃O₄-Bi₂O₃ as photocatalyst was also confirmed. For this purpose, the spent photocatalyst was washed with ethanol and DD water followed by drying. Then, the dried Co₃O₄-Bi₂O₃ was re-employed for photodegradation of rhodamine B dye under pre-determined experimental conditions. In the same way, the Co₃O₄-Bi₂O₃ was recycled for three-time. The results showed that there was no significant loss in photocatalytic activity of Co₃O₄-Bi₂O₃ towards the photodegradation of rhodamine B dye. Hence, it is concluded that the prepared Co₃O₄-Bi₂O₃ is stable under present experimental conditions and can be recycled again.

Co₃O₄-Bi₂O₃ is a second-generation photocatalyst. The second-generation photocatalysts, also called as heterojunctions were developed to overcome the drawback of first-generation photocatalysts (Li et al., 2022b; Liu et al., 2022; Saeed et al., 2022; Anwer et al., 2019 ). The single-component metal oxides are classified as first-generation photocatalysts. The fast recombination of electron-hole is a basic drawback of first-generation photocatalysts. In second-generation photocatalysts, the photoinduced electrons are confined in the conduction band of one component of heterojunction while the holes are confined in the valence band of the other component. This spatial separation of the photoinduced electrons and holes inhibits their recombination. As a result, active sites are generated at which degradation of organic pollutants takes place. The second-generation photocatalytic materials show light absorbance in the visible region (λ ≥ 420 nm) accompanied with lower band gap energies than first-generation photocatalytic materials. The Mott-Schottky measurement has been reported for band-edge position and conductivity types of Bi₂O₃ and Co₃O₄ having band potentials of 0.28 and 0.5 V vs. Ag/AgCl, respectively. The E_CB of Bi₂O₃ and E_VB of Co₃O₄ has been estimated as 0.28 and 0.90 V vs NHE, respectively. Accordingly, the E_VB of Bi₂O₃ and E_CB of Co₃O₄ has been estimated as 2.73 and −1.47 V, respectively (Ma et al., 2022; X. Liu et al., 2021; Xu et al., 2018; Zhu et al., 2018 ). Hence, the energy band diagram for Co₃O₄-Bi₂O₃ is constructed as given in Fig. 7. The VB of Co₃O₄ can accept the photoexcited electrons from the CB of Bi₂O₃ due to the short distance between the bands. This transfer of electrons offers a Z-scheme charge transfer model in Co₃O₄-Bi₂O₃ heterojunction. Hence, the photodegradation of rhodamine B dye over Co₃O₄-Bi₂O₃ photocatalyst can be described by a direct Z-scheme charge transfer mechanism. According to this mechanism, the photoexcited electrons in CB of Bi₂O₃ flow to the VB of Co₃O₄ under visible light irradiation. The flow of electrons from CB of Bi₂O₃ to the VB of Co₃O₄ reduces the recombination of positive holes and electrons and ultimately it results in enhancement of the photocatalytic activity towards photodegradation of rhodamine B dye (S. Li et al., 2020a; C. Liu et al., 2021; Wang et al., 2020; Zhang et al., 2020 ).

Schematic diagram of Z-scheme mechanism.

Hence, the photodegradation of rhodamine B dye in the present study can be described as follow.

(1)

{Co}_{3} O_{4} - {Bi}_{2} O_{3} + V i s i b l e i r r a d i a t i o n \to h^{+} ({Co}_{3} O_{4} - {Bi}_{2} O_{3}) + e^{-} ({Co}_{3} O_{4} - {Bi}_{2} O_{3})

(2)

h^{+} ({Co}_{3} O_{4} - {Bi}_{2} O_{3}) + H_{2} O \to O H

(3)

e^{-} ({Co}_{3} O_{4} - {Bi}_{2} O_{3}) + {(O_{2})}_{ads} \to \to O H

(4)

[R H] + O H \to D e g r a d a t i o n p r o d u c t s

The photoinduced electron, positive hole, and OH radicals are the active species that contribute to the photodegradation of rhodamine B dye. The role played by these species was confirmed by scavenging experiments. For this purpose, EDTA and BQ were separately used as scavengers each of which significantly suppressed the photodegradation activity. Since the EDTA arrests the positive holes, therefore the activity decreased in the presence of EDTA. Similarly, the addition of BQ suppresses photodegradation because it reacts with superoxide anion radicals (Song et al., 2020; Xu et al., 2019).

Based on the above mechanism, the rate expression is written as

(5)

- \frac{d [R H]}{dt} = k {(O_{2})}_{ads} {[R H]}^{n}

(6)

- \frac{d [R H]}{dt} = k_{obs} {[R H]}^{n}

(7)

\ln \frac{A_{o}}{A_{t}} = k_{1} t (F o r n = 1)

(8)

\frac{1}{A_{t}} = \frac{1}{A_{o}} + k_{2} t (F o r n = 2)

k_obs, k₁, k₂, A_o, and A_t is observed rate constant, 1st order rate constant, 2nd order rate constant, initial absorbance of rhodamine B, and absorbance at time t respectively.

Fig. 8 shows the kinetics treatment of the photodegradation degradation data of rhodamine B. The 1st order rate constant (k₁) and 2nd order rate constant (k₂) are given in Table 1. As the regression coefficient (R²) values are higher for 1st order kinetics treatment, therefore, it is proposed that the degradation of rhodamine B dye in this study follows 1st order reaction kinetics. The rate constant for Co₃O₄-Bi₂O₃ catalyzed photodegradation of rhodamine B was 6 times and 3 times higher than the rate constant for Co₃O₄ catalyzed and Bi₂O₃ catalyzed photodegradation of rhodamine B respectively. Hence, the formation of Co₃O₄-Bi₂O₃ heterostructure significantly boosts the catalytic performance of Co₃O₄ and Bi₂O₃.

Kinetics treatment of experimental data with Co3O4 (a), Bi2O3 (b), and Co3O4-Bi2O3 (c).

Table 1 The 1st order and 2nd order rate constants for photodegradation of rhodamine B.

Catalyst	$\ln \frac{A_{o}}{A_{t}} = k_{1} t$		$\frac{1}{A_{t}} = \frac{1}{A_{o}} + k_{2} t$		*Catalytic efficiency (%)
Catalyst	k₁	R²	k₂	R²	*Catalytic efficiency (%)
Co₃O₄	0.0015	0.994	0.006	0.975	14
Bi₂O₃	0.003	0.977	0.0137	0.951	34
Co₃O₄-Bi₂O₃	0.0089	0.988	0.0541	0.879	92

*Reaction duration: 120 min.

3.3

3.3 Effect of pH

The pH of the solution significantly affects the catalytic activity; therefore, the pH was optimized as well in this study. The effect of pH on the catalytic activity of Co₃O₄-Bi₂O₃ was evaluated by performing a degradation experiment at pH 4, 6, 8, and 10. Fig. 9 shows the effect of pH on photocatalytic degradation of rhodamine B dye (the numbers given in bar graphs represent the catalytic efficiency). Every experimental cycle was performed with a 0.05 g Co₃O₄-Bi₂O₃ per 50 mL solution (100 mg/L). The reaction duration was 60 min. It was observed that an increase in pH up to 8 favored the catalytic activity. The point of zero charges (PZC) for Co₃O₄-Bi₂O₃ has been reported as pH 8.4 (Ivanova-Kolcheva et al., 2020), hence the surface of Co₃O₄-Bi₂O₃ becomes negative at pH higher than PZC and positive at pH lower than PZC. At pH lower than PZC, both the rhodamine B and surface of the Co₃O₄-Bi₂O₃ are positive, therefore the catalytic activity is low at low pH due to electrostatic repulsion. Similarly, the negative surface of Co₃O₄-Bi₂O₃ at higher pH also opposes the adsorption of rhodamine B, hence the maximum catalytic activity exhibited at pH 8.

Effect of pH on the catalytic activity of Co3O4-Bi2O3 towards photodegradation of rhodamine B.

3.4

3.4 Effect of catalyst dose

The dependence of the photocatalytic activity of Co₃O₄-Bi₂O₃ towards photodegradation of rhodamine B on photocatalyst dosage has been investigated by performing photodegradation experiments with different dosages of Co₃O₄-Bi₂O₃ under identical conditions. In a model experiment, a 50 mL solution of rhodamine B dye (100 mg/L) was treated with a known amount of Co₃O₄-Bi₂O₃ for 60 min. Fig. 10 shows the dependence of catalytic activity on catalyst dosage. It was observed that an increase in catalyst dose from 0.01 to 0.05 g increased the degradation from 18 to 36%, however, further increase in catalyst dose caused a decrease in degradation efficiency. The enhancement in catalytic efficiency with an increase in catalyst dose is due to two reasons: (1) The number of molecules of rhodamine B adsorbed increases with catalyst dosage, (2) the density of Co₃O₄-Bi₂O₃ particles under illumination increases with catalyst dosage. The decrease in catalytic efficiency at higher catalyst dosage is due to the scattering of light. Hence, a catalyst dose of 0.05 g/50 mL of dye solution is found to be the optimum catalyst dosage in this study.

Effect of catalyst dose on the catalytic activity of Co3O4-Bi2O3 towards photodegradation of rhodamine B.

3.5

3.5 Effect of concentration

The initial concentration of dye also affects the catalytic activity, therefore the concentration dependence of catalytic activity has been also investigated. This investigation was carried out by performing separate photodegradation experiments of rhodamine B dye in the presence of 0.05 g Co₃O₄-Bi₂O₃ using 100, 200, and 300 mg/L solutions of rhodamine B dye. Fig. 11a shows the effect of concentration on catalytic activity Co₃O₄-Bi₂O₃ towards photodegradation of rhodamine B dye. It was found that catalytic activity decreased with an increase in the initial concentration of rhodamine B dye. The decrease in catalytic activity with an increase in the concentration of dye is due to three reasons (Adeel et al., 2021; Balcha et al., 2016; Nisar et al., 2022; Saeed et al., 2018 ):

The pathlength of a photon decreases with an increase in the concentration of dye
The rhodamine B dye absorbs photons significantly than catalyst at a higher concentration of dye
The ratio of OH radicals to rhodamine B molecules decreases with an increase in concentration

Effect of concentration of dye on the catalytic activity of Co3O4-Bi2O3 towards photodegradation of rhodamine B.

The degradation data given in Fig. 11a was analyzed for kinetics studies using kinetics equation (7). Fig. 11b shows the fitting of the 1st order kinetics model (equation (7)) to experimental data. The kinetics parameters given in Table 2 shows that the rate constant decreases with an increase in the initial concentration of rhodamine B dye.

Table 2 Kinetics parameters for Co₃O₄-Bi₂O₃ catalyzed photodegradation of rhodamine B.

Parameter	100 mg/L	200 mg/L	300 mg/L
k₁ (min⁻¹)	0.0089	0.0056	0.0039
R²	0.988	0.969	0.948
*Catalytic efficiency (%)	92	72	50

*Reaction duration: 120 min.

4 Conclusions

Herein, we prepared the Co₃O₄-Bi₂O₃ heterojunction as visible-light responsive photocatalyst by coprecipitation method for photodegradation of rhodamine B dye successfully. The Co₃O₄-Bi₂O₃ heterojunction was characterized by XRD, EDS, SEM, TGA, and FTIR. The as-prepared Co₃O₄-Bi₂O₃ heterojunction was utilized as a photocatalyst for photodegradation of rhodamine B dye using a 100 mg/L solution. The photocatalytic activity of Co₃O₄-Bi₂O₃, Co₃O_4, and Bi₂O₃ towards photodegradation of rhodamine B dye was found as 92, 14, and 34%, respectively. The 1st order and 2nd order kinetics models were applied to the data of photocatalytic degradation of rhodamine b dye. The effect of pH, catalyst dose, and initial concentration of rhodamine B dye on photocatalytic performance was investigated. The Co₃O₄-Bi₂O₃ heterojunction was found as an efficient visible-light-driven photocatalyst for photodegradation of rhodamine B dye.

Acknowledgements

The authors express their gratitude to Princess Nourah bint Abdulrahman University Researchers Supporting Project (Grant No. PNURSP2022R11), Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia. The authors extend their appreciation to the Deanship of Scientific Research at King Khalid University, Saudi Arabia for funding this work through the Research Groups Program under grant number G.R.P.: 349/43.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

References

Adeel M., Saeed M., Khan I., Muneer M., Akram N., . Synthesis and Characterization of Co-ZnO and Evaluation of Its Photocatalytic Activity for Photodegradation of Methyl Orange. ACS Omega. 2021;6:1426-1435.
[CrossRef] [Google Scholar]
Ansari S., Ansari M.S., Satsangee S.P., Jain R., . Bi₂O₃/ZnO nanocomposite: Synthesis, characterizations and its application in electrochemical detection of balofloxacin as an anti-biotic drug. J. Pharm. Anal.. 2021;11:57-67.
[CrossRef] [Google Scholar]
Anwer H., Mahmood A., Lee J., Kim K.H., Park J.W., Yip A.C.K., . Photocatalysts for degradation of dyes in industrial effluents: Opportunities and challenges. Nano Res.. 2019;12:955-972.
[CrossRef] [Google Scholar]
Balachandran S., Swaminathan M., . Facile fabrication of heterostructured Bi₂O₃-ZnO photocatalyst and its enhanced photocatalytic activity. J. Phys. Chem. C. 2012;116:26306-26312.
[CrossRef] [Google Scholar]
Balcha A., Yadav O.P., Dey T., . Photocatalytic degradation of methylene blue dye by zinc oxide nanoparticles obtained from precipitation and sol-gel methods. Environ. Sci. Pollut. Res.. 2016;23:25485-25493.
[CrossRef] [Google Scholar]
Bhaviya Raj R., Umadevi M., Parimaladevi R., . Synergy photodegradation of basic dyes by zno/bi2o3 nanocomposites under visible light irradiation. Iran. J. Chem. Chem. Eng.. 2021;40:1121-1131.
[Google Scholar]
Chen M., Chu W., Beiyuan J., Huang Y., . Enhancement of UV-assisted TiO₂ degradation of ibuprofen using Fenton hybrid process at circumneutral pH. Chin. J. Catal.. 2018;39:701-709.
[CrossRef] [Google Scholar]
Chen M., Yao J., Huang Y., Gong H., Chu W., . Enhanced photocatalytic degradation of ciprofloxacin over Bi₂O₃/(BiO)₂CO₃ heterojunctions: efficiency, kinetics, pathways, mechanisms and toxicity evaluation. Chem. Eng. J.. 2018;334:453-461.
[CrossRef] [Google Scholar]
Ding Y., Zhu L., Huang A., Zhao X., Zhang X., Tang H., . A heterogeneous Co₃O₄-Bi₂O₃ composite catalyst for oxidative degradation of organic pollutants in the presence of peroxymonosulfate. Catal. Sci. Technol.. 2012;2:1977-1984.
[CrossRef] [Google Scholar]
Gan L., Xu L.J., Qian K., Wang Y.D., Jiang F.Y., . Hydrothermal synthesis of magnetic graphene-BiFeO₃ hybrids and their photocatalytic properties. Xinxing Tan Cailiao/New Carbon Materials. 2018;33:221-228.
[Google Scholar]
Hammad A.H., Marzouk M.A., ElBatal H.A., . The Effects of Bi₂O₃ on Optical, FTIR and Thermal Properties of SrO-B₂O₃ Glasses. Silicon. 2016;8:123-131.
[CrossRef] [Google Scholar]
Ho C.-H., Chan C.-H., Huang Y.-S., Tien L.-C., Chao L.-C., . The study of optical band edge property of bismuth oxide nanowires α-Bi₂O₃. Opt. Express. 2013;21:11965.
[CrossRef] [Google Scholar]
Hu L., Zhang G., Liu M., Wang Q., Dong S., Wang P., . Application of nickel foam-supported Co₃O₄-Bi₂O₃ as a heterogeneous catalyst for BPA removal by peroxymonosulfate activation. Sci. Total Environ.. 2019;647:352-361.
[CrossRef] [Google Scholar]
Huang X., Zhang W., Tan Y., Wu J., Gao Y., Tang B., . Facile synthesis of rod-like Bi₂O₃ nanoparticles as an electrode material for pseudocapacitors. Ceram. Int.. 2016;42:2099-2105.
[CrossRef] [Google Scholar]
Huang Y., Liang Y., Rao Y., Zhu D., Cao J.J., Shen Z., Ho W., Lee S.C., . Environment-Friendly Carbon Quantum Dots/ZnFe₂O₄ Photocatalysts: Characterization, Biocompatibility, and Mechanisms for NO Removal. Environ. Sci. Technol.. 2017;51:2924-2933.
[CrossRef] [Google Scholar]
Ilyas, M Saeed M, . Oxidation of benzyl alcohol in liquid phase catalyzed by cobalt oxide. Int. J. Chem. Reactor Eng.. 2010;8:A77.
[CrossRef] [Google Scholar]
Ivanova-Kolcheva V., Sygellou L., Stoyanova M., . Enhanced catalytic degradation of acid orange 7 dye by peroxymonosulfate on Co₃O₄ promoted by Bi₂O₃. Acta Chim. Slov.. 2020;67:609-621.
[Google Scholar]
Iyyapushpam S., Nishanthi S.T., Padiyan D.P., . Synthesis of β-Bi₂O₃ towards the application of photocatalytic degradation of methyl orange and its instability. J. Phys. Chem. Solids. 2015;81:74-78.
[CrossRef] [Google Scholar]
Kaur G., Sharma S., Bansal P., . Visible light responsive heterostructured α-Bi₂O₃/ZnO doped β-Bi₂O₃ photocatalyst for remediation of organic pollutants. Desalin. Water Treat.. 2020;201:349-355.
[CrossRef] [Google Scholar]
Li R., Zhou D., Luo J., Xu W., Li J., Li S., Cheng P., Yuan D., . The urchin-like sphere arrays Co₃O₄ as a bifunctional catalyst for hydrogen evolution reaction and oxygen evolution reaction. J. Power Sources. 2017;341:250-256.
[CrossRef] [Google Scholar]
Li S., Chen J., Hu S., Wang H., Jiang W., Chen X., . Facile construction of novel Bi₂WO₆/Ta₃N₅ Z-scheme heterojunction nanofibers for efficient degradation of harmful pharmaceutical pollutants. Chem. Eng. J.. 2020;402
[CrossRef] [Google Scholar]
Li S., Hu S., Jiang W., Liu Y., Zhou Y., Liu J., Wang Z., . Facile synthesis of cerium oxide nanoparticles decorated flower-like bismuth molybdate for enhanced photocatalytic activity toward organic pollutant degradation. J. Colloid Interface Sci.. 2018;530:171-178.
[CrossRef] [Google Scholar]
Li S., Hu S., Jiang W., Zhang J., Xu K., Wang Z., . In situ construction of WO₃ nanoparticles decorated Bi₂MoO₆ microspheres for boosting photocatalytic degradation of refractory pollutants. J. Colloid Interface Sci.. 2019;556:335-344.
[CrossRef] [Google Scholar]
Li S., Shen X., Liu J., Zhang L., . Synthesis of Ta₃N₅/Bi₂MoO₆ core-shell fiber-shaped heterojunctions as efficient and easily recyclable photocatalysts. Environ. Sci. Nano. 2017;4:1155-1167.
[CrossRef] [Google Scholar]
Li S., Wang C., Cai M., Yang F., Liu Y., Chen J., Zhang P., Li X., Chen X., . Facile fabrication of TaON/Bi2MoO6 core–shell S-scheme heterojunction nanofibers for boosting visible-light catalytic levofloxacin degradation and Cr(VI) reduction. Chem. Eng. J.. 2022;428
[CrossRef] [Google Scholar]
Li S., Wang C., Liu Y., Cai M., Wang Y., Zhang H., Guo Y., Zhao W., Wang Z., Chen X., . Photocatalytic degradation of tetracycline antibiotic by a novel Bi₂Sn₂O₇/Bi₂MoO₆ S-scheme heterojunction: performance, mechanism insight and toxicity assessment. Chem. Eng. J.. 2022;429
[CrossRef] [Google Scholar]
Li S., Wang C., Liu Y., Xue B., Chen J., Wang H., Liu Y.u., . Facile preparation of a novel Bi₂Wo₆/calcined mussel shell composite photocatalyst with enhanced photocatalytic performance. Catalysts. 2020;10:1-11.
[CrossRef] [Google Scholar]
Li S., Wang C., Liu Y., Xue B., Jiang W., Liu Y.u., Mo L., Chen X., . Photocatalytic degradation of antibiotics using a novel Ag/Ag₂S/Bi₂MoO₆ plasmonic p-n heterojunction photocatalyst: mineralization activity, degradation pathways and boosted charge separation mechanism. Chem. Eng. J.. 2021;415
[CrossRef] [Google Scholar]
Li Z., Tang X., Huang G., Luo X., He D., Peng Q., Huang J., Ao M., Liu K., . Bismuth MOFs based hierarchical Co₃O4-Bi₂O₃ composite: an efficient heterogeneous peroxymonosulfate activator for azo dyes degradation. Sep. Purif. Technol.. 2020;242
[CrossRef] [Google Scholar]
Liang J., Zhu G., Liu P., Luo X., Tan C., Jin L., Zhou J., . Synthesis and characterization of Fe-doped β-Bi₂O₃ porous microspheres with enhanced visible light photocatalytic activity. Superlattices Microstruct.. 2014;72:272-282.
[CrossRef] [Google Scholar]
Liu C., Mao S., Shi M., Wang F., Xia M., Chen Q., Ju X., . Peroxymonosulfate activation through 2D/2D Z-scheme CoAl-LDH/BiOBr photocatalyst under visible light for ciprofloxacin degradation. J. Hazard. Mater.. 2021;420
[CrossRef] [Google Scholar]
Liu C., Mao S., Wang H., Wu Y., Wang F., Xia M., Chen Q., . Peroxymonosulfate-assisted for facilitating photocatalytic degradation performance of 2D/2D WO₃/BiOBr S-scheme heterojunction. Chem. Eng. J.. 2022;430
[CrossRef] [Google Scholar]
Liu X., Yang Z., Zhang L., . In-situ fabrication of 3D hierarchical flower-like β-Bi₂O₃@CoO Z-scheme heterojunction for visible-driven simultaneous degradation of multi-pollutants. J. Hazard. Mater.. 2021;403
[CrossRef] [Google Scholar]
Lo Piccolo E., Landi M., . Red-leafed species for urban “greening” in the age of global climate change. J. For. Res.. 2021;32:151-159.
[CrossRef] [Google Scholar]
Luo S., Wang R., Yin J., Jiao T., Chen K., Zou G., Zhang L., Zhou J., Zhang L., Peng Q., . Preparation and dye degradation performances of self-assembled MXene-Co₃O₄ nanocomposites synthesized via solvothermal approach. ACS Omega. 2019;4:3946-3953.
[CrossRef] [Google Scholar]
Ma H., Yang X., Tang X., Cao X., Dai R., . Self-assembled Co-doped β-Bi₂O₃ flower-like structure for enhanced photocatalytic antibacterial effect under visible light. Appl. Surf. Sci.. 2022;572
[CrossRef] [Google Scholar]
Malefane M.E., . Co₃O₄/Bi₄O₅I₂/Bi₅O₇I C-Scheme Heterojunction for Degradation of Organic Pollutants by Light-Emitting Diode Irradiation. ACS Omega 2020
[CrossRef] [Google Scholar]
Manickam M., Ponnuswamy V., Sankar C., Suresh R., Mariappan R., Chandrasekaran J., . The Effect of Solution pH on the Properties of Cobalt Oxide Thin Films Prepared by Nebulizer Spray Pyrolysis Technique. Int. J. Thin Films Sci. Technol.. 2016;5:155-161.
[Google Scholar]
Meng L., Sun Y., Gong H., Wang P., Qiao W.C., Gan L., Xu L.J., . Research progress of the application of graphene-based materials in the treatment of water pollutants. Xinxing Tan Cailiao/New Carbon Materials. 2019;34:220-237.
[CrossRef] [Google Scholar]
Manigandan R., Giribabu K., Suresh R., Vijayalakshmi L., Stephen A., Narayanan V., . Cobalt Oxide Nanoparticles: Characterization and its Electrocatalytic Activity towards Nitrobenzene. Chem. Sci. Trans.. 2013;2
[CrossRef] [Google Scholar]
Nisar A., Saeed M., Muneer M., Usman M., Khan I., . Synthesis and characterization of ZnO decorated reduced graphene oxide (ZnO-rGO) and evaluation of its photocatalytic activity toward photodegradation of methylene blue. Environ. Sci. Pollut. Res.. 2022;29:418-430.
[CrossRef] [Google Scholar]
Rao K.V., Sunandana C.S., . Synthesis and characterization of Co3O₄ nanoparticles. AIP Conf. Proc.. 2008;1003:97-99.
[CrossRef] [Google Scholar]
Saeed M., Ilyas M., Siddique M., . Oxidative degradation of phenol in aqueous medium catalyzed by lab prepared cobalt oxide. J. Chem. Soc. Pak.. 2012;34:626-633.
[Google Scholar]
Saeed, M., Ahmad, A., Boddula, R., Inamuddin, Haq, A. ul, Azhar, A., 2018. Ag@Mn_xO_y: an effective catalyst for photo-degradation of rhodamine B dye. Environ. Chem. Lett. 16, 287-294. doi: 10.1007/s10311-017-0661-z.
Saeed, M., Muneer, M., Haq, A. ul, Akram, N., 2022. Photocatalysis: an effective tool for photodegradation of dyes—a review. Environmental Science and Pollution Research 29, 293–311. https://doi.org/10.1007/s11356-021-16389-7
Song C., Wang L.J., Sun S.M., Wu Y., Xu L.J., Gan L., . Preparation of visible-light photocatalysts of Bi2O₃/Bi embedded in porous carbon from Bi-based metal organic frameworks for highly efficient Rhodamine B removal from water. Xinxing Tan Cailiao/New Carbon Materials. 2020;35:609-618.
[CrossRef] [Google Scholar]
Tang X., Feng Q., Huang J., Liu K., Luo X., Peng Q., . Carbon-coated cobalt oxide porous spheres with improved kinetics and good structural stability for long-life lithium-ion batteries. J. Colloid Interface Sci.. 2018;510:368-375.
[CrossRef] [Google Scholar]
Wang C., Cai M., Liu Y., Yang F., Zhang H., Liu J., Li S., . Facile construction of novel organic–inorganic tetra (4-carboxyphenyl) porphyrin/Bi₂MoO₆ heterojunction for tetracycline degradation: performance, degradation pathways, intermediate toxicity analysis and mechanism insight. J. Colloid Interface Sci.. 2022;605:727-740.
[CrossRef] [Google Scholar]
Wang Z., Wang H., Zeng Z., Zeng G., Xu P., Xiao R., Huang D., Chen X., He L., Zhou C., Yang Y., Wang Z., Wang W., Xiong W., . Metal-organic frameworks derived Bi₂O₂CO₃/porous carbon nitride: A nanosized Z-scheme systems with enhanced photocatalytic activity. Appl. Catal. B. 2020;267
[CrossRef] [Google Scholar]
Xu L., Meng L., Zhang X., Mei X., Guo X., Li W., Wang P., Gan L., . Promoting Fe³⁺/Fe²⁺ cycling under visible light by synergistic interactions between P25 and small amount of Fenton reagents. J. Hazard. Mater.. 2019;379
[CrossRef] [Google Scholar]
Xu Q., Zhang L., Yu J., Wageh S., Al-Ghamdi A.A., Jaroniec M., . Direct Z-scheme photocatalysts: Principles, synthesis, and applications. Mater. Today. 2018;21:1042-1063.
[CrossRef] [Google Scholar]
Zhang L., Ghimire P., Phuriragpitikhon J., Jiang B., Gonçalves A.A.S., Jaroniec M., . Facile formation of metallic bismuth/bismuth oxide heterojunction on porous carbon with enhanced photocatalytic activity. J. Colloid Interface Sci.. 2018;513:82-91.
[CrossRef] [Google Scholar]
Zhang W., Mohamed A.R., Ong W.J., . Z-Scheme Photocatalytic Systems for Carbon Dioxide Reduction: Where Are We Now? Angewandte Chemie - International Edition. 2020;59:22894-22915.
[CrossRef] [Google Scholar]
Zhao Z., Fan J., Deng X., Liu J., . One-step synthesis of phosphorus-doped g-C₃N₄/Co₃O₄ quantum dots from vitamin B₁₂ with enhanced visible-light photocatalytic activity for metronidazole degradation. Chem. Eng. J.. 2019;360:1517-1529.
[CrossRef] [Google Scholar]
Zhong Y.K., Zhou B., Zhang C.J., Wu D., . Effects of surface oxygen functional groups on activated carbon on the adsorption and photocatalytic degradation activities of a TiO₂-AC hybrid for methylene blue and methylene orange. Xinxing Tan Cailiao/New Carbon Materials. 2017;32:460-466.
[CrossRef] [Google Scholar]
Zhu M., Sun Z., Fujitsuka M., Majima T., . Z-Scheme Photocatalytic Water Splitting on a 2D Heterostructure of Black Phosphorus/Bismuth Vanadate Using Visible Light. Angewandte Chemie - International Edition. 2018;57:2160-2164.
[CrossRef] [Google Scholar]

Introduction

Experimental

Synthesis of photocatalyst
Characterization
Catalytic activity

Results and discussion

Characterization
Catalytic activity
Effect of pH
Effect of catalyst dose
Effect of concentration

Conclusions

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[1] Adeel M., Saeed M., Khan I., Muneer M., Akram N., . Synthesis and Characterization of Co-ZnO and Evaluation of Its Photocatalytic Activity for Photodegradation of Methyl Orange. ACS Omega. 2021;6:1426-1435.
[CrossRef] [Google Scholar]

[2] Ansari S., Ansari M.S., Satsangee S.P., Jain R., . Bi₂O₃/ZnO nanocomposite: Synthesis, characterizations and its application in electrochemical detection of balofloxacin as an anti-biotic drug. J. Pharm. Anal.. 2021;11:57-67.
[CrossRef] [Google Scholar]

[3] Anwer H., Mahmood A., Lee J., Kim K.H., Park J.W., Yip A.C.K., . Photocatalysts for degradation of dyes in industrial effluents: Opportunities and challenges. Nano Res.. 2019;12:955-972.
[CrossRef] [Google Scholar]

[4] Balachandran S., Swaminathan M., . Facile fabrication of heterostructured Bi₂O₃-ZnO photocatalyst and its enhanced photocatalytic activity. J. Phys. Chem. C. 2012;116:26306-26312.
[CrossRef] [Google Scholar]

[5] Balcha A., Yadav O.P., Dey T., . Photocatalytic degradation of methylene blue dye by zinc oxide nanoparticles obtained from precipitation and sol-gel methods. Environ. Sci. Pollut. Res.. 2016;23:25485-25493.
[CrossRef] [Google Scholar]

[6] Bhaviya Raj R., Umadevi M., Parimaladevi R., . Synergy photodegradation of basic dyes by zno/bi2o3 nanocomposites under visible light irradiation. Iran. J. Chem. Chem. Eng.. 2021;40:1121-1131.
[Google Scholar]

[7] Chen M., Chu W., Beiyuan J., Huang Y., . Enhancement of UV-assisted TiO₂ degradation of ibuprofen using Fenton hybrid process at circumneutral pH. Chin. J. Catal.. 2018;39:701-709.
[CrossRef] [Google Scholar]

[8] Chen M., Yao J., Huang Y., Gong H., Chu W., . Enhanced photocatalytic degradation of ciprofloxacin over Bi₂O₃/(BiO)₂CO₃ heterojunctions: efficiency, kinetics, pathways, mechanisms and toxicity evaluation. Chem. Eng. J.. 2018;334:453-461.
[CrossRef] [Google Scholar]

[9] Ding Y., Zhu L., Huang A., Zhao X., Zhang X., Tang H., . A heterogeneous Co₃O₄-Bi₂O₃ composite catalyst for oxidative degradation of organic pollutants in the presence of peroxymonosulfate. Catal. Sci. Technol.. 2012;2:1977-1984.
[CrossRef] [Google Scholar]

[10] Gan L., Xu L.J., Qian K., Wang Y.D., Jiang F.Y., . Hydrothermal synthesis of magnetic graphene-BiFeO₃ hybrids and their photocatalytic properties. Xinxing Tan Cailiao/New Carbon Materials. 2018;33:221-228.
[Google Scholar]

[11] Hammad A.H., Marzouk M.A., ElBatal H.A., . The Effects of Bi₂O₃ on Optical, FTIR and Thermal Properties of SrO-B₂O₃ Glasses. Silicon. 2016;8:123-131.
[CrossRef] [Google Scholar]

[12] Ho C.-H., Chan C.-H., Huang Y.-S., Tien L.-C., Chao L.-C., . The study of optical band edge property of bismuth oxide nanowires α-Bi₂O₃. Opt. Express. 2013;21:11965.
[CrossRef] [Google Scholar]

[13] Hu L., Zhang G., Liu M., Wang Q., Dong S., Wang P., . Application of nickel foam-supported Co₃O₄-Bi₂O₃ as a heterogeneous catalyst for BPA removal by peroxymonosulfate activation. Sci. Total Environ.. 2019;647:352-361.
[CrossRef] [Google Scholar]

[14] Huang X., Zhang W., Tan Y., Wu J., Gao Y., Tang B., . Facile synthesis of rod-like Bi₂O₃ nanoparticles as an electrode material for pseudocapacitors. Ceram. Int.. 2016;42:2099-2105.
[CrossRef] [Google Scholar]

[15] Huang Y., Liang Y., Rao Y., Zhu D., Cao J.J., Shen Z., Ho W., Lee S.C., . Environment-Friendly Carbon Quantum Dots/ZnFe₂O₄ Photocatalysts: Characterization, Biocompatibility, and Mechanisms for NO Removal. Environ. Sci. Technol.. 2017;51:2924-2933.
[CrossRef] [Google Scholar]

[16] Ilyas, M Saeed M, . Oxidation of benzyl alcohol in liquid phase catalyzed by cobalt oxide. Int. J. Chem. Reactor Eng.. 2010;8:A77.
[CrossRef] [Google Scholar]

[17] Ivanova-Kolcheva V., Sygellou L., Stoyanova M., . Enhanced catalytic degradation of acid orange 7 dye by peroxymonosulfate on Co₃O₄ promoted by Bi₂O₃. Acta Chim. Slov.. 2020;67:609-621.
[Google Scholar]

[18] Iyyapushpam S., Nishanthi S.T., Padiyan D.P., . Synthesis of β-Bi₂O₃ towards the application of photocatalytic degradation of methyl orange and its instability. J. Phys. Chem. Solids. 2015;81:74-78.
[CrossRef] [Google Scholar]

[19] Kaur G., Sharma S., Bansal P., . Visible light responsive heterostructured α-Bi₂O₃/ZnO doped β-Bi₂O₃ photocatalyst for remediation of organic pollutants. Desalin. Water Treat.. 2020;201:349-355.
[CrossRef] [Google Scholar]

[20] Li R., Zhou D., Luo J., Xu W., Li J., Li S., Cheng P., Yuan D., . The urchin-like sphere arrays Co₃O₄ as a bifunctional catalyst for hydrogen evolution reaction and oxygen evolution reaction. J. Power Sources. 2017;341:250-256.
[CrossRef] [Google Scholar]

[21] Li S., Chen J., Hu S., Wang H., Jiang W., Chen X., . Facile construction of novel Bi₂WO₆/Ta₃N₅ Z-scheme heterojunction nanofibers for efficient degradation of harmful pharmaceutical pollutants. Chem. Eng. J.. 2020;402
[CrossRef] [Google Scholar]

[22] Li S., Hu S., Jiang W., Liu Y., Zhou Y., Liu J., Wang Z., . Facile synthesis of cerium oxide nanoparticles decorated flower-like bismuth molybdate for enhanced photocatalytic activity toward organic pollutant degradation. J. Colloid Interface Sci.. 2018;530:171-178.
[CrossRef] [Google Scholar]

[23] Li S., Hu S., Jiang W., Zhang J., Xu K., Wang Z., . In situ construction of WO₃ nanoparticles decorated Bi₂MoO₆ microspheres for boosting photocatalytic degradation of refractory pollutants. J. Colloid Interface Sci.. 2019;556:335-344.
[CrossRef] [Google Scholar]

[24] Li S., Shen X., Liu J., Zhang L., . Synthesis of Ta₃N₅/Bi₂MoO₆ core-shell fiber-shaped heterojunctions as efficient and easily recyclable photocatalysts. Environ. Sci. Nano. 2017;4:1155-1167.
[CrossRef] [Google Scholar]

[25] Li S., Wang C., Cai M., Yang F., Liu Y., Chen J., Zhang P., Li X., Chen X., . Facile fabrication of TaON/Bi2MoO6 core–shell S-scheme heterojunction nanofibers for boosting visible-light catalytic levofloxacin degradation and Cr(VI) reduction. Chem. Eng. J.. 2022;428
[CrossRef] [Google Scholar]

[26] Li S., Wang C., Liu Y., Cai M., Wang Y., Zhang H., Guo Y., Zhao W., Wang Z., Chen X., . Photocatalytic degradation of tetracycline antibiotic by a novel Bi₂Sn₂O₇/Bi₂MoO₆ S-scheme heterojunction: performance, mechanism insight and toxicity assessment. Chem. Eng. J.. 2022;429
[CrossRef] [Google Scholar]

[27] Li S., Wang C., Liu Y., Xue B., Chen J., Wang H., Liu Y.u., . Facile preparation of a novel Bi₂Wo₆/calcined mussel shell composite photocatalyst with enhanced photocatalytic performance. Catalysts. 2020;10:1-11.
[CrossRef] [Google Scholar]

[28] Li S., Wang C., Liu Y., Xue B., Jiang W., Liu Y.u., Mo L., Chen X., . Photocatalytic degradation of antibiotics using a novel Ag/Ag₂S/Bi₂MoO₆ plasmonic p-n heterojunction photocatalyst: mineralization activity, degradation pathways and boosted charge separation mechanism. Chem. Eng. J.. 2021;415
[CrossRef] [Google Scholar]

[29] Li Z., Tang X., Huang G., Luo X., He D., Peng Q., Huang J., Ao M., Liu K., . Bismuth MOFs based hierarchical Co₃O4-Bi₂O₃ composite: an efficient heterogeneous peroxymonosulfate activator for azo dyes degradation. Sep. Purif. Technol.. 2020;242
[CrossRef] [Google Scholar]

[30] Liang J., Zhu G., Liu P., Luo X., Tan C., Jin L., Zhou J., . Synthesis and characterization of Fe-doped β-Bi₂O₃ porous microspheres with enhanced visible light photocatalytic activity. Superlattices Microstruct.. 2014;72:272-282.
[CrossRef] [Google Scholar]

[31] Liu C., Mao S., Shi M., Wang F., Xia M., Chen Q., Ju X., . Peroxymonosulfate activation through 2D/2D Z-scheme CoAl-LDH/BiOBr photocatalyst under visible light for ciprofloxacin degradation. J. Hazard. Mater.. 2021;420
[CrossRef] [Google Scholar]

[32] Liu C., Mao S., Wang H., Wu Y., Wang F., Xia M., Chen Q., . Peroxymonosulfate-assisted for facilitating photocatalytic degradation performance of 2D/2D WO₃/BiOBr S-scheme heterojunction. Chem. Eng. J.. 2022;430
[CrossRef] [Google Scholar]

[33] Liu X., Yang Z., Zhang L., . In-situ fabrication of 3D hierarchical flower-like β-Bi₂O₃@CoO Z-scheme heterojunction for visible-driven simultaneous degradation of multi-pollutants. J. Hazard. Mater.. 2021;403
[CrossRef] [Google Scholar]

[34] Lo Piccolo E., Landi M., . Red-leafed species for urban “greening” in the age of global climate change. J. For. Res.. 2021;32:151-159.
[CrossRef] [Google Scholar]

[35] Luo S., Wang R., Yin J., Jiao T., Chen K., Zou G., Zhang L., Zhou J., Zhang L., Peng Q., . Preparation and dye degradation performances of self-assembled MXene-Co₃O₄ nanocomposites synthesized via solvothermal approach. ACS Omega. 2019;4:3946-3953.
[CrossRef] [Google Scholar]

[36] Ma H., Yang X., Tang X., Cao X., Dai R., . Self-assembled Co-doped β-Bi₂O₃ flower-like structure for enhanced photocatalytic antibacterial effect under visible light. Appl. Surf. Sci.. 2022;572
[CrossRef] [Google Scholar]

[37] Malefane M.E., . Co₃O₄/Bi₄O₅I₂/Bi₅O₇I C-Scheme Heterojunction for Degradation of Organic Pollutants by Light-Emitting Diode Irradiation. ACS Omega 2020
[CrossRef] [Google Scholar]

[38] Manickam M., Ponnuswamy V., Sankar C., Suresh R., Mariappan R., Chandrasekaran J., . The Effect of Solution pH on the Properties of Cobalt Oxide Thin Films Prepared by Nebulizer Spray Pyrolysis Technique. Int. J. Thin Films Sci. Technol.. 2016;5:155-161.
[Google Scholar]

[39] Meng L., Sun Y., Gong H., Wang P., Qiao W.C., Gan L., Xu L.J., . Research progress of the application of graphene-based materials in the treatment of water pollutants. Xinxing Tan Cailiao/New Carbon Materials. 2019;34:220-237.
[CrossRef] [Google Scholar]

[40] Manigandan R., Giribabu K., Suresh R., Vijayalakshmi L., Stephen A., Narayanan V., . Cobalt Oxide Nanoparticles: Characterization and its Electrocatalytic Activity towards Nitrobenzene. Chem. Sci. Trans.. 2013;2
[CrossRef] [Google Scholar]

[41] Nisar A., Saeed M., Muneer M., Usman M., Khan I., . Synthesis and characterization of ZnO decorated reduced graphene oxide (ZnO-rGO) and evaluation of its photocatalytic activity toward photodegradation of methylene blue. Environ. Sci. Pollut. Res.. 2022;29:418-430.
[CrossRef] [Google Scholar]

[42] Rao K.V., Sunandana C.S., . Synthesis and characterization of Co3O₄ nanoparticles. AIP Conf. Proc.. 2008;1003:97-99.
[CrossRef] [Google Scholar]

[43] Saeed M., Ilyas M., Siddique M., . Oxidative degradation of phenol in aqueous medium catalyzed by lab prepared cobalt oxide. J. Chem. Soc. Pak.. 2012;34:626-633.
[Google Scholar]

[44] Saeed, M., Ahmad, A., Boddula, R., Inamuddin, Haq, A. ul, Azhar, A., 2018. Ag@Mn_xO_y: an effective catalyst for photo-degradation of rhodamine B dye. Environ. Chem. Lett. 16, 287-294. doi: 10.1007/s10311-017-0661-z.

[45] Saeed, M., Muneer, M., Haq, A. ul, Akram, N., 2022. Photocatalysis: an effective tool for photodegradation of dyes—a review. Environmental Science and Pollution Research 29, 293–311. https://doi.org/10.1007/s11356-021-16389-7

[46] Song C., Wang L.J., Sun S.M., Wu Y., Xu L.J., Gan L., . Preparation of visible-light photocatalysts of Bi2O₃/Bi embedded in porous carbon from Bi-based metal organic frameworks for highly efficient Rhodamine B removal from water. Xinxing Tan Cailiao/New Carbon Materials. 2020;35:609-618.
[CrossRef] [Google Scholar]

[47] Tang X., Feng Q., Huang J., Liu K., Luo X., Peng Q., . Carbon-coated cobalt oxide porous spheres with improved kinetics and good structural stability for long-life lithium-ion batteries. J. Colloid Interface Sci.. 2018;510:368-375.
[CrossRef] [Google Scholar]

[48] Wang C., Cai M., Liu Y., Yang F., Zhang H., Liu J., Li S., . Facile construction of novel organic–inorganic tetra (4-carboxyphenyl) porphyrin/Bi₂MoO₆ heterojunction for tetracycline degradation: performance, degradation pathways, intermediate toxicity analysis and mechanism insight. J. Colloid Interface Sci.. 2022;605:727-740.
[CrossRef] [Google Scholar]

[49] Wang Z., Wang H., Zeng Z., Zeng G., Xu P., Xiao R., Huang D., Chen X., He L., Zhou C., Yang Y., Wang Z., Wang W., Xiong W., . Metal-organic frameworks derived Bi₂O₂CO₃/porous carbon nitride: A nanosized Z-scheme systems with enhanced photocatalytic activity. Appl. Catal. B. 2020;267
[CrossRef] [Google Scholar]

[50] Xu L., Meng L., Zhang X., Mei X., Guo X., Li W., Wang P., Gan L., . Promoting Fe³⁺/Fe²⁺ cycling under visible light by synergistic interactions between P25 and small amount of Fenton reagents. J. Hazard. Mater.. 2019;379
[CrossRef] [Google Scholar]

[51] Xu Q., Zhang L., Yu J., Wageh S., Al-Ghamdi A.A., Jaroniec M., . Direct Z-scheme photocatalysts: Principles, synthesis, and applications. Mater. Today. 2018;21:1042-1063.
[CrossRef] [Google Scholar]

[52] Zhang L., Ghimire P., Phuriragpitikhon J., Jiang B., Gonçalves A.A.S., Jaroniec M., . Facile formation of metallic bismuth/bismuth oxide heterojunction on porous carbon with enhanced photocatalytic activity. J. Colloid Interface Sci.. 2018;513:82-91.
[CrossRef] [Google Scholar]

[53] Zhang W., Mohamed A.R., Ong W.J., . Z-Scheme Photocatalytic Systems for Carbon Dioxide Reduction: Where Are We Now? Angewandte Chemie - International Edition. 2020;59:22894-22915.
[CrossRef] [Google Scholar]

[54] Zhao Z., Fan J., Deng X., Liu J., . One-step synthesis of phosphorus-doped g-C₃N₄/Co₃O₄ quantum dots from vitamin B₁₂ with enhanced visible-light photocatalytic activity for metronidazole degradation. Chem. Eng. J.. 2019;360:1517-1529.
[CrossRef] [Google Scholar]

[55] Zhong Y.K., Zhou B., Zhang C.J., Wu D., . Effects of surface oxygen functional groups on activated carbon on the adsorption and photocatalytic degradation activities of a TiO₂-AC hybrid for methylene blue and methylene orange. Xinxing Tan Cailiao/New Carbon Materials. 2017;32:460-466.
[CrossRef] [Google Scholar]

[56] Zhu M., Sun Z., Fujitsuka M., Majima T., . Z-Scheme Photocatalytic Water Splitting on a 2D Heterostructure of Black Phosphorus/Bismuth Vanadate Using Visible Light. Angewandte Chemie - International Edition. 2018;57:2160-2164.
[CrossRef] [Google Scholar]

Co3O4-Bi2O3 heterojunction: An effective photocatalyst for photodegradation of rhodamine B dye

Abstract

Abstract

Keywords

Co3O4-Bi2O3

Heterojunction

Photodegradation

Rhodamine B

Kinetics analysis

1 Introduction

2 Experimental

2.1 Synthesis of photocatalyst

2.2 Characterization

2.3 Catalytic activity

3 Results and discussion

3.1 Characterization

3.2 Catalytic activity

3.3 Effect of pH

3.4 Effect of catalyst dose

3.5 Effect of concentration

4 Conclusions

Acknowledgements

Declaration of Competing Interest

References

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Co₃O₄-Bi₂O₃ heterojunction: An effective photocatalyst for photodegradation of rhodamine B dye