Surface Of BiVO4 Research Articles

Laser-generated BiVO4 colloidal particles with tailoring size and native oxygen defect for highly efficient gas sensing

To alleviate the poor sensing performance of BiVO4, developing new strategies for the fabrication of unique device with improved sensing properties is very necessary and has great practical significance. In this work, size-tailored and uniform black BiVO4 colloids with abundant oxygen vacancy were synthesized by a unique method of pulsed laser irradiation of colloidal nanoparticles (PLICN). The corresponding laser irradiation effects on the sensing properties are comparatively investigated. The results indicate that the BiVO4 nanospheres with average size of 50 nm shows best sensing properties with high sensitivity, superior selectivity, low detection limit (44 ppb) to H2S at low working temperature (75 °C). Its sensing response is over 4 times higher when comparing with that of the raw material. Further investigation manifests that laser irradiation could induce quantity of the oxygen vacancy and decrease the resistance of the sensing device, which is mainly responsible for the enhanced sensing performance. Moreover, the density functional theories (DFT) calculations suggest that the oxygen vacancies can greatly decrease the surface absorption energy with enhanced H2S absorption capability on BiVO4 surface and lower the bader charger transfer from the absorbed H2S molecules to the BiVO4, thus enabling the implementation for the enhanced gas-sensing properties.

Utilization of Bi2WO6-encapsulated polyaniline-based redox reactions for the efficient detoxification of organic pollutants

Water contamination by toxic organic pollutants remains a serious public health problem for humans due to their long-lasting effects, so attention on specific methods and technologies to remove organic pollutants from waste water is desired. Numerous methods and photocatalysts are reported for the degradation of organic pollutants. In this work, BiVO4/Bi2WO6@polyaniline nanostructures were prepared successfully through facile wet chemical co-precipitation method and in sequence deposited over the BiVO4 surface for the first time. The surface morphology of synthesized photocatalysts was observed by scanning electron microscopy (SEM) and structural properties were investigated by X-ray diffraction (XRD). The addition of polyaniline and Bi2WO6 into BiVO4 shifted the characteristic peaks of BiVO4 towards lower 2θ angle which is clear evidence of doping of these elements into BiVO4 structure under these conditions. In addition, the crystallite size of BiVO4 was also decreased due to incorporation of doping elements. Compared with pure BiVO4, hybrid photocatalysts exhibit higher photocatalytic activity and stability for degradation of phenol and ciprofloxacin under visible-light irradiation. When the effect of PANI in BiVO4–Bi2WO6 was examined, 1% PANI/BiVO4–Bi2WO6 heterojunction exhibited the highest photocatalytic performance. The degradation efficiency for phenol was 98% and 99% for ciprofloxacin at 90 min and this value was about seven times and three times higher than as compared to pure BiVO4 and BiVO4–Bi2WO6, respectively. The obviously improved photocatalytic performance of BiVO4–Bi2WO6/PANI composite was mainly ascribed to unique hierarchical structures, harvesting extended region of visible light, higher surface area, higher crystallinity, electronic transmission and narrow band gap, which significantly enriched the adsorption capacity and accordingly facilitated the separation of photogenerated charge carriers. The current findings may provide new insights into the employment of hybrid photocatalysts and improving the photocatalytic activity to address energy and environmental issues.

Immobilization of Metal-Organic Framework MIL-100(Fe) on the Surface of BiVO4: A New Platform for Enhanced Visible-Light-Driven Water Oxidation.

The development of new dual functional photocatalysts is highly desirable for conversion and storage of solar energy. Herein, we first constructed hierarchical structure MIL-100(Fe)@BiVO4 in situ growing MIL-100(Fe) nanoparticles (NPs) on the surface of decahedron BiVO4 under mild hydrothermal conditions. The as-synthesized hybrid nanostructure is unambiguously determined using a series of characterization methods. These results demonstrate that the ultra-tiny MOF MIL-100(Fe) particles are immobilized on the surface of decahedron BiVO4 and the composite exhibits a strong interaction between BiVO4 and MIL-100(Fe). This hybrid material MIL-100(Fe)@BiVO4 is employed as a photocatalyst for water oxidation reaction and demonstrates higher O2 production activity in comparison with bare BiVO4. The best performance obtained at the optimal mass percentage of MIL-100(Fe) (8.0 wt %) reaches 333.3 μmol h-1 g-1 of the O2 evolution rate irradiated with visible light, which is almost 4.3 times higher than bare BiVO4 (77.3 μmol h-1 g-1). The enhanced water oxidation performance is due to the more efficient interfacial electron-hole transfer between MIL-100(Fe) and BiVO4, which is verified by the results of various photo-electrochemical characterizations. Moreover, the as-prepared composite MIL-100(Fe)@BiVO4 also displays excellent stability for visible-light-driven water oxidation. This study affords a rational strategy for the controllable construction by loading metal-organic frameworks on a semiconductor surface, which is a good reference for other artificial photosystems.

In situ modification of BiVO4 nanosheets on graphene for boosting photocatalytic water oxidation.

Owing to the sluggish water oxidation process, unearthing an ideal model for disclosing the impact of an architectural approach on the water oxidation activity of photocatalysts becomes a vital issue. Here, we propose an innovative in situ modification strategy for constructing ultrapure BiVO4 nanosheets on graphene (u-BVG) toward the accelerated photocatalytic water oxidation reaction. Considering the Mott-Schottky heterojunctions at the contact interface in u-BVG, the feasible electron transfer from excited BiVO4 to graphene facilitates the holes to migrate onto the BiVO4 surface for the water oxidation reaction. Compared with the conventional synthesis strategies, our strategy avoids the introduction of Cl impurities. This modification allows for not only a ca. 0.1 eV deeper valence band edge position to generate holes with a stronger oxidation potential but the extraction of the impurity level to suppress the carrier recombination. And density functional theory calculations are in accordance with the above results. Impressively, these merits endow the u-BVG with ca. 16.8 times growth in the amount of ˙OH radicals derived from OH-/H2O oxidation, an over 260% enhancement in O2 yield and a 1.6-fold increase in the apparent quantum efficiency relative to the impure counterpart. This work paves the way for the reconstruction of graphene-based binary systems with high performance in solar-to-chemical energy conversion.

Enriched Surface Oxygen Vacancies of Photoanodes by Photoetching with Enhanced Charge Separation.

A facile photoetching approach is described that alleviates the negative effects from bulk defects by confining the oxygen vacancy (Ovac ) at the surface of BiVO4 photoanode, by 10-minute photoetching. This strategy could induce enriched Ovac at the surface of BiVO4 , which avoids the formation of excessive bulk defects. A mechanism is proposed to explain the enhanced charge separation at the BiVO4 /electrolyte interface, which is supported by density functional theory (DFT) calculations. The optimized BiVO4 with enriched surface Ovac presents the highest photocurrent among undoped BiVO4 photoanodes. Upon loading FeOOH/NiOOH cocatalysts, photoetched BiVO4 photoanode reaches a considerable water oxidation photocurrent of 3.0 mA cm-2 at 0.6 V vs. reversible hydrogen electrode. An unbiased solar-to-hydrogen conversion efficiency of 3.5 % is realized by this BiVO4 photoanode and a Si photocathode under 1 sun illumination.

Enriched Surface Oxygen Vacancies of Photoanodes by Photoetching with Enhanced Charge Separation

AbstractA facile photoetching approach is described that alleviates the negative effects from bulk defects by confining the oxygen vacancy (Ovac) at the surface of BiVO4 photoanode, by 10‐minute photoetching. This strategy could induce enriched Ovac at the surface of BiVO4, which avoids the formation of excessive bulk defects. A mechanism is proposed to explain the enhanced charge separation at the BiVO4 /electrolyte interface, which is supported by density functional theory (DFT) calculations. The optimized BiVO4 with enriched surface Ovac presents the highest photocurrent among undoped BiVO4 photoanodes. Upon loading FeOOH/NiOOH cocatalysts, photoetched BiVO4 photoanode reaches a considerable water oxidation photocurrent of 3.0 mA cm−2 at 0.6 V vs. reversible hydrogen electrode. An unbiased solar‐to‐hydrogen conversion efficiency of 3.5 % is realized by this BiVO4 photoanode and a Si photocathode under 1 sun illumination.

Effects of morphology on the visible-light-driven photocatalytic and bactericidal properties of BiVO4/CdS heterojunctions: A discussion on photocatalysis mechanism

BiVO4/CdS composites with different morphologies and mass ratios were successfully prepared via a facile deposition-precipitation method by adding different dispersants. Compared with spherical BiVO4 (BS), sheet-like BiVO4 nanoarrays (BA) showed higher (020) exposed areas, as confirmed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). X-ray photoelectron spectroscopy (XPS) revealed further details on the microstructure of the composites namely, CdS was deposited on the surface of BiVO4 forming an S-(111) interface layer. The photocatalytic properties of the samples were tested by studying the degradation of Rhodamine B (RhB) and the sterilization of Escherichia coli (E. coli) under visible-light irradiation. The BAC-60 sample showed the best photocatalytic performance among all the catalysts owing to its: (i) improved high separation efficiency of the photo-induced charge carriers and (ii) high exposure activity of the (020) plane. Electrochemical tests with non-equilibrium carrier injection and free radical trapping experiments are introduced to analyze the mechanism, such as the effects of different crystal planes on the photocatalytic reaction and the flow direction of carriers at the CdS–BiVO4 interface.

The improvement of photocatalysis O2 production over BiVO4 with amorphous FeOOH shell modification

A novel amorphous FeOOH modified BiVO4 photocatalyst (A-FeOOH/BiVO4) was successfully produced and characterized by various techniques. The results showed that amorphous FeOOH with about 2 nm thickness evenly covered on BiVO4 surface, which caused resultant A-FeOOH/BiVO4 exhibiting higher visible light photocatalytic performance for producing O2 from water than BiVO4. When the covered amount of amorphous FeOOH was 8%, the resultant photocatalyst possessed the best photocatalytic performance. To find the reasons for the improvement of photocatalytic property, electrochemical experiments, DRS, PL and BET, were also measured, the experimental results indicated that interface effect between amorphous FeOOH and BiVO4 could conduce to migration of photogenerated charge, and exhibit stronger light responded capacity. These positive factors promoted A-FeOOH/BiVO4 presenting improved the photocatalytic performance. In a word, the combination of amorphous FeOOH with BiVO4 is an effective strategy to conquer important challenges in photocatalysis field.

Mo-doped porous BiVO4/Bi2S3 nanoarray to enhance photoelectrochemical efficiency for quantitative detection of 17β-estradiol

A new porous nanoarray is constructed as sensing platform of photoelectrochemical (PEC) biosensor for detection of 17β-estradiol (E2) by using aptamer. The molybdenum (Mo) ions doped into porous bismuth vanadate (Mo-p BiVO4) nanoarray by electrodeposition of BiOI nanoarray. Then, the bismuth sulfide (Bi2S3) nanoparticles are grown in-situ on the surface of Mo-p BiVO4 by the self-sacrificial synthesis method to form novel Mo-p BiVO4/Bi2S3 heterojunction. Herein, the Mo-p BiVO4/Bi2S3 heterojunction presents a high PEC signal because of Mo-p BiVO4 could increase electron-hole separation yield by supplying additional free electrons, furthermore the heterojunction of Mo-p BiVO4/Bi2S3 could promote ultrafast transfer of charge and inhibit the recombination of e−/h+ pairs by presenting cascade band-edge levels under irradiation of the visible light. Moreover, the nanoarray structure has large specific surface area, which could accelerate electron transfer and provide large number of binding sites to immobilize aptamer. This PEC aptamer sensor exhibits high sensitivity with a detection limit 3.2 × 10-4 pM and a good photocurrent response toward target E2 in the range of 1 × 10-3 - 5 × 102 pM. Good specificity and stability are acquired for analysis of E2 in human urine. Importantly, this designed sensor platform of Mo-p BiVO4/Bi2S3 heterojunction provides a new promising application for other environmental estrogen analysis.

Ru Nanoparticles Supported on Oxygen‐Deficient 3DOM BiVO4: High‐Performance Catalysts for the Visible‐Light‐Driven Selective Oxidation of Benzyl Alcohol

AbstractDeveloping novel photocatalysts for green synthesis of important organic intermediates under mild conditions is of great significance in industry. In this work, we synthesized the oxygen‐deficient three‐dimensionally ordered macroporous (3DOM) BiVO4‐supported nanosized Ru (xRu/3DOM BiVO4, x=0.24–2.16 wt %) catalysts by the polymethyl methacrylate‐templating, ethylene glycol reduction, and post‐thermal treatment methods. Physicochemical properties of the materials were characterized using the various techniques, and their catalytic activities for the visible‐light‐driven selective oxidation of benzyl alcohol to benzaldehyde were measured. It is found that the Ru nanoparticles (NPs) with a size of 1.2–1.5 nm were uniformly dispersed on the surface of 3DOM BiVO4, which gave rise to a significant enhancement in photocatalytic activity. Benzyl alcohol conversion first went up and then dropped down with the rise in loading of Ru NPs. The 0.95Ru/3DOM BiVO4−Ar‐300 sample was thermally treated in an Ar flow at 300 °C for 4 h showed the highest benzyl alcohol conversion (78 %) with a benzaldehyde selectivity of 100 % (benzaldehyde formation rate was 1380 μmol/(g h) after 6 h of illumination) and good photocatalytic stability. The high dispersion of Ru NPs and formation of oxygen vacancies in 3DOM BiVO4 improved separation and transfer efficiency of the photogenerated electrons/holes and increased the superoxide radical concentration. In addition, the possible mechanism of benzyl alcohol oxidation over 0.95Ru/3DOM BiVO4−Ar‐300 was also discussed. The oxygen‐deficient 3DOM BiVO4‐supported Ru NPs have promising applications for selective oxidation of organics.

Preparation of highly crystalline quaternary heterostructure catalyst for hydrogen evolution under solar light: Improved photoexcited charge separation

Synthesis of Ag/AgVO3@CdS/BiVO4 heterostructure photocatalysts by the photoreduction strategy and tested for H2 evolution under artificial solar irradiation. The effects of Ag/AgVO3@CdS/BiVO4 heterostructure on the crystal phase, visible absorption, morphology, strong interactions, and charge carrier separations were analyzed by series of characterization techniques. Based on photocatalytic test, 1Ag/AgVO3@CdS/BiVO4 exhibited the highest solar light-driven activity for hydrogen production (105,541 μmol/g) and with an apparent quantum yield. As a results, the metallic silver and AgVO3 particles were formed and located on the surface of the monoclinic BiVO4 and CdS nanorods represented as charge carrier bridges and electron tricking centers. The Ag/AgVO3@CdS/BiVO4 heterostructures with suitable oxidation-reduction energy levels could enhance charge carrier separation and engineering a broad spectral response by extending more light absorption capacity. The synergetic phenomenon and plasmonic Ag nanoclusters in this heterostructure favorable for creation of photoexcited electron clouds at CB of CdS.

Understanding Reaction Kinetics by Tailoring Metal Co-catalysts of the BiVO4 Photocatalyst.

In this study, the reaction mechanisms of metal–semiconductor composites used as photocatalysts were demonstrated by first preparing bismuth vanadate (BiVO4) and then performing photodeposition of metal nanoparticles. The photocatalytic activity of metal–BiVO4 (M–BiVO4, where M = Pt, Au, Ag) composites were evaluated through dye decomposition under UV–vis irradiation. The photocatalytic efficiency was significantly enhanced after Pt deposition as compared to other M–BiVO4 composites. The size or shape of BiVO4 was not the main factor for the efficiency of Pt–BiVO4. However, a deposited Pt co-catalyst was essential for the photocatalytic decomposition of dye on the BiVO4 surface. Radical scavengers were employed to elucidate the reaction mechanism during the photocatalytic reaction with the Pt–BiVO4 composite. This study provides details on the reaction mechanism of the photocatalytic reaction on Pt at the BiVO4 surface under solar irradiation.

Photocatalytic degradation of paracetamol on Pd–BiVO4 under visible light irradiation

In this study, Pd–BiVO4 bearing highly dispersed Pd nanoparticles was prepared from pure BiVO4 using an impregnation method. The pure BiVO4 and Pd–BiVO4 catalysts were characterized by X-ray diffraction, scanning electron microscopy, UV–visible diffuse reflection, transmission electron microscopy, and X-ray photoelectron spectroscopy. The results showed that the prepared catalysts had a monoclinic scheelite structure and exhibited a flake-like morphology. Pd–BiVO4 showed a distinct response in the visible light region, with an extended absorption edge at 550 nm. According to the Scherrer formula, the nanocrystal particle sizes of the BiVO4 and Pd–BiVO4 catalysts were 35 and 28 nm, respectively. Highly dispersed Pd nanoparticles with sizes of 2.5 ± 0.5 nm were observed on the BiVO4 surface. Two Pd valence states, Pd(II) and Pd(0), were identified in a 2:1 ratio. Pd–BiVO4 exhibited excellent activity for paracetamol (PCT) degradation, with 100% removal achieved in 1 h under visible light irradiation. During degradation, the mineralization ratio reached up to 40% total organic carbon removal. Two highly active species, namely, hydroxyl and superoxide radicals, were determined by electron spin resonance (ESR). Furthermore, the potential degradation of PCT in this system was proposed based on intermediate information obtained using HPLC-MS and Gauss analysis. The high dispersion and small size of Pd nanoparticles might favor the removal of emerging contaminants using the Pd–BiVO4 photocatalytic system.

(Invited) Hole Extraction Layer Boosting Photoelectrochemical Solar Water Splitting

As the development of oxygen evolution co-catalysts (OECs) is being actively undertaken, the tailored integration of those OECs with photoanodes is expected to be a plausible avenue for achieving highly efficient solar-assisted water splitting. Here, we demonstrate that a black phosphorene (BP) layer, inserted between the OEC and BiVO4 can improve the photoelectrochemical performance of pre-optimized OEC/BiVO4 (OEC: NiOOH, MnOx, and CoOOH) systems by 1.2~1.6-fold, while the OEC overlayer, in turn, can suppress BP self-oxidation to achieve a high durability. A photocurrent density of 4.48 mA·cm-2 at 1.23 V vs reversible hydrogen electrode (RHE) is achieved by the NiOOH/BP/BiVO4 photoanode. It is found that the intrinsic p-type BP can boost hole extraction from BiVO4 and prolong holes trapping lifetime on BiVO4 surface. This work sheds light on the design of BP-based devices for application in solar to fuel conversion, and also suggests a promising nexus between semiconductor and electrocatalyst.

Theoretical treatment of semiconductor heterojunctions for photocatalysis: the WO3/BiVO4 interface

The valence and conduction band (CB) alignments and the nature of the WO3/BiVO4 heterojunction have been analysed in detail based on hybrid functionals density functional theory calculations. The WO3/BiVO4 junction is widely studied in photocatalysis for its capability to reduce electron–hole recombination and to improve efficiency. This is assumed to be due to a favourable band alignment of the junction’s components, which generates a flow of negative charge carriers towards WO3, and positive ones towards BiVO4. This conclusion is often based on the properties of the two isolated, non-interacting units. Here, we propose an explicit interface model where the (0 0 1) surface of WO3 is put in contact with the (0 1 0) surface of BiVO4 rotated by about 45°, which leads to a small strain and a favourable cation-anion matching. The interface displays a moderate charge transfer and a small interface dipole. This leads to only moderate effects on the band alignment, which remains qualitatively similar to that obtained from the two independent oxides. We also considered in detail the role of the amount of exact exchange used in the description of the heterojunction, and in particular of the BiVO4 component, for which rather different hybrid functional approaches have been proposed in the literature.

Amorphous Co–Cu–Al mixed metal oxide nanoparticles modified BiVO4 to improve photocatalytic desulfurization

Amorphous Co–Cu–Al nanocomposite modified BiVO4 (CoCuAl/BiVO4) has been synthesized. The results revealed that CoCuAl nanocomposite with the size of around 10 nm evenly loaded on BiVO4 surface, which could enhance visible light response capacity and charge separated rate of BiVO4. When they were used for visible light photocatalytic desulfurization, desulfurization efficiency of thiophene could be sharply improved over CoCuAl/BiVO4. Obviously, this work provide a simple and economic method for modifying photocatalyst property.

Investigation of Transfer and Transport Kinetics on the Cobalt-Borate Catalyzed BiVO4 Photoanode.

BiVO4 is considered as promising photoanode material for solar water splitting [1]. Its performance is limited by slow water oxidation kinetics and poor charge separation [2]. To enhance water oxidation kinetics of BiVO¬4, Oxygen evolution catalyst (OEC) has been incorporated on the surface of photoanode. Cobalt borate (Co-Bi) is known as an excellent catalyst for water oxidation [3, 4]. In this work, we have incorporated Co-Bi as OEC on the surface of BiVO4 to enhance charge transfer and transport efficiency and hence overall enhancement of water oxidation kinetics. Mo-doped BiVO4 was coated on FTO by spin coating technique using precursor solution followed by calcination at 500oC for 3 hours. After formation of BiVO4, Co-Bi has been incorporated on photoanode surface by photoelectrochemical deposition technique. Photoanode material were named as S1: BiVO4 and S2: BiVO4/Co-Bi Photoelectrochemical activity was performed by chopped light voltammetry. Photocurrent of S2 was found to increase 36.61% of S1 at 0.95V which indicated that Co-Bi increases the surface catalytic activity of BiVO4. The onset potential was also found to shift cathodically on incorporation of Co-Bi. Charge transfer and transport efficiency were found to increase from 67% to 70% and 32% to 50% respectively upon incorporation of Co-Bi. These data shows that OEC facilitates separation of photogenerated charge and enhancement of interfacial charge transfer efficiency. Enhancement of Charge transport efficiency indicated that Co-Bi works as hole collector and hence mobility of photogenerated hole increases many folds. Further interfacial charge transfer efficiency was measured by electrical impedance spectroscopy (EIS). The Rct value was found to decrease from 2677Ω to 334Ω and relaxation frequency was found to increase from 52Hz to 185Hz which suggests faster charge transfer at the interface. Further, kinetics was measured from scanning electrochemical microscopy (SECM) technique. In this study probe was approached to substrate by probe approach technique (PAC) with different bias potential at the substrate and measure feedback current at the probe to study the hole transfer rate from substrate to the analyte. In this study 0.1m ferricyanide solution was used as probe redox. The interfacial charge rate constant was found 3-7×10-3 cm/sec with increasing positive bias on the substrate which suggest greater band bending at more positive potential and hence higher rate constant of hole transfer. Further localized kinetics was measured by SECM imaging on the substrate in feedback mode. Higher cathodic current shows better catalytic site for hole transfer. Co-Bi incorporation on the BiVO4 surface enhances overall efficiency of water spitting.

Oxygen-Defective Ultrathin BiVO4 Nanosheets for Enhanced Gas Sensing

BiVO4 nanomaterials are potentially applicable in gas sensing, but the sensing performance is limited by the less active sites on the BiVO4 surface. In this work, we propose a strategy to improve the gas-sensing performance of BiVO4 by forming ultrathin nanosheets and introducing oxygen vacancies, which increase the surface active sites. Two-dimensional (2D) BiVO4 nanosheets with oxygen vacancies are prepared through a colloidal method with the assistance of nitric acid. Gas sensors based on the oxygen-defective 2D ultrathin BiVO4 nanosheets exhibit an enhanced sensing response, which is 3.4 times higher than those of the sensors based on oxygen-abundant BiVO4 nanosheets. The density functional theory calculation is employed to uncover the promoting effects of oxygen vacancies on enhancing the O2 adsorption capability of BiVO4 nanosheets. This work is not only expected to build a wide range of 2D metal oxide semiconductors with a high gas-sensing performance but also gives an insight into the mechanism of the enhanced response induced by the oxygen vacancies, which will be a guideline for further designing high-performance sensing materials.

The Importance of the Interfacial Contact: Is Reduced Graphene Oxide Always an Enhancer in Photo(Electro)Catalytic Water Oxidation?

Optimizing interfacial contact between graphene and a semiconductor has often been proposed as essential for improving their charge interactions. Herein, we fabricated bismuth vanadate-reduced graphene oxide (BiVO4/rGO) composites with tailored interfacial contact extents and revealed their disparate behavior in photoelectrochemical (PEC) and powder suspension (PS) water oxidation systems. BiVO4/rGO with a high rGO coverage on the BiVO4 surface (BiVO4/rGO HC) exhibited an 8-fold enhancement in the PEC photocurrent density with respect to neat BiVO4 at 0 V versus Ag/AgCl, while BiVO4/rGO with a low rGO coverage (BiVO4/rGO LC) gave a lesser 3-fold enhancement. In contrast, BiVO4/rGO HC delivered a detrimental effect, while BiVO4/rGO LC exhibited an enhanced performance for oxygen evolution in the PS system. The phenomenon is attributed to changes in the hydrophobicity of the BiVO4/rGO composite in conjunction with the interfacial contact configuration. A better BiVO4/rGO interfacial contact was found to improve the charge separation efficiency and charge transfer ability of the composite material, explaining the superior PEC performance of BiVO4/rGO HC. Additionally, optimization of the interfacial contact extent was revealed to further improve the energetics of the composite material, as evidenced by a Fermi level shift to a more negative potential. However, the high hydrophobicity of BiVO4/rGO HC arising from the higher rGO reduction extent triggered poor water miscibility, reducing the surface wettability and therefore hampering the photocatalytic O2 evolution activity of the sample. The study underlines water miscibility as a governing issue in the PS system.

High Photocatalytic Performance of Pd/PdO‐Supported BiVO4 Nanoparticles for Rhodamine B Degradation under Visible LED Light Irradiation

AbstractPd/PdO‐decorated BiVO4 nanoparticles were prepared by two‐step router: (i) monoclinic scheelite BiVO4 nanoparticles were fabricated via the co‐precipitation process in the presence of urea; (ii) Pd/PdO was decorated BiVO4 surface by the combination of by precipitation method and annealing process. The as‐synthesized catalysts were characterized by X‐ray powder diffraction (XRD) analysis, Raman spectra, X‐ray photoelectron (XPS) spectra, UV‐visible diffuse reflectance (UV‐vis DRS) spectra, and photoluminescence (PL) spectroscopy. The photocatalytic performance of Pd/PdO‐decorated BiVO4 samples exhibited excellent photodegradation of rhodamine B as well as the OH• radical generation under LED light irradiation as a comparison with the bare BiVO4. This excellent outcome is due to the reduced electron/hole recombination of Pd/PdO‐decorated BiVO4 samples, which was confirmed by PL characterization. Therefore, the fabrication of semiconductors with a combination of noble metal/oxides are good candidates for enhancement of their photocatalytic performance.