Semiconductor Photocatalysis Research Articles

Pioneering SubPc-Br/CdS S-scheme heterojunctions: Achieving superior photocatalytic oxidation through enhanced radical synergy and photocorrosion mitigation

For the efficient harnessing of solar energy and mitigation of environmental pollution, the development and application of semiconductor photocatalysis technology is paramount. Herein, a novel SubPc-Br/CdS supramolecular array with an S-scheme heterojunction was synthesized through the intermolecular π-stacked self-assembly of subphthalocyanine (SubPc-Br) and nanometer cadmium sulfide (CdS). This self-assembly system features a highly structured architecture and excellent stability. Experiments and ground-state differential charge calculations demonstrate that SubPc-Br and CdS form a built-in electric field during the self-assembly process, a critical factor in promoting the dissociation of electrons and holes. Additionally, this study utilized time-dependent density functional theory (TDDFT) to simulate the dynamic adsorption behavior of excited oxygen molecules on the SubPc-Br/CdS interface for the first time. The analysis of molecular charge differential density under different excited states proved that the addition of SubPc-Br molecules not only improves the photocorrosion resistance of CdS in an O2 adsorption environment but also enhances the production of advanced reactive oxygen species under the synergistic action of h+ and ·O2–. When subjected to visible light, the degradation efficiency of minocycline (MC) achieved 96.8% within 60 min and maintained 80.3% after 5 cycles. In summary, this study highlights the feasibility of creating advanced S-scheme heterojunction photocatalysts through the strategic incorporation of organic supramolecules with semiconductor catalysts.

Single-Particle Fluorescence Spectroscopy for Elucidating Charge Transfer and Catalytic Mechanisms on Nanophotocatalysts.

Photocatalysis is a cost-effective approach to producing renewable energy. A thorough comprehension of carrier separation at the micronano level is crucial for enhancing the photochemical conversion capabilities of photocatalysts. However, the heterogeneity of photocatalyst nanoparticles and complex charge migration processes limit the profound understanding of photocatalytic reaction mechanisms. By establishing the precise interrelationship between microscopic properties and photophysical behaviors of photocatalysts, single-particle fluorescence spectroscopy can elucidate the carrier separation and catalytic mechanism of the photocatalysts in situ, which provides perspectives for improving the photocatalytic efficiency. This Review primarily focuses on the basic principles and advantages of single-particle fluorescence spectroscopy and its progress in the study of plasmonic and semiconductor photocatalysis, especially emphasizing its importance in understanding the charge separation and photocatalytic reaction mechanism, which offers scientific guidance for designing efficient photocatalytic systems. Finally, we summarize and forecast the future development prospects of single-particle fluorescence spectroscopy technology, especially the insights into its technological upgrading.

A-Site Doping Promotes CO2 Activation and Prolongs Charge Carrier Lifetimes in SrTiO3: Insight from Quantum Dynamics.

Using time-dependent density functional theory and nonadiabatic molecular dynamics, we systematically investigated the effect of A-site doping on the CO2 activation and charge carrier lifetimes in SrTiO3(STO). Our simulations revealed that A-site doping significantly enhances the chemical adsorption of CO2 on SrTiO3 surfaces, which is beneficial for promoting CO2 activation. Moreover, we found that A-site doping can efficiently stabilize the lowest unoccupied molecular orbital (LUMO) of CO2 near the conduction band minimum of STO, promoting the photogenerated electron transfer from the conduction band of STO to the CO2 LUMO. Importantly, A-site doping causes a significant nonadiabatic coupling reduction and prolongs the charge recombination time by a factor of 1.86 compared to the pristine STO. Our study clarifies the influencing mechanism of A-site doping on CO2 activation and charge carrier lifetimes and suggests important principles for the design of high-performance photocatalytic semiconductors.

Photocatalysis of Adsorbed Catechol on Degussa P25 TiO2 at the Air-Solid Interface.

Semiconductor photocatalysis with commercial TiO2 (Degussa P25) has shown significant potential in water treatment of organic pollutants. However, the photoinduced reactions of adsorbed catechol, a phenolic air pollutant from biomass burning and combustion emissions, at the air-solid interface of TiO2 remain unexplored. Herein we examine the photocatalytic decay of catechol in the presence of water vapor, which acts as an electron acceptor. Experiments under variable cut-off wavelengths of irradiation (λcut-off ≥ 320, 400, and 515 nm) distinguish the mechanistic contribution of a ligand-to-metal charge-transfer (LMCT) complex of surface chemisorbed catechol on TiO2. The LMCT complex injects electrons into the conduction band of TiO2 from the highest occupied molecular orbital of catechol by visible light (≥2.11 eV) excitation. The deconvolution of diffuse reflectance UV-visible spectral bands from LMCT complexes of TiO2 with catechol, o-semiquinone radical, and quinone and the quantification of the evolving gaseous products follow a consecutive kinetic model. CO2(g) and CO(g) final oxidation products are monitored by gas chromatography and Fourier-transform infrared spectroscopy. The apparent quantum efficiency at variable λcut-off are determined for reactant loss (Φ- TiO2/catechol = 0.79 ± 0.19) and product growth ΦCO2 = 0.76 ± 0.08). Spectroscopic and electrochemical measurements reveal the energy band diagram for the LMCT of TiO2/catechol. Two photocatalytic mechanisms are analyzed based on chemical transformations and environmental relevance.

Band gap engineering of ADG/NiO nanocomposite and applications for photocatalytic reduction of nitrogen and photo-oxidation of dyes

The use of solar-driven semiconductor photocatalysis to solve energy and environmental issues is an intriguing and difficult subject. As a consequence, various types of photocatalysts have been developed subsequently to fulfill the requirements of photocatalysis.Since graphene was discovered, materials based on graphene have garnered considerable interest. The aloe-vera derived (ADG)/nickel oxide (NiO) nanocomposite is a notable example of a graphene derivative.The uniform structure of graphene fibre is altered by nickel oxide(NiO) which tunes its band gap and causes electronic arrangements within graphene that is requiste for photocatalysis. Herein, we have used a one-pot chemical approach to design aloe vera-derived graphene/nickel oxide nanocomposites (ADG/NiO), a novel photocatalyst that show high molar absorbance, suitable band gap of 2.68 eV, good photo-stability and reusability. Under solar light irradiation, the ADG/NiO nanocomposite exhibited remarkable photocatalytic activity. It effectively fixed nitrogen into ammonia with an apparent quantum efficiency(AQE) of 0.64% and efficiently photo-oxidized dyes. Specifically, it achieved a dye removal efficiency of 94.2% for methylene blue (MB) and 86.41% for Eosin-B, converting them into harmless inorganic species like CO2 and H2O within just 90 minutes. The cost-effective ADG/NiO nanocomposite shows significant potential as a photocatalyst activated by solar light for practical applications such as the selective generation of NH3 and the purification of industrial wastewater containing dyes.

Facilitating exciton dissociation in conjugated microporous polymers for photocatalytic degradation of tetracycline via a gradient N doping strategy

As a leading green wastewater treatment technology, organic semiconductor photocatalysis for tetracycline (TC) degradation is widely recognized but currently constrained by excessive exciton binding energies and rapid charge recombination. In this work, conjugated microporous polymers (CMPs) with five-membered heterocyclic ring have been fabricated by gradient doping of nitrogen at the monomer level. It demonstrates satisfactory photocatalytic performance, with thiadiazole introduced into the unit, achieving a TC removal rate of 95.6% within 30 min under visible light. The underlying origin of the preferable property lies in the lower exciton binding energy (Eb) with the assistance of the donor–acceptor (D-A) structure constructed by thiadiazole monomer and triazine skeleton. Density Functional Theory (DFT) calculations reveal that this five-membered heterocyclic structure can appropriately regulate the local charge distribution and increase the dipole moment, thus accelerating the migration dynamics of charge carriers in the degradation process. This study provides a novel insight into the modulation of polymer exciton Eb and enlightens the designation of metal-free photocatalysts based on antibiotic degradation.

Study of the interaction between low density polyethylene and TiO2 in different environments. Influence of the presence and absence of radiation, and of the atmosphere (O2, N2 or Ar)

In the process of photocatalytic degradation of plastics, the surface interaction between the plastic material and the photocatalyst results crucial. The present work focuses on using a specific TiO2 photocatalytic semiconductor whose hierarchical structure favours the interaction with low density polyethylene (LDPE), a key component in plastics. An exhaustive study of the nature of this interaction is conducted, analysing the influence of the atmosphere and radiation. The results obtained indicate that the observed interaction can be modulated by controlling the atmosphere, evolving into a degradation process whose mechanism also depends on the absence or the presence of light. This point is particularly relevant as it highlights the dual nature of TiO2 as both photocatalyst and catalyst.

Recent Progress of Three-Dimensional Graphene-Based Composites for Photocatalysis.

Converting solar energy into fuels/chemicals through photochemical approaches holds significant promise for addressing global energy demands. Currently, semiconductor photocatalysis combined with redox techniques has been intensively researched in pollutant degradation and secondary energy generation owing to its dual advantages of oxidizability and reducibility; however, challenges remain, particularly with improving conversion efficiency. Since graphene's initial introduction in 2004, three-dimensional (3D) graphene-based photocatalysts have garnered considerable attention due to their exceptional properties, such as their large specific surface area, abundant pore structure, diverse surface chemistry, adjustable band gap, and high electrical conductivity. Herein, this review provides an in-depth analysis of the commonly used photocatalysts based on 3D graphene, outlining their construction strategies and recent applications in photocatalytic degradation of organic pollutants, H2 evolution, and CO2 reduction. Additionally, the paper explores the multifaceted roles that 3D graphene plays in enhancing photocatalytic performance. By offering a comprehensive overview, we hope to highlight the potential of 3D graphene as an environmentally beneficial material and to inspire the development of more efficient, versatile graphene-based aerogel photocatalysts for future applications.

Enhanced hydrogen evolution performance of twinned Mn0.65Cd0.35S with Zn-doped cadmium selenide under visible light irradiation

The cadmium manganese sulfide, despite being recognized as a highly efficient photocatalytic semiconductor for hydrogen evolution, faces significant challenges in terms of charge recombination when used solely as a catalyst for photocatalytic hydrogen production. The construction of heterojunction photocatalysts is regarded as one of the effective strategies to enhance the efficiency of photocatalytic hydrogen production. In this work, Zn-doped CdSe was adopted to enhance the photocatalytic active sites of the twinned Mn0.65Cd0.35S. As results, the photocatalytic hydrogen evolution of Zn–CdSe-1/T-MCS-40 can reach approximately 47447.15 μmol g−1 after 5 h, representing a 15 times increase compared to Mn0.65Cd0.35S. Besides, the hydrogen evolution rate shows almost no significant attenuation after four consecutive cycles (20 h). The significant achievement can be largely attributed to the successful construction of an S-scheme heterojunction of Zn–CdSe-1/T-MCS-40, which effectively minimized the charge transfer distance and suppressed the recombination of photo-generated electron-hole pairs. Additionally, the incorporation of Zn-doped CdSe significantly expands the response range to visible light, thereby providing a conceptual framework for advancing the design of solar-to-chemical energy conversion and effectively guiding the fabrication of metal sulfide-based photocatalytic heterojunctions.

Novel PtCu/MIL-101(Cr) for efficient degradation of bisphenol A: Photothermal synergism promoted by the localized surface plasmon resonance effect

Semiconductor photocatalysis is one of the most useful methods to solve environmental pollution problems. Herein, nanomaterial PtCu/MIL-101(Cr) was produced by an improved hydrothermal technique. The composite exhibited excellent photocatalytic performance with 99.7 % BPA degradation under 100 min visible light irradiation. First, the PtCu alloy has the effect of the local surface plasmon resonance effect, which can convert the photons to hot electrons and increase the reaction temperature. The synergistic effect (1+1>2) between photocatalysis and thermocatalysis significantly improved the photocatalytic efficiency. Second, the bimetallic alloying lowered the metals' work function and reduced the Schottky barrier between the PtCu alloy and MIL-101(Cr), which effectively promoted the carrier transfer. The ·O2-, ·OH and h+ were dominant reactive substances in the degradation process. The intermediates and degradation pathways of BPA were analyzed by 3D-EEM. The reaction mechanism was proposed based on theoretical calculations and experimental analysis. This work provides new directions for designing photothermal synergistic green catalysts and purifying the environment.

Ag doped TiO2 anchored on metal free g-C3N4 for enhanced solar light activated photodegradation of a dye

Heterogeneous semiconductor photocatalysis has attracted researcher's attention in wastewater treatment owing to the improved surface area, optical properties, and charge transfer rate for boosted degradation of organic pollutants. Thus, the g-C3N4/Ag/TiO2 was prepared following a hydrothermal route for the degradation of azo dye tartrazine (TA) used as a food colourant under solar light. Before application, the composite and pristine materials were interrogated for physicochemical and structural properties using SEM, TEM, EDS, XPS, XRD, UV–vis DRS, PL, BET, Raman, and FTIR spectroscopy. The PL and electrochemical analysis revealed that the CNAT composite had a high charge transfer rate that was coupled with low charge carrier complexation. The degradation efficiency of 91 % was realized in 180 min and the rate of pseudo-first-order kinetics of 0.01143 min−1 was obtained. The CNAT catalyst also displayed high removal efficiency towards a cocktail of naproxen (NPX) and TA. The improved removal efficiencies stem from increased visible usage, reduced charge carrier compounding, and formation of Z-scheme heterojunction with high redox capabilities. The total organic carbon removal reached 95 % while CNAT showed high convincing stability even after four cycles. Given the above results, the hydrothermally prepared composite catalyst can be extended to other organic pollutants such as pharmaceuticals, pesticides, and reduction of inorganics.

Green Solvent γ-Valerolactone (GVL) Facilitates Photocatalytic C-H Bond Activation.

Solvents can significantly influence chemical reactions in condensed phases. Their critical properties are increasingly recognized in various research domains such as organic synthesis and biomass valorization. However, in semiconductor photocatalysis, solvents are primarily viewed as mediums for dissolving and diffusing substances, with their potential beneficial effects on photocatalytic conversions often overlooked. Additionally, common photocatalysis solvents like acetonitrile (ACN) pose serious safety and environmental concerns. In this study, we demonstrate that novel and safe green solvents, such as γ-valerolactone (GVL), can significantly enhance the performance of semiconductor photocatalysis for C-H bond activation. Non-specific solvent-solute interactions are the primary contributors to increased photocatalytic activity in the self-coupling of benzylic compounds. Specifically, GVL's large dielectric constant and high refractive index lower the energy barrier for the rate-determining C-H bond activation step, facilitating a faster coupling reaction. The versatility of GVL is further demonstrated in reactions with multiple reagents and in various oxidation and reduction photocatalytic systems beyond classic C-H bond activation. This work not only pioneers the use of green solvents but also provides comprehensive insights for proper solvent selection in semiconductor photocatalysis.

Green Solvent γ‐Valerolactone (GVL) Facilitates Photocatalytic C−H Bond Activation

AbstractSolvents can significantly influence chemical reactions in condensed phases. Their critical properties are increasingly recognized in various research domains such as organic synthesis and biomass valorization. However, in semiconductor photocatalysis, solvents are primarily viewed as mediums for dissolving and diffusing substances, with their potential beneficial effects on photocatalytic conversions often overlooked. Additionally, common photocatalysis solvents like acetonitrile (ACN) pose serious safety and environmental concerns. In this study, we demonstrate that novel and safe green solvents, such as γ‐valerolactone (GVL), can significantly enhance the performance of semiconductor photocatalysis for C−H bond activation. Non‐specific solvent‐solute interactions are the primary contributors to increased photocatalytic activity in the self‐coupling of benzylic compounds. Specifically, GVL′s large dielectric constant and high refractive index lower the energy barrier for the rate‐determining C−H bond activation step, facilitating a faster coupling reaction. The versatility of GVL is further demonstrated in reactions with multiple reagents and in various oxidation and reduction photocatalytic systems beyond classic C−H bond activation. This work not only pioneers the use of green solvents but also provides comprehensive insights for proper solvent selection in semiconductor photocatalysis.

Unveiling the Synergistic Role of Ferroelectric Polarization and Z‐Scheme Heterojunction in Bi2Fe4O9/Carbon‐Deficient g‐C3N4 for Enhanced Methylene Blue Degradation Efficiency

ABSTRACTEnhancing the efficiency of charge carrier separation is crucial for improving the performance of photocatalysts, thereby offering more effective solutions to energy and environmental pollution challenges. In this study, a carbon‐deficient ultra‐thin porous g‐C3N4 (Vc‐UPCN) was synthesized and subsequently was integrated with Bi2Fe4O9 (BFO) using a sonochemical self‐assembly technique, a Bi2Fe4O9/Vc‐UPCN (BC) photocatalyst featuring a Z‐scheme heterojunction. The BC catalyst was subjected to corona poling treatment to obtain BCp, which possesses an intrinsic electric field. Compared with pure BFO and Vc‐UPCN, the BC heterojunction exhibited higher photo‐generated electron–hole separation efficiency and photodegradation ability. Upon introduction of corona polarization, the photocatalytic performance of BC was further enhanced. Specifically, BCp‐15 (BFO/BC mass fraction = 15) achieved complete degradation of methylene blue (MB) within 30 min. BCp‐15 demonstrated that its degradation efficiency for MB was 1.28 times higher than that of BC‐15, 1.85 times higher than that of Vc‐UPCN, and impressive 7.69 times higher than that of pure BFO. The coupling effect of the heterojunction and ferroelectric polarization significantly improved the separation efficiency of photo‐generated carriers in BCp. This study is expected to provide a reference for the synergistic application of heterojunction and ferroelectric polarization in traditional semiconductor photocatalysis.

Rational synthesis of highly efficient dual–Z–scheme InVO4/FeVO4/Ex–CQDs–g–C3N4 heterojunction for photo(electro)chemical water splitting and pollutant removal applications

BackgroundThe ever–growing concern for environmental pollution and the need for clean energy sources have driven research toward sustainable technologies. Semiconductor photocatalysis has emerged as a promising approach for both environmental remediation and clean energy generation due to its efficiency and environment–friendly nature. This work focuses on developing a novel photocatalyst capable of addressing two crucial environmental challenges: Cr(VI) removal and water splitting for clean hydrogen production. MethodsThis study presents the development of a dual–Z–scheme heterojunction photo(electro)catalyst based on a combination of metal vanadates (FeVO4 and InVO4) and ultrasound–exfoliated carbon–rich graphitic carbon nitride (Ex–C–g–CN), denoted as IVO/FVO/Ex–C–g–CN. The synthesized nanocomposite was thoroughly characterized using various spectroscopic and microscopic techniques (such as XRD, XPS, UV–DRS, FESEM, EDX, and PL) to understand its material properties and structure. These techniques are crucial for elucidating the relationship between the composition of the material and its photocatalytic performance. Significant findingsThe key innovation of this work lies in the design of the dual–Z–scheme heterojunction within the IVO/FVO/Ex–C–g–CN photo(electro)catalyst. This design fosters efficient separation of photogenerated charges, a critical factor for enhancing photocatalytic activity. The effectiveness of this approach is evident in the achieved removal efficiency of 97.17 % for 100 ppm Cr(VI) within just 60 min of visible light irradiation. This demonstrates the superior ability of the developed photocatalyst to address chromium contamination. Furthermore, the photocatalyst exhibits a remarkable photocurrent of 3.16 mA and a low onset potential of 112 mV for the photoelectrochemical oxygen evolution (OER) reaction. These findings highlight the potential of this material for solar–driven water splitting, a clean and sustainable method for hydrogen production. Additionally, the IVO/FVO/Ex–C–g–CN composite demonstrates excellent recyclability, maintaining high Cr(VI) removal efficiency over multiple cycles, indicating its reusability and cost-effectiveness. Overall, the exceptional photo(electro)catalytic performance of the IVO/FVO/Ex–C–g–CN dual–Z–scheme heterojunction positions it as a promising candidate for tackling environmental pollution and generating clean energy.

Defect States and Polarons in Photocatalytic Semiconductors Revealed via Time-Resolved Spectroscopy

Defect States and Polarons in Photocatalytic Semiconductors Revealed via Time-Resolved Spectroscopy

Zinc/Magnesium Ferrite Nanoparticles Functionalized with Silver for Optimized Photocatalytic Removal of Malachite Green.

Water pollution is a major environmental challenge. Due to the inefficiency of conventional wastewater treatment plants in degrading many organic complex compounds, these recalcitrant pollutants end up in rivers, lakes, oceans and other bodies of water, affecting the environment and human health. Semiconductor photocatalysis is considered an efficient complement to conventional methods, and the use of various nanomaterials for this purpose has been widely explored, with a particular focus on improving their activity under visible light. This work focuses on developing magnetic and photoactive zinc/magnesium mixed ferrites (Zn0.5Mg0.5Fe2O4) by sol-gel and solvothermal synthesis methods, which are two of the most important and efficient methods used for the synthesis of ferrite nanoparticles. The nanoparticles (NPs) synthesized by the sol-gel method exhibited an average size of 14.7 nm, while those synthesized by the solvothermal method had an average size of 17.4 nm. Both types possessed a predominantly cubic structure and demonstrated superparamagnetic behavior, reaching a magnetization saturation value of 60.2 emu g-1. Due to the high recombination rate of electrons/holes, which is an intrinsic feature of ferrites, surface functionalization with silver was carried out to enhance charge separation. The results demonstrated a strong influence of adsorption and of the deposition of silver. Several optimization steps were performed during synthesis, allowing us to create efficient catalysts, as proved by the almost full removal of the dye malachite green attaining 95.0% (at a rate constant of 0.091 min-1) and 87.6% (at a rate constant of 0.017 min-1) using NPs obtained by the sol-gel and solvothermal methods, respectively. Adsorption in the dark accounted for 89.2% of the dye removal for nanoparticles prepared by sol-gel and 82.8% for the ones obtained by the solvothermal method. These results make mixed zinc/magnesium ferrites highly promising for potential industrial application in effluent photoremediation using visible light.

Investigation of La-BiVO4/g-C3N4 photocatalytic system for efficient removal of hazardous water contaminants

The application of semiconductor photocatalysis powered by renewable energy sources for environmental remediation of emerging contaminants has gained significant research interest in recent years. Lanthanum-substituted bismuth vanadate (La-BiVO4)/graphitic carbon nitride (g-C3N4) heterojunctions were synthesized for the photocatalytic degradation of emerging water contaminants. Significantly, La³+ substitution serves as a model system for exploring the broader concept of cationic substitutions on BiVO4. By strategically replacing a portion of Bi(III) with various cations, we can potentially tailor the electronic structure of BiVO4 for enhanced photocatalytic performance. Photoelectrochemical analysis confirmed rapid charge separation and reduced resistance, leading to effective contaminant degradation. The La-BiVO4/g-C3N4 nanocomposite exhibited exceptional photocatalytic performance under simulated solar light irradiation (Xe-350W, AM 1.5 G), achieving 87.66% photooxidation of roxarsone within 150 min, surpassing g-C3N4, BiVO4, LaVO4, La-BiVO4, BiVO4/g-C3N4, and LaVO4/g-C3N4 by factors of 1.94, 1.26, 2.25, 1.39, 1.13, and 2.51, respectively. Moreover, it demonstrated 99.61% degradation of Cr(VI) after 60 min, outperforming g-C3N4, BiVO4, LaVO4, La-BiVO4, BiVO4/g-C3N4, and LaVO4/g-C3N4 by factors of 1.11, 1.81, 1.62, 1.67, 1.20, and 1.13, respectively. These findings underscore the superior photocatalytic efficacy of the La-BiVO4/g-C3N4 nanocomposite. The efficient photocatalytic activity of La-BiVO4/g-C3N4 type-II heterojunctions demonstrates its potential for real-world environmental remediation. This material offers a promising strategy for removing harmful water contaminants, thereby mitigating risks associated with water consumption.

Preparation of MoS2/CdS/TNAs ternary composite structures and study of their photocatalytic properties

TiO2 has long been favored by researchers as a representative of semiconductor photocatalysts. Titanium dioxide nanotubes (TNAs) have a larger specific surface area, which makes them more valuable for the design of photocatalyst carriers. CdS is also a typical photocatalytic semiconductor material with a narrow bandwidth, which has a better performance in the visible light region. However, it also has certain problems such as photocorrosion. The composite MoS2 has a better inhibition effect. In this study, MoS2 and CdS were composited on TNAs using electrochemical deposition for the first time, and MoS2/CdS/TNAs (MCT) ternary composite nanostructures were successfully prepared. The effects of electrochemical deposition voltage, reaction time, and the ratios of molybdenum and sulfur sources in the electrolyte on the MCT composite structures were investigated. In this work, the photocatalytic degradation of organic water pollutants was simulated using methylene blue, and the degradation rate reached 93.1% at 150 min. After cycling the degradation experiments for five times, the photocatalysts still had good stability. The results showed that the MCT has good photocatalytic activity, which provides a feasible way for TNAs in the design of photocatalyst carriers.

Rhodamine B degradation over visible light promoted Bi2WO6/Bi2W0.75Mo0.25O6 and Bi2MoO6/Bi2W0.75Mo0.25O6 heterostructures: DFT and photocatalytic studies

In the recent past, the dye degradation through semiconductor photocatalysis under visible light has drawn the widespread attention. In this view, visible active (1-x)Bi2WO6/xBi2W0.75Mo0.25O6 and (1-x)Bi2MoO6/xBi2W0.75Mo0.25O6 (commonly 0.05 ≤ x ≤ 0.20 wt%) heterostructures prepared through a one-step hydrothermal process. These compounds were analyzed by XRD, FE-SEM, HRTEM, XPS, FT-IR, DFT, UV-Vis DRS and photoluminescence. In (1-x)Bi2WO6/xBi2W0.75Mo0.25O6, the 0.90Bi2WO6/0.10Bi2W0.75Mo0.25O6 heterostructure showed the highest photocatalytic activity in comparison with Bi2WO6 and Bi2W0.75Mo0.25O6. On contrary, all (1-x)Bi2MoO6/xBi2W0.75Mo0.25O6 heterostructures exhibited the less photocatalytic activity than that of Bi2MoO6. The analysis carried out on both heterostructures clearly demonstrated that (1-x)Bi2WO6/xBi2W0.75Mo0.25O6 is more active in comparison to (1-x)Bi2MoO6/xBi2W0.75Mo0.25O6. The radical trapping test was conducted for 0.90Bi2WO6/ 0.10Bi2W0.75Mo0.25O6 heterostructure, asserted that O2∙− and h+radicals were dominant species responsible for Rhodamine B (Rh B) photo-degradation. The estimated redox potentials of Bi2WO6, Bi2W0.75Mo0.25O6 establish the fact that the charge (e-/h+) migration between Bi2WO6 and Bi2W0.75Mo0.25O6 via Z scheme is accountable for the aggressive photocatalytic activity of Bi2WO6/Bi2W0.75Mo0.25O6 heterostructure. The plausible Z scheme mechanism of the generation of electron-hole pairs, charge transfer and also visible light-induced degradation of Rh B was proposed.