Surface Of Bi2WO6 Research Articles

Bi2WO6 and TiS2 composite nanostructures displaying synergetic boosted energy storage in supercapacitor

The enhancement in the capacitance of a supercapacitor has been successfully achieved by synthesizing Bi2WO6 (BW), TiS2 (T), and Bi2WO6/TiS2 (BW/T) composites utilizing the hydrothermal process. The possible growth mechanism has also been presented. The morphological and structural characteristics of the cultivated samples were observed using FT-IR, XRD, SEM, EDS, and UV–vis spectroscopy techniques. TiS2 nano platelets uniformly dispersed across the hierarchically opened surface of Bi2WO6 in the synthesized hierarchical composite. This leads to an increase in surface porosity and surface area, which in turn enhances the transport of electrons and ions on the composite BW/T surface. The optimal electrode BW/T@40 % composite electrode shown a substantial enhancement in particular capacitance (1153.3 F/g) compared to the separate BW (523.7 F/g) and T (453.3 F/g) electrodes due to its rapid ion transfer, many active sites on its large surface area, and strong synergistic impact. Furthermore, the BW/T@40 % combination demonstrated exceptional stability, with over 92 % of its capacitance maintained after 4500th cycles and b value (0.71) proved the supercapacitor behavior. Therefore, BW/T@40 % binary metal oxide and sulfide composites exhibit improved specific capacitance and greatly prolonged life-cycle, confirming its potential use in high-performance energy storage devices.

Rare earth induced lattice distortion of Bi2WO6 to effectively improve photocatalytic performance: Experimental and DFT calculations

The excellent visible light photocatalytic activity of bismuth-based photocatalysts has attracted the interest of many scholars at home and abroad. In this paper, rare earth (Sm, La, Ce, Eu) doped Bi2WO6 photocatalysts were prepared by a one-step hydrothermal method using bismuth nitrate and sodium tungstate as precursors. The microstructures and spectroscopic performances of prepared materials were investigated utilizing characterization methods, such as XRD, XPS, UV–vis, TEM, and N2 adsorption-desorption, etc., and the effluent removal performances were studied by using rhodamine B as a simulated degradation dye and the photodegradation mechanism was investigated in combination with DFT calculations. XRD indicates that the rare earth doping leads to the lattice distortion of the (131) crystal surface of Bi2WO6, and the relative amount of distortion is directly proportional to the photocatalytic activity; UV–vis spectra show that the absorption edge of Bi2WO6 is obviously red-shifted with the rare earth doping, and N2 adsorption-desorption curve show that the doped rare earths make the specific surface area of the sample effectively increased. Moreover, XPS spectrum suggests that the doped rare earth Ce and Eu often exist in the form of metastable oxidation states, and the transformation between Ce3+/Ce4+ and Eu2+/Eu3+ oxidation states is easy to form impurity energy levels between Bi2WO6, which make the energy level significantly enriched to broaden the absorption range and reduce band gap width of the material. DFT calculations further indicate that the rare earths successfully replace Bi sites. One of the main reasons for the improvement of photocatalytic activity is that rare earth doping is easier to replace Bi sites, leading to increased relative aberration; another one is that the arrangement of EVB and ECB in the photocatalytic mechanism is type-II, which contributes to red-shift of absorption edge and effective separation of electron-hole pairs in the photocatalytic process, thus improving the photocatalytic activity.

A novel bio-photocatalytic system for efficient degradation of indole by Bi2WO6-Ni-DA@HRP photoperoxidase microspheres

The photoperoxidase microspheres Bi2WO6-Ni-DA@HRP were prepared by covalent binding under the action of electrostatic adsorption for the first time. It was achieved that horseradish peroxidase (HRP) was immobilized on the Bi2WO6via the self-polymerization of dopamine (DA). In this bio-photocatalytic system, the free radicals produced in situ on the surface of Bi2WO6 can activate HRP and induce the photo-enzyme synergistic catalysis function. The interfacial binding force between HRP and the photocatalyst significantly enhanced the electron conduction effect, which improved the separation efficiency and mobility of photogenerated electron-holes, and thus the catalytic effect was improved successfully. Compared with Bi2WO6 and free HRP, Bi2WO6-Ni-DA@HRP under no-added H2O2 have exhibited excellent catalytic activity for indole. The degradation efficiency reached 99.9 % for 20 mg·L−1 indole solution treated with Bi2WO6-Ni-DA@HRP for 210 min under visible light initiation. The free radical trapping experiment showed that holes (h+) and ·OH were the main active substances in the catalytic process. The photoperoxidase catalyst constructed in this study proposed a novel practical approach for the degradation of indole in water and significantly improved the application of HRP in water treatment.

An all-in-one self-supporting Na-Bi2WO6 photocatalyst for portable air purifier: Laminar splitting boosts high efficacy in mineralizing toluene and disinfection

An air purifier that provides clean air will be popular if it is portable and capable of removing volatile organic chemicals and reducing exposure to bacteria. Herein, ultra-thin and dense Bi2WO6 nanoflakes grown on W meshes specialize in offering abundant oxygen vacancies due to Na+ driving laminar splitting. Under visible lights, the photogenerated carriers streaming along the ultrathin Bi2WO6 surface produce bountiful reactive oxygen species for mineralizing VOCs and sweeping bacteria. Enriched with •O2- and •OH, a 15 cm*5 cm Na-Bi2WO6 mesh can completely degrade 30 ppm toluene in 0.45 dm3 reactor in 1 hour without producing any toxic intermediates like benzene, and its efficacy only decayed by 4% after a continuous 14-hour run. A cup-shaped air purifier was assembled with the Na-Bi2WO6 mesh, enabling the rapid elimination of 1 ppm toluene, 2 ppm formaldehyde, and bacteria within a 120 dm3 test space.

Dual catalytic system: Cu2O@Bi2WO6 2D nano-chips nanocomposite for CO2 photoreduction with amine promotion towards sustainable energy and chemicals

The pursuit of sustainable energy and chemical synthesis propels the development of advanced catalytic systems in photocatalytic CO2 conversion and pharmaceutical chemicals production. The present study demonstrated the decorated Cu2O nanoparticles on a Bi2WO6 surface with effective contact that improved the optical properties of the nanocomposite photocatalyst. The nanocomposite was synthesized via hydrothermal method and achieved ∼7 nm nanoparticle size of Cu2O with a high surface area, refers many active sites at the photocatalyst surface. The photocatalyst efficiently reduced CO2 into CO (2315 μmol-g−1) and CH4 (965 μmol-g−1) under visible light irradiation; simultaneously, the coupling of amines produced chemicals necessary for the pharmaceuticals. In addition, the amine behaves like a sacrificial electron donor in the process; thus, it makes the photocatalytic system prominent in energy conversion.

3D WO3/BiMOF/Bi2WO6 with rich vacancies defects self-assembled via H2BDC anchoring Bi source of Bi2WO6 for high-performance visible light-driven nitrogen fixation and organic pollutant degradation

A novel photocatalyst WO3/BiMOF/Bi2WO6 was prepared by self-assembly of benzene dicarboxylic acid ligand (H2BDC) anchoring Bi source on the surface of Bi2WO6 to form BiMOF, in which WO3 spherical particles were scattered uniformly. Thereby, an amount of metal and oxygen vacancies (VM + O) are generated. The 3D flower-like spherical photocatalyst has a large specific surface area and close interfacial contacts, which can provide sufficient channels for carrier migration. The introduction of BiMOF enhanced the light absorption capability of photocatalyst. As a result, the flower-like WO3/BiMOF/Bi2WO6 structure exhibits excellent nitrogen fixation as well as high-level photocatalytic activity in degrading Rhodamine B (RhB) and tetracycline (TC) under visible light. For one thing, WO3/BiMOF/Bi2WO6 produce ammonia up to 227 μmol L−1 h−1. For another, the degradation efficacy displayed by RhB 99.3% in 15 min and TC 93.6% degradation in 50 min, respectively. In addition, the catalysts showed excellent cyclic stability, with constant degradation efficiencies for at least 4 cycles. The experimental results of free radical scavenging showed that holes (h+) and superoxide radical (·O2−) were the main active substances in the photodegradation process. Therefore, the photocatalytic mechanism of 3D flower-like WO3/BiMOF/Bi2WO6 was also proposed.

Plasma treatment enhanced piezo-photocatalytic performance of Bi2WO6 for efficient degradation of tetracycline hydrochloride

Photocatalysis is limited by the high recombination rate of photogenerated e- and h+, but the piezoelectric effect can enhance the separation efficiency of charge carriers, so that the combining piezoelectric catalysis with photocatalysis is a highly promising approach for improving catalytic performance. In this study, aim to enhance piezo-photocatalytic performance, plasma treatment was applied to modify the surface of Bi2WO6 to form oxygen vacancies. After plasma treatment, Bi2WO6 exhibited a larger specific surface area, thinner thickness, narrower band gap, etc. These improvements have been confirmed to enhance the piezoelectric response of Bi2WO6, facilitate band bending and further improve the absorption of visible light, accelerate the separation of charge carriers, thus enhanced the piezo-photocatalytic activity. Consequently, utilization of plasma treatment had improved greatly the piezo-photocatalytic performance of Bi2WO6 for the degradation of tetracycline hydrochloride. Impressively, plasma treatment promoted the generation of 1O2 during the piezo-photocatalytic reaction, emphasizing the advantages of utilizing plasma treatment for improving the performance of piezo-photocatalysts. This work highlights the use of plasma treatment to increase active sites and induce vacancy defects on the surface of catalysts, which exhibit excellent piezo-photocatalytic degradation performance and show great potential in the field of environmental remediation.

In-situ Construction of Oxygen Vacancies-Rich Direct Z-Scheme δ-Bi2O3/Bi2WO6 Heterojunction for Enhanced Photocatalytic N2 Fixation

The recombination of interface charges hindered photocatalytic nitrogen fixation (NRR), but the introduction of surface oxygen defects (OV) and the construction of heterojunctions were found to effectively separate charges at the interface and enhance NRR efficiency. Here we successfully constructed the δ-Bi2O3/Bi2WO6 (BBWO-3) heterojunction with a core-shell similar structures and OV-rich via a solvothermal method, where the δ-Bi2O3 nanosheets were grown in-situ on the surface of Bi2WO6 (BWO) hollow microspheres. The optimized BBWO-3 achieved a nitrogen fixation yield of 65.6 μmol-1·g-1Cat under simulated sunlight, which was 6 times that of δ-Bi2O3 and 2.8 times that of Bi2WO6, without needing sacrificial agents. The enhanced photocatalysis activity was attributed to OV and the formation of direct Z-Scheme heterojunction with core-shell similar structures, achieving effective spatial separation of photogenerated charges and providing a dedicated pathway for charge migration. At the meanwhile, since the bending of the band, an internal electric field (IEF) was formed from δ-Bi2O3 to BWO at the interface, which accelerate the dynamics of charge transfer. Moreover, the mechanism of the NRR was elucidated based on density functional theory (DFT) and in-situ XPS. This study provides a new idea for the construction of OV-rich core-shell similar structures direct Z-Scheme heterojunction photocatalysts.

Rapid and efficient visible-light-actuated green photocatalytic synthesis of aniline from toxic nitrobenzene through novel mesoporous AgVO3/Bi2WO6 nanosheets

Heterogeneous photocatalysis, a "green" approach, could convert numerous noxious materials (such as nitrobenzene) into valuable compounds (such as aniline). Unfortunately, the inadequate efficiency of photoinduced charge carriers' segregation, ineffectual light harvesting efficiency, and the poor stability of the photocatalyst in the solution are significant challenges for photocatalytic applications. In this report, for the first time, two-dimensional (2D) mesoporous AgVO3/Bi2WO6 heterojunctions were fabricated through a facile surfactant assisted-hydrothermal route, followed by impregnation and calcination, using different AgVO3 contents (4–16 wt%), to be applied for phototransformation of nitrobenzene into aniline under visible illumination. Physicochemical characterization revealed that the nanosheet configuration and porous nature of Bi2WO6 did not alter after loading AgVO3. However, the AgVO3 loading greatly affected the Bi2WO6 catalyst's textural, absorption, and energy bandgap. Notably, only 12 wt% AgVO3 on the Bi2WO6 surface led to dropping the specific surface area from 140 to 125 m2 g−1, improving the absorption edge from 452.06 to 536.05 nm, and reducing the band gap from 2.74 to 2.23 eV. Just 2.4 g L−1 of the optimum AgVO3/Bi2WO6 photocatalyst (12 wt% AgVO3) displayed a complete photoreduction for nitrobenzene to aniline within only 40 min with outstanding reusability and recyclability. The AgVO3 significantly improved photoinduced charge carriers' separation and migration through a step (S)-scheme heterojunction with Bi2WO6. This study opens the door to developing the green conversion of wastes into value-added compounds through heterogeneous photocatalysis.

Bi2WO6@g-C3N4 Heterostructure for Cathodic Photoelectrochemical Dopamine Sensor

A simple and low-cost cathodic photoelectrochemical (PEC) sensor based on Bi2WO6@g-C3N4 was designed for dopamine (DA) detection. The Bi2WO6 nanoflower was first prepared using a simple hydrothermal method followed by the combination with g-C3N4 nanosheet to form the Bi2WO6@g-C3N4 heterostructure. The heterostructure can extend the absorbance to the visible region and accelerate the transfer of charge carriers. Furthermore, DA easily coordinates with exposed Bi3+ on the Bi2WO6 surface and forms the charge-transfer complex to further enhance the cathodic photocurrent. Under optimal conditions, there are two linear relationships between the concentration of DA and photocurrent intensity. The linear ranges are 0.1–10 µM and 10–250 µM, with a sensitive detection limit (LOD) of 28 nM. Notably, the real sample of human blood serum analysis further revealed the accuracy and feasibility of the Bi2WO6@g-C3N4-based PEC platform. Convincingly, the heterostructure of Bi2WO6 and g-C3N4 opened up a new avenue for the construction of DA analysis.

Synthesis of Z-type spherical B-g-C3N4/Bi2WO6 heterojunctions for enhanced rhodamine B degradation

A spherical B-g-C3N4/Bi2WO6 heterojunction photocatalyst was synthesized using the hydrothermal coprecipitation method. Scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and ultraviolet–visible diffuse reflectance spectroscopy (DRS) showed that B-g-C3N4 was uniformly dispersed on the Bi2WO6 surface through a strong chemical bond, reducing the energy bandgap of Bi2WO6. The outcomes of the experiment regarding the photocatalytic degradation of rhodamine B (RhB) demonstrated a notable enhancement in the degradation rate for the 1:3 BCN/BWO composite. Specifically, the degradation rate was found to be 76 times greater than that of B-g-C3N4 and 7 times higher than that of Bi2WO6. Furthermore, a photocatalytic degradation mechanism was proposed based on the results of ultraviolet photoelectron spectroscopy (UPS) and free radical capture experiments. The direct Z-type B-g-C3N4/Bi2WO6 heterojunction structure promotes the effective separation of photogenerated carriers and enhances their oxidation-reduction ability.

Construction of Z-scheme Ag/AgCl/Bi2WO6 photocatalysts with enhanced visible-light photocatalytic performance for gaseous toluene degradation

As a typical aromatic volatile organic compounds (VOCs), toluene is difficult to be decomposed by photocatalysts under visible-light driven. Herein, the Ag/AgCl/Bi2WO6 heterojunction photocatalysts were synthesized by multi-step process involving chemical deposition of AgCl on the surface of Bi2WO6 and subsequently photoreduction of Ag0 nanoparticles by UV light. The as-synthesized photocatalysts were characterized by XRD, SEM, TEM, XPS, UV–vis, PL and ESR to investigate the microstructures and electronic structures. The corresponding degradation efficiencies of gaseous toluene were evaluated and the optimal Ag/AgCl/Bi2WO6 exhibited almost 99.9% removal rate after 60 min illumination with visible light (>420 nm). The optical absorption properties and radical trapping experiments revealed the possible energy band structure of Ag/AgCl/Bi2WO6 heterojunction. Finally, the possible enhancement mechanism was also proposed that the cooperation of surface plasmon resonance (SPR) effect, efficient separation of electron-hole pairs, extension of the carrier lifetime as well as the high redox potentials of Z-scheme heterojunction were the primary reasons. Therefore, construction of Z-scheme heterojunction of Ag/AgCl/Bi2WO6 with higher redox ability is an effective way to degradation gaseous toluene under visible-light irradiation.

Photoelectrochemical reforming of glycerol by Bi2WO6 photoanodes: Role of the electrolyte pH on the H2 evolution efficiency and product selectivity

Photoreforming of biomass derivatives is a promising strategy for the production of green hydrogen and chemicals. Herein, nanocrystalline Bi2WO6 photoanodes were applied for the first time for the conversion of glycerol in different pHs. Different from TiO2 photoanodes, the photocurrent for Bi2WO6 films is relatively independent of the applied potential, which is attributed to the preferential glycerol oxidation in detriment of water oxidation. Impedance measurements reveal that photocurrent is limited by the charge transfer on the Bi2WO6 surface and is partially inhibited by the poor desorption of glycerol oxidation products. At pH 6, photocurrents up to 0.69 mA cm−2 are reached with a faradaic efficiency for H2 evolution of 100% and 41% selectivity for formate production. In acid media, this selectivity increases to 88%, but the photocurrent decreases 50%. In alkaline media, glycerol oxidation is facilitated and photocurrents up to 0.80 mA cm−2 are reached at the cost of poor product selectivity.

Metal-induced oxygen vacancies on Bi2WO6 for efficient CO2 photoreduction

Semiconductor-based photocatalysis for efficient solar energy conversion is an ideal strategy to tackle the growing global energy and environmental crisis. However, the development of photocatalysis is still limited by problems such as low utilization of visible light, low efficiency of charge transfer and separation, and insufficient reactive sites. Herein, Au nanoparticles (NPs) were deposited on the surface of Bi2WO6 by a one-step reduction method, which simultaneously induced the formation of oxygen vacancies (OVs) on the surface of Bi2WO6. The OVs concentration is found to be increased with the increase of Au loading. Au NPs and OVs improve the light absorption and facilitate the separation and transport of the photogenerated carriers. In addition, OVs act synergistically with the nearby metal active sites to optimize the adsorption energy of reactants on the catalyst surface, changing the adsorption form of CO2 molecules on the catalyst surface. The as-synthesized photocatalyst achieved a photocatalytic performance of up to 34.8 µmol g−1 h−1 of CO2 reduction to CO without sacrificial agent in a gas-solid system, which is 9.4 times higher than that of the pristine Bi2WO6. This work may further deepen our understanding on the relationship between metal NPs and OVs, and their combined role in photocatalysis.

Synthesis of Sn doped-Bi2WO6 nanoslices for enhanced isopropanol sensing properties

Bi2WO6 has sparked a lot of attention as a gas sensor in recent years. However, in most cases, the working temperature is quite high. The Sn doped- Bi2WO6 slice-shaped nanostructure material was generated using a cost-effective one-step hydrothermal process in this study. The material was evaluated using X-ray diffraction (XRD), field emission scanning microscope (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) and an energy-dispersive X-ray detector (EDX). The results show that the 5 wt% Sn doped- Bi2WO6 sensor has outstanding isopropanol gas sensitivity. The sensor's optimal operating temperature is 260 °C, and it responds to low isopropanol concentrations. The unique interfacial interaction between 2D slice-shaped nanostructures and Sn doping, which provides additional catalytic active sites on the Bi2WO6 surface and improves electrical responsiveness and gas sensitivity, is responsible for the improved gas sensitivity.

Tin bisulfide nanoplates anchored onto flower-like bismuth tungstate nanosheets for enhancement in the photocatalytic degradation of organic pollutant

The development of efficient heterojunctions through a simple and facile method is an effective way to enhance the photocatalytic performance of bismuth-based oxide semiconductors for industrial applications. Here, the novel flower-like type II SnS2/Bi2WO6 heterostructure consisting of bismuth tungstate (Bi2WO6) nanosheets and tin bisulfide (SnS2) nanoplates was successfully designed and synthesized. The crystal structure, composition, morphology, and photoelectric properties of the heterostructure were systematically characterized. In addition, the photocatalytic activity of SnS2/Bi2WO6 was analyzed and compared with Bi2WO6 or SnS2 alone or physical mixture of SnS2 and Bi2WO6. 2%SnS2/Bi2WO6 presents a 3.1 times greater degradation rate constant (0.0065 min–1) than that of Bi2WO6 (0.0021 min–1) under low visible light irradiation (5.3 mW·cm–2, a 44 W LED), while SnS2 alone exhibits no photocatalytic effect toward glyphosate. Furthermore, 2%SnS2/Bi2WO6 maintains 93% of its original photocatalytic activity even after four cycles. The possible photocatalytic degradation pathway of glyphosate and photocatalytic mechanism are also proposed. The excellent photocatalytic performance of SnS2/Bi2WO6 is attributed to the decoration of SnS2 nanoplates on the surface of Bi2WO6, appropriate (113)/(020) ratio, increased visible-light absorption, and effective separation of photoinduced carriers. This paper reports a new methodology that can act as a reference basis to design and develop visible-light responsive photocatalysts with outstanding photocatalytic performance for carbon dioxide reduction, water splitting, and pollutant degradation.

Bi0 and oxygen vacancies co-induced enhanced visible-light photocatalytic detoxication of three typical contaminants over Bi2WO6 treated by NaBH4 solution

In this work, the photocatalytic performance of bismuth tungstate (Bi2WO6) was notably improved through the synergism of oxygen vacancies (OVs) and surface plasmon resonance (SPR) effect of Bi0. After treated with NaBH4 solution, the content of OVs and Bi0 on the surface of Bi2WO6 can be regulated. The effects of the NaBH4 solution treatment on visible-light photocatalytic performance of Bi2WO6-based photocatalysts on the degradation of rhodamine B (RhB), tetracycline (TC) and phenol (PhOH) were indagated. The highest photocatalytic performance was obtained for BWO-100. The degradation reaction rate constant of RhB, TC and PhOH on BWO-100 is 2.3, 1.65 and 2.1 times of that over the fresh Bi2WO6, respectively. Introduction of richer OVs and relative lower content of metal Bi0 endows Bi2WO6 with highly efficient separation of photogenerated carriers, which leads to increased superoxide radicals (•O2−), hydroxyl radicals (•OH), and the experimental results have proven that they are the main active substances that mineralize above three typical organic pollutants. This demonstration provides a reference for design highly efficient photocatalysts by a mild strategy.

Preparation and photocatalytic performance of CdS@Bi2WO6 hybrid nanocrystals

The hybrid nanocrystals of cadmium sulfide (CdS) and bismuth tungstate (Bi2WO6) (CdS@Bi2WO6) were well-prepared in the nanoreactors of Bi2WO6-contained sodium polyacrylate (PAANa) latex particles, by means of cadmium sulfate/sodium sulfide (CdSO4/Na2S) solutions absorption and solvothermal treatment. The influences of CdSO4/Na2S millimolar ratio on structure and photocatalytic performance of hybrid nanocrystals were investigated. With 3:1 of Cd2+/S2- millimolar ratio in feeding, CdS nanorods on the surface of Bi2WO6 cluster were obtained and its length increased after solvothermal treating; the resultant CdS@Bi2WO6 degraded 96.1% of RhB after illuminating for 120 min, which was more effective than others. With the 1:2 or 1:3 of Cd2+/S2- millimolar ratio, the solvothermal treated cubic-CdS were agglomerated to cluster which attached on the surface of Bi2WO6 cluster, and the agglomerates size increased accordingly. The photocatalytic mechanism suggests that the superoxide ions and holes were the active species produced by CdS@Bi2WO6 in the photocatalytic process. The grown CdS nanorods on the surface of Bi2WO6 had better charge separation ability than the grown CdS clusters on the surface of Bi2WO6. The CdS@Bi2WO6 hybrid nanocrystal with the definite-designed structure will possess the excellent photocatalytic performance.

Constructing Surface Plasmon Resonance on Bi2WO6 to Boost High-Selective CO2 Reduction for Methane.

Plasmonic Bi2WO6 with strong localized surface plasmon resonance (LSPR) around the 500-1400 region is successfully constructed by electron doping. Oxygen vacancies on W-O-W (V1) and Bi-O-Bi (V2) sites are precisely controlled to obtain Bi2WO6-V1 with LSPR and Bi2WO6-V2 with defect absorption. Density functional theory (DFT) calculation demonstrates that the V1-induced energy state facilitates photoelectron collection for a long lifetime, resulting in LSPR of Bi2WO6. Photoelectron trapping on V1 sites is demonstrated by a single-particle photoluminescence (PL) study, and 93% PL quenching efficiency is observed. With strong LSPR, plasmonic Bi2WO6-V1 exhibits highly selective methane generation with a rate of 9.95 μmol g-1 h-1 during the CO2 reduction reaction (CO2-RR), which is 26-fold higher than 0.37 μmol g-1 h-1 of BiWO3-V2 under UV-visible light irradiation. LSPR-dependent methane generation is confirmed by various photocatalytic results of plasmonic Bi2WO6 with tunable LSPR and different light excitations. Furthermore, the DFT-simulated pathway of CO2-RR and in situ Fourier transform infrared spectra on the surface of Bi2WO6 prove that V1 sites facilitate CH4 generation. Our work provides a strategy to obtain nonmetallic plasmonic materials by electron doping.

Thermodynamic stability and electronic structure properties of the Bi2WO6 (0 0 1) surface: First principle calculation

In this work, using a density functional theory (DFT)-based thermodynamic approach, we studied the stability of possible termination structures for the (001) surface of Bi2WO6. The Bi-W-O surface phase diagrams of the various surface terminations are constructed by obtained surface Gibbs free energies. We find that the five terminations of Bi2WO6 (001) surface can be stabilized under certain thermodynamic equilibrium conditions, though their stability is different significantly. Moreover, based on a hybrid functional, we calculate the five categories of surface termination's surface electronic structures. It is found that there are fat bands of the surface states in OW termination, which can contribute to visible light absorption. Therefore, an enhanced optical absorption in the visible light region is predicted in the OW termination. Furthermore, work functions are remarkably distinct for various surface terminations. This suggests that the direct Z-scheme heterostructure of Bi2WO6-based can be controlled by obtaining the thermodynamically preferred surface termination under suitable conditions. These results may help explore intrinsic properties for Bi2WO6 surfaces, providing a useful strategy for experimental studies of Bi2WO6-based photocatalyst in the future.