BiOBr Heterojunction Research Articles

Construction of Type-II Zn-SnO2/BiOBr Heterojunctions with Dual-oxygen Vacancies for Enhanced Photocatalytic Degradation

Zn-SnO2/BiOBr, a novel heterojunction material for photocatalytic dye degradation, was synthesized successfully using the one-step hydrothermal method. The formation of the heterojunction enhanced the vacancy coupling effect. The photocatalytic experiment results showed that the degradation rate of Rhodamine B (RhB) due to 0.3Zn-SnO2/BiOBr (the heterojunction formed when the molar ratio of Zn-SnO2 to BiOBr was 0.3) within 15 min was 9.27 and 476.9 times that of BiOBr and Zn-SnO2, respectively. Additionally, the degradation rate of basic fuchsin (BF) due to 0.3Zn-SnO2/BiOBr was 4.2 and 21.9 times that of BiOBr and Zn-SnO2, respectively. The significantly improved photocatalytic performance was because many oxygen vacancies in Zn-SnO2/BiOBr collaborated with the type-II heterojunction to promote a narrow bandgap value efficiently, increasing the photogenerated electrons (e–) and hole (h+), an increased charge separation efficiency under visible light, and favored the photocatalytic degradation of dyes.

Construction of novel biochar/g-C3N4/BiOBr heterojunction with S-scheme mechanism for efficient photocatalytic degradation of tetracycline

In this work, a novel biochar/g-C3N4/BiOBr (BCN/BiOBr) S-scheme heterojunction was synthesized for the removal of tetracycline (TC) under visible light. The 0.75-BCN/BiOBr heterojunction exhibited a significantly higher degradation efficiency of TC in wastewater under visible light excitation, achieving about 86.5 % degradation in 72 minutes, which is 2.5 times higher than that of pure g-C3N4. Furthermore, the influence of factors such as pH, dosage of tetracycline and photocatalyst on TC degradation were investigated. Photochemical characterization experiments revealed that the enhanced degradation performance of the BCN/BiOBr heterojunction stemmed from the synergistic effects of adsorption and photocatalysis, providing more active sites to promote the photocatalytic reaction, and accelerating accelerate charge separation and light absorption ability. Meanwhile, the results from the active species indicated that h+, ·OH, and ·O2- play major roles in the degradation process. Additionally, the mechanism research revealed that the photogenerated carriers followed an S-scheme step transfer pathway at the interface of BiOBr and g-C3N4, and the two possible pathways for TC degradation. This provides guidance for improving wastewater treatment using biochar-modified high-efficiency S-scheme photocatalysts.

Construction of 2D/2D protonated g-C3N4/BiOBr heterojunction composite with high photocatalytic degradation performance

In this study, protonated g-C3N4 nanosheets (PCNS) were firstly synthesized through the thermal polymerization of melamine, thermal exfoliating of g-C3N4, and the protonating of g-C3N4 nanosheets. Then, 2D/2D g-C3N4/BiOBr heterojunction composites (PCNSB-X, X = 10, 20, 30, 50, 70, representing the mass percent of PCNS in the composites) were constructed by the in-situ growth of BiOBr nanosheets on the surface of PCNS. PCNSB-X composites showed enhanced light absorption, reduced recombination rate of photogenerated electron-hole pairs, higher photocurrent density and decreased impedance. Their photocatalytic activities toward degrading Rhodamine B (RhB) aqueous solution showed a trend of gradually increasing and then decreasing with the increase of g-C3N4 nanosheet dosage. The optimum photocatalytic performance was achieved by PCNSB-50, who (0.05 g) degraded 98.8% of RhB molecules (100 mL, 20 mg/L) after 60 min of visible light irradiation. Its reaction rate constant (k=0.0717 min−1) was 7.03 and 2.82 times that of pure g-C3N4 nanosheets and pure BiOBr nanosheets, respectively. g-C3N4/BiOBr composites also exhibited excellent recyclability and stability for degrading RhB. This work provides a feasible method for synthesizing g-C3N4/BiOBr composites with excellent photocatalytic performance.

Ultrasensitive and specific photoelectrochemical sensor for hydrogen peroxide detection based on pillar[5]arene-functionalized Au nanoparticles and MWNTs hybrid BiOBr heterojunction.

A photoelectrochemical sensor for target detection of hydrogen peroxide was designed based on a new heterojunction nanocomposite which was sulfhydryl-borate ester-modified A1/B1-type pillar[5]arene (BP5)-functionalized Au NPs and multi-walled carbon nanotubes hybridized with bismuth bromide oxide (Au@BP5/MWNTs-BiOBr). The specific sensor was based on the direct induction of oxidation by hydrogen peroxide of the borate ester group of pillar[5]arene. Additionally, the local surface plasmon resonance (LSPR) of Au NPs enhanced visible light capture, the host-guest complexation of BP5 with H2O2 enhanced photocurrent response, the layer-by-layer stacked nanoflower structure of BiOBr provided large specific surface area with more active sites, and the conductivity of MWNTs enhanced the charge separation efficiency and significantly improves the stability of PEC. Their synthesis effect significantly increased the photocurrent signal and further enhanced the detection result. Under the optimal conditions, the linear concentration range of H2O2 detected by the Au@BP5/MWNTs-BiOBr sensor was from 1 to 60pmol/L. The limit of detection (LOD) and the limit of quantification (LOQ) of the method were 0.333pmol/L and 1pmol/L, respectively, and the sensitivity was 6.471pmol/L. Importantly, the PEC sensor has good stability, reproducibility, and interference resistance and can be used for the detection of hydrogen peroxide in real cells.

Design of Z-scheme UIO-66-NH2/BiOBr heterojunctions for efficient visible-light-driven selenite removal from water: Performance and mechanism studies

Excess existence of the selenite (Se(IV)) is hazardous to water resources. Therefore, a need still exists for the removal of Se(IV) from the wastewater in the renewable, environmentally friendly, and low-cost way. This paper presents a novel way to design a Z-type heterojunction of UIO-66-NH2/BiOBr using co-precipitation technology for efficiently removal of Se(IV) from wastewater using the adsorption-visible photocatalytic synergy. The UIO-66-NH2 presents an enhanced adsorption of Se(IV) due to the expose of abundant linker defects, as the active sites. The Z-type heterojunction (UB-2) showed 96.4% removal of Se(IV) at an initial concentration of 100 mg/L under visible light conditions due to its higher charge transfer capacity and electron-hole separation ability. The photocatalytic removal rate of UB-2 toward Se(IV) was 4.12 times and 9.93 times higher than that of UIO-66-NH2 and BiOBr, respectively. UB-2 could be reused and showed a good removal capacity in real-world water samples. The used UB-2 was superior to the nano-selenium in the scavenging of superoxide radical and DPPH, revealing a potential of biological antioxidant. This work will be beneficial for the efficient decontamination of Se(IV)-containing wastewater.

NH2-UiO-66 modification BiOBr enhancement photoreduction CO2 to CO

As a typical semiconductor catalyst, BiOBr has an advisable bandgap, superior light absorption properties, and a unique laminated structure. However, the slow electron-hole separation rate results in poor CO2 reduction performance. To enhance the photocatalytic efficiency of BiOBr, this study constructs BiOBr heterojunctions with Lewis basic groups by loading NH2-UiO-66 on BiOBr. The BiOBr/NH2-UiO-66 heterojunction have been built and possess stronger light response, larger specific surface area and electron-hole separation efficiency compared to pure BiOBr and NH2-UiO-66. The optimal BiOBr/NH2-UiO-66 displays that the CO yield is 9.19 μmol g-1h−1, which is 4 times higher than pure BiOBr.

Boron nitride nanosheets modified BiOBr photocatalysts for promoting photocatalytic removal of tetracycline under visible light irradiation

A series of BN/BiOBr heterojunctions was constructed using in situ hydrothermal-precipitation method and was employed to remove the tetracycline molecules in aqueous solution. The rate of photocatalytic degradation efficiency of tetracycline by 0.05BN/BiOBr was ensured to be more excellent than that by BiOBr. The heterojunciton fabricated between BN and BiOBr enforced an internal electrons transfer from BiOBr to BN, which remarkably inhibited charge recombination. The major reactive species involved in the photocatalysis system were found to be hydroxyl radicals (•OH) and photo-holes (h+), which was verified by the scavenger tests. 0.05-BN/BiOBr heterojunctions showed remarkable reusability and still could degrade 89.25% of tetracycline after four consecutive cycles. According to the characterization and experimental results, a plausible enhanced photocatalytic mechanism was put forward. This work provided the guidance for rational designing heterojunctions with remarkable performance towards antibiotics elimination from wastewater.

Z-scheme Fe@Fe2O3/BiOBr heterojunction with efficient carrier separation for enhanced heterogeneous photo-Fenton activity of tetracycline degradation: Fe2+ regeneration, mechanism insight and toxicity evaluation

The recombination of photogenerated carrier leads to inefficient Fe2+ regeneration, which limits the extensive application of heterogeneous photo-Fenton. Here, a novel Fe@Fe2O3/BiOBr catalyst with Z-scheme heterojunction structure is designed, and the establishment of the Z-scheme heterojunction facilitates the separation and transfer of photogenerated carrier and maintains the superior redox capability of the system. As-prepared Fe@Fe2O3/BiOBr catalyst exhibits outstanding catalytic performance and stability, especially for the optimum composite FFB-3, its degradation efficiency of tetracycline (TC) achieves 98.22% and the mineralization degree reaches 59.48% within 90 min under natural pH. The preeminent catalytic efficiency benefited from the synergistic of heterogeneous photo-Fenton and Z-scheme carriers transfer mechanism, where Fe2+ regeneration was achieved by photogenerated electrons, and increased hydroxyl radicals were produced with the participation of H2O2 in-situ generated. The results of free-radical scavenging experiment and ESR illustrated that •OH, •O2−, 1O2 and h+ were active species participating in TC degradation. Furthermore, the TC degradation paths were proposed according to LC-MS, and the toxicity evaluation result showed that the toxicity of TC solutions was markedly decreased after degradation. This study provides an innovative strategy for heterogeneous photo-Fenton degradation of antibiotic contaminations by constructing Z-scheme heterojunctions.

The Z-Scheme MIL-88B(Fe)/BiOBr Heterojunction Promotes Fe(III)/Fe(II) Cycling and Photocatalytic-Fenton-Like Synergistically Enhances the Degradation of Ciprofloxacin.

The Z-scheme MIL-88B/BiOBr (referred to as MxBy, whereas x and y are the mass of MIL-88B(Fe) and BiOBr) heterojunction photocatalysts are successfully prepared by a facile ball milling method. By adding low concentration H2O2 under visible light irradiation, the Z-scheme heterojunction and photocatalytic-Fenton-like reaction synergistically enhance the degradation and mineralization of ciprofloxacin (CIP). Among them, M50B150 showed efficient photodegradation efficiency and excellent cycling stability, with 94.6% removal of CIP (10mgL-1) by M50B150 (0.2gL-1) under 90min of visible light. In the MxBy heterojunctions, the rapid transfer of photo-generated electrons not only directly decomposed H2O2 to generate ·OH, but also improved the cycle of Fe3+/Fe2+ pairs, which facilitated the reaction with H2O2 to generate ·OH and ·O2 - radicals. In addition, the effects of photocatalyst dosages, pH of CIP solution, and coexisting substances on CIP removal are systematically investigated. It is found that the photocatalytic- Fenton-like reaction can be carried out at a pH close to neutral conditions. Finally, the charge transfer mechanism of the Z-scheme is verified by electron spin resonance (ESR) signals. The ecotoxicity of CIP degradation products is estimated by the T.E.S.T tool, indicating that the constructed photocatalysis-Fenton-like system is a green wastewater treatment technology.

In-situ construction of Z-scheme 2D/2D g-C3N4/BiOBr heterojunction with enhanced photocatalytic CO2 reduction

A novel series of g-C3N4/BiOBr (CN/BOB) Z-scheme heterojunction catalysts with two-dimensional/two-dimensional (2D/2D) morphology were synthesized by an in-situ hydrolysis method for photocatalytic CO2 reduction. Without adding any sacrificial agents or co-catalysts, the optimal CN/BOB heterostructure exhibits a boosted CO generation rate of 20.1 μmol·g-1·h-1 under the simulated solar light irradiation, severally being 1.7 and 3.7 times that of pristine BiOBr and g-C3N4. The enhanced performance principally benefit from the 2D/2D microstructure and Z-scheme heterojunction of photocatalysts. The intimate contact of 2D/2D morphology signifies more transmission channels and shorter transfer interface distance of photogenerated charges. While relevant characterizations and first-principles calculations jointly demonstrate that the Z-scheme heterojunction could significantly accelerate the spatial separation and transfer of photo-induced carriers, and evidently promote the redox ability of photocatalysts. The research furnishes a novel strategy to construct a promising bismuth oxyhalide based heterojunction catalyst for the application of photocatalytic CO2 reduction.

Unveiling efficient S-scheme charge carrier transfer in hierarchical BiOBr/TiO2 heterojunction photocatalysts.

The construction of a potential heterojunction catalyst with proper interface alignment has become a hot topic in the scientific community to effectively utilize solar energy. In this work, a one-dimensional TiO2 nanofiber/BiOBr S-scheme heterojunction was synthesized, and charge carrier dynamics within the interface channel were explored. In addition, we incorporated mixed phase TiO2 with point defects and oxygen vacancies, which greatly promoted the initial band edge shift from the UV region. Upon the addition of BiOBr, absorption in the visible light region of the electromagnetic (EM) spectrum was observed with a decrease in the optical band gap value. The optimized BiOBr heterojunction (BTNF1.5) revealed a higher photocatalytic RhB dye degradation efficiency due to the efficient generation and separation of charge carriers upon light irradiation. The optimum sample BTNF1.5 showed a high degradation efficiency of 98.4% with a rate constant of 47.1 min-1 at 8 min of visible light irradiation, which is double than that of the pure TiO2. Electrochemical analysis, time-resolved photoluminescence and Kelvin probe measurement revealed an S-scheme charge-transfer mechanism within the BiOBr/TiO2 system. This work provides a strategy for the facile synthesis of heterojunction photocatalysts exhibiting exceptional catalytic performance.

Facile synthesis of a 2D/3D Z-scheme Cu-g-C3N4/BiOBr heterojunction for enhanced photocatalytic degradation of ciprofloxacin under visible light irradiation

A 2D/3D Z-scheme Cu-doped-g-C3N4/BiOBr (CuCNB) heterojunction was fabricated using a facile solvothermal technique for enhanced photocatalytic degradation of ciprofloxacin (CIP). It is believed that a Z-scheme heterojunction is formed between BiOBr and Cu-doped g-C3N4 (Cu-g-C3N4) based on Mott-Schottky analysis. Hence, the as-prepared nanocomposite exhibits an excellent charge carrier separation ability, a broadband and intense visible-light absorption potential, and a strong redox capacity. Under optimum conditions (pH 6.2 and catalyst dose of 0.75 g L−1), a degradation efficiency of approximately 91.5 % is achieved after 240 min of visible-light irradiation by using the CuCNB photocatalyst, which is nearly 1.22, 2.55, and 1.31 times higher than pristine BiOBr, Cu-g-C3N4, and BiOBr-Cu-g-C3N4 mixture, respectively. Radical quenching experiments and electron paramagnetic resonance measurements confirm that the net contribution of various oxidative species decreases in the order of hydroxyl radicals < superoxide anions < holes. A toxicity assessment of CuCNB, as well as the end products of CIP degradation, revealed that both the photocatalyst as well as the photocatalysis by-products were unlikely to inflict any negative impact on the environment. Additionally, the CuCNB photocatalyst showed good stability and acceptable photocatalytic activity over multiple cycles. Further, the practical utility of CuCNB was assessed in different actual water samples. It was observed that the degradation efficiency was lower in wastewater in comparison to surface water and tap water. Overall, the findings of this research offer new foresights into constructing a Z-scheme heterojunction photocatalysts with excellent stability and performance for removing emerging pollutants from aqueous matrices.

Construction of Z-scheme Cu-CeO2/BiOBr heterojunction for enhanced photocatalytic degradation of sulfathiazole

The utilization of an efficient photocatalyst is crucial for the photocatalytic degradation of antibiotics in water through visible light, which is an imperative requirement for the remediation of water environments. In this study, a novel Cu-CeO2/BiOBr Z-type heterojunction was synthesized by calcination and hydrothermal methods, and the degradation rate of sulfathiazole (STZ) antibiotic solution was studied using simulated illumination (300 W xenon lamp). The results indicated that 3% Cu-CeO2/BiOBr achieved a degradation rate of 92.3% within 90 min when treating 20 mg/L STZ solution, demonstrating its potential for practical water treatment applications. Characterization using various chemical instruments revealed that 3% Cu-CeO2/BiOBr exhibited the lowest electron-hole recombination rate and electron transfer resistance. Furthermore, the utilization of ESR data and quenching experiments has substantiated the involvement of hydroxyl radicals (•OH) and superoxide radicals (•O2−) as the primary active species. Consequently, a plausible degradation mechanism has been inferred. These findings offer a prospective approach for the development of heterojunction materials with appropriate band matching.

Facile synthesis of nanometer-sized NH2-MIL-101(Fe) decorated BiOBr hybrids for efficient Cr(VI) photoreduction

Using a simple oil bath approach, a nanometer-sized NH2-MIL-101(Fe) (NMF) adorned BiOBr heterojunction photocatalyst was effectively created. Compared with the traditional solvothermal method, the synthesis time is shortened by 10 times. Furthermore, nanometer-sized granular NMF particles are uniformly dispersed on BiOBr surface to form plenty of NMF/BiOBr heterojunctions due to chemical action of oxygen vacancies and –NH2 groups. As a result, the as-synthesized NMF/BiOBr photocatalysts exhibit the improved Cr(VI) reduction performance. In 60 min, the 3%NMF/BiOBr heterostructure reaches a maximum Cr(VI) photoreduction efficiency of 99 %. In the 3%NMF/BiOBr heterostructure, Cr(VI) photoreduction occurs at an apparent rate constant that is 7.6 times higher than that of pure BiOBr and 5.44 times higher than that of NMF. The microstructures and photoelectrochemical characteristics of NMF/BiOBr heterostructures were analyzed through state-of-the-art characterization methods. The results show that charge separation and transfer are promoted by the development of heterojunction, which is brought about by the chemical interaction between oxygen vacancies and –NH2 groups. Furthermore, the intimate contact bonding provides electron transport pathways, considerably increasing photocatalytic activity.

Dramatically improved piezo-photocatalytic activity in PVDF@Bi2MoO6/BiOBr composite films via constructing built-in polarization field in heterojunctions

The coupling effect of piezo-photocatalytic technology is well demonstrated as a promising strategy for effective degradation of organic pollutants. However, the catalytic efficiency is dramatically limited by the undesirable neutralization of photogenerated electron-hole pairs. Herein, PVDF@Bi2MoO6/BiOBr heterojunction was designed elaborately to boosting their piezo-photocatalytic activity by built-in polarization field and controlled carrier transfer. The composite film presents excellent degradation performance of methyl orange (MO, 15 mg/L) (98.99%, 120 min) under the simultaneous ultrasonic vibration and visible light irradiation, which is around 2 and 3.1 times than that of individual piezoelectric and photocatalytic process. The improved piezo-photocatalytic capability could be attributed to the enhanced built-in piezoelectric field that generated by the vibration of p-type BiOBr nanosheets. The construction of piezoelectric polarization reduces the recombination efficiency of photogenerated carriers at the p-n heterojunction interface, thereby dramatically improving the catalytic efficiency. This work proposes and demonstrates the very positive role of dual piezoelectricity in modulating the photocatalytic efficiency in semiconductors, which provides a new paradigm for the further development of highly-efficient piezo-photocatalysts to be applied in environmental purification and wastewater treatment.

Novel through-holes g-C3N4/BiOBr S-scheme heterojunction: Charge relocation mechanism and DFT insights

A novel multiscale through-holes g-C3N4/BiOBr S-scheme heterojunction with homogeneous morphology was fabricated via a solvothermal method. Notably, the prepared through-holes g-C3N4 yielded a subband gap (2.11 eV) attributed to the fracture and reorganization of triazine ring units, leading to a narrow band gap complex. Photocatalyst A-2 (2.73 eV) was significantly broadened at the absorption edge. A reasonable S-scheme heterojunction charge relocation mechanism was demonstrated based on active species trapping experiments, atomic force microscope (AFM) equipped with a Kelvin probe force microscope (KPFM), and density functional theoretical (DFT) theoretical calculations. The S-scheme g-C3N4/BiOBr heterojunction and the constructed internal electric field facilitate the retention of high redox properties and facilitated charge relocation. Hence, the synergistic interaction between the S-scheme heterojunction and through-holes structure enabled specimens to be exhibited high-efficiency degradation activity. The degradation efficiency of photocatalyst A-2 for TC·HCL and RhB was 94.5% (60 min) and 99.9% (30 min), respectively. At pH = 5.1, the TC·HCL photoreaction time was reduced to 30 min, whereas at pH = 2.3, the RhB photoreaction time was shortened to 15 min. Five repeatable recovery tests still maintain excellent stability. This work contributes new insights into the charge relocation mechanism of S-scheme heterojunction high-efficiency photocatalysts.

S-scheme P-doped g-C3N4/BiOBr heterojunction with oxygen vacancy for efficient photocatalytic degradation of phenanthrene: Enhance molecular oxygen activation and mechanism insights

S-scheme heterojunction photocatalysts, renowned for their efficient charge separation and strong redox properties, have gained considerable attention in pollutant remediation. Hence, a dual-active site S-scheme P-doped g-C3N4/BiOBr with oxygen vacancy (PCN/BiOBr-OV) was synthesized. The optimized PCN/BiOBr-OV(2:1) exhibited an impressive degradation rate of 99.2% (kobs = 0.04048 min−1) and superior efficiency for various water conditions. Synergistic effects resulting from P-doping and oxygen vacancy (OV) enhanced charge transfer and promoted S-scheme heterojunction generation. The S-scheme charge transfer pathway in PCN/BiOBr-OV was validated using in-situ irradiation X-ray photoelectron spectroscopy (in-situ irradiation XPS). Experimental results and density functional theory (DFT) calculations provided direct evidence supporting the role of P-doping and OV in facilitating water and oxygen adsorption and activation at dual-active sites, leading to the generation of active species (h+, OH, and O2▪−). Quantum mechanical theory and intermediate product analysis effectively elucidated the ring-opening process of PHE. The highly efficient PCN/BiOBr-OV photocatalyst represents a promising strategy for the environmental remediation of PHE.

Construction of UiO-66-NH2/BiOBr heterojunctions on carbon fiber cloth as macroscale photocatalyst for purifying antibiotics

Metal-Organic Frameworks (MOFs) as a novel semiconductor-like material with high adsorption were used to combine with other efficient semiconductors to enhance the adsorption capacity and photocatalytic activity for removing antibiotics from aqueous solutions. In addition, most of the efficient photocatalysts are in powder-shaped, making recycling problematic. To solve the above problems, with macroscale carbon fiber cloth (CFC) as the substrate, Zr-based MOFs (UiO-66-NH2) as a model material with ultra-high specific area and BiOBr as an efficient semiconductor with irregular sheet structure were synthesized sequentially by a solvothermal method and dip-coating process. The prepared CFC/UiO-66-NH2/BiOBr exhibits strong adsorption of 65.4% levofloxacin (LVFX) or 16.8% ciprofloxacin (CIP) within 60 min in dark, and excellent degradation of 92.2% LVFX or 86.4% CIP under visible-light irradiation over a period of 120min. Additionally, after 4 cycles of visible-light irradiation, the macroscale CFC/UiO-66-NH2/BiOBr exhibits stable removal efficiency of antibiotics. Using low-cost CFC as substrate, CFC/UiO-66-NH2/BiOBr shows high efficiency and recyclability in removing antibiotics from polluted wastewater, offering guidance for developing highly effective photocatalysts on a large scale through methods like calcination and sol-gel synthesis. Therefore, the macroscale CFC/UiO-66-NH2/BiOBr has great potential for purifying antibiotics under visible-light illumination, presenting a practical solution for sustainable development.

Thickness Modification of BiOBr Nanosheets by Sn-TiO2 for Enhanced Photocatalytic Degradation of Antibiotics

Modification of morphological engineering to enhance photocatalytic activity has been considered an effective strategy. However, effective modification of the catalyst nanosheet thickness remains a difficult challenge to control. Here, we have synthesized Sn-TiO2/BiOBr composite photocatalysts by a one-pot method. With the addition of Sn-TiO2, the flakes of BiOBr gradually became thinner, resulting in more surface reaction site, and Sn-TiO2 clearly increased the adsorption capacity of the composite catalyst. The degradation efficiency of the prepared Sn-TiO2/BiOBr (the atomic ratio of titanium/bismuth 1:1) was 98% and 80% for TC-HCl and CIP, respectively, showing good photocatalytic performance. Furthermore, the radical trapping experiments revealed that h+ and •O2– play an important role in the Sn-TiO2/BiOBr system. Photoelectrochemical tests and photoluminescence confirm that the thin sheets can significantly improve carrier migration efficiency in Sn-TiO2/BiOBr heterojunctions. Finally, the degradation mechanism of the Sn-TiO2/BiOBr system was elucidated using UV-DRs and Mott–Schottky curves. Experimental analysis shows that modulating the thickness of BiOBr nanosheets with Sn-TiO2 can promote the exposure of surface reaction sites, can enhance their light adsorption ability and carrier mobility, and is a promising method for improving photocatalytic efficiency.

Insight into the mechanism and toxicity assessment of a novel Co3O4/BiOBr p-n heterojunction driven by sunlight for efficient degradation of glyphosate

The environmental stresses posed by glyphosate, an organic phosphorus herbicide with inert CP and CN bonds, necessitate its effective degradation. Herein, we present a novel p-type Co3O4/n-type BiOBr heterojunction (COBB) photocatalyst as an efficient solution for this challenge. Owing to the built-in electric field as well as the synergistic matching band potentials of the p-Co3O4 and n-BiOBr, the COBB considerably enhances the separation efficiency and transfer rates of photogenerated carriers. As a result, it displays remarkable activity in degrading 16.9 mg/L of glyphosate under simulated sunlight with 88.5 % efficiency, outperforming both the pure Co3O4 and BiOBr by 51.8 and 3.3 times, respectively. In addition, COBB also demonstrates promising performance under natural sunlight and maintains a high level of stability in four cycles. Furthermore, intermediate product and toxicity analyses illustrate that the toxicity of glyphosate is greatly reduced in the COBB system. Altogether, this study provides renewed opportunities for the use of heterojunction photocatalysts in natural environments.