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Membrane separation processes are promising methods for wastewater treatment. Membrane fouling limits their wider use; however, this may be mitigated using photocatalytic composite materials for membrane preparation. This study aimed to investigate photocatalytic polyvinylidene fluoride (PVDF)-based nanocomposite membranes for treating model dairy wastewater containing bovine serum albumin (BSA). Membranes were fabricated via physical coating (with TiO2, and/or carbon nanotubes, and/or BiVO4) and blending (with TiO2). Another objective of this study was to compare membranes of identical compositions fabricated using different techniques, and to examine how various TiO2 concentrations affect the antifouling and cleaning performances of the blended membranes. Filtration experiments were performed using a dead-end cell. Filtration resistances, BSA rejection, and photocatalytic cleanability (characterized by flux recovery ratio (FRR)) were measured. The surface characteristics (SEM, EDX), roughness (measured by atomic force microscopy, AFM), wettability (contact angle measurements), and zeta potential of the membranes were also examined. Coated PVDF membranes showed higher hydrophilicity than the pristine PVDF membrane, as evidenced by a decreased contact angle, but the higher hydrophilicity did not result in higher fluxes, unlike the case of blended membranes. The increased surface roughness resulted in increased reversible fouling, but decreased BSA retention. Furthermore, the TiO2-coated membranes had a better flux recovery ratio (FRR, 97%) than the TiO2-blended membranes (35%). However, the TiO2-coated membrane had larger total filtration resistances and a lower water flux than the commercial pristine PVDF membrane and TiO2-blended membrane, which may be due to pore blockage or an additional coating layer formed by the nanoparticles. The BSA rejection of the TiO2-coated membrane was lower than that of the commercial pristine PVDF membrane. In contrast, the TiO2-blended membranes showed lower resistance than the pristine PVDF membrane, and exhibited better antifouling performance, superior flux, and comparable BSA rejection. Increasing the TiO2 content of the TiO2-blended membranes (from 1 to 2.5%) resulted in increased antifouling and comparable BSA rejection (more than 95%). However, the effect of TiO2 concentration on flux recovery was negligible.

The efficiency of photocatalytic overall water splitting reactions is usually limited by the high energy barrier and complex multiple electron‐transfer processes of the oxygen evolution reaction (OER). Although bismuth vanadate (BiVO4) as the photocatalyst has been developed for enhancing the kinetics of the water oxidation reaction, it still suffers from challenges of fast recombination of photogenerated electron‐hole pairs and poor photocatalytic activity. Herein, six MII‐CoIII Prussian blue analogues (PBAs) (M=Mn, Fe, Co, Ni, Cu and Zn) cocatalysts are synthesized and deposited on the surface of BiVO4 for boosting the surface catalytic efficiency and enhancing photogenerated carries separation efficiency of BiVO4. Six MII‐CoIII PBAs@BiVO4 photocatalysts all demonstrate increased photocatalytic water oxidation performance compared to that of BiVO4 alone. Among them, the Co−Co PBA@BiVO4 photocatalyst is employed as a representative research object and is thoroughly characterized by electrochemistry, electronic microscope as well as multiple spectroscopic analyses. Notably, BiVO4 coupling with Co−Co PBA cocatalyst could capture more photons than that of pure BiVO4, facilitating the transfer of photogenerated charge carriers between BiVO4 and Co−Co PBA as well as the surface catalytic efficiency of BiVO4. Overall, this work would promote the synthesis strategy development for exploring new types of composite photocatalysts for water oxidation. [ABSTRACT FROM AUTHOR]

The efficiency of photocatalytic overall water splitting reactions is usually limited by the high energy barrier and complex multiple electron‐transfer processes of the oxygen evolution reaction (OER). Although bismuth vanadate (BiVO4) as the photocatalyst has been developed for enhancing the kinetics of the water oxidation reaction, it still suffers from challenges of fast recombination of photogenerated electron‐hole pairs and poor photocatalytic activity. Herein, six MII‐CoIII Prussian blue analogues (PBAs) (M=Mn, Fe, Co, Ni, Cu and Zn) cocatalysts are synthesized and deposited on the surface of BiVO4 for boosting the surface catalytic efficiency and enhancing photogenerated carries separation efficiency of BiVO4. Six MII‐CoIII PBAs@BiVO4 photocatalysts all demonstrate increased photocatalytic water oxidation performance compared to that of BiVO4 alone. Among them, the Co−Co PBA@BiVO4 photocatalyst is employed as a representative research object and is thoroughly characterized by electrochemistry, electronic microscope as well as multiple spectroscopic analyses. Notably, BiVO4 coupling with Co−Co PBA cocatalyst could capture more photons than that of pure BiVO4, facilitating the transfer of photogenerated charge carriers between BiVO4 and Co−Co PBA as well as the surface catalytic efficiency of BiVO4. Overall, this work would promote the synthesis strategy development for exploring new types of composite photocatalysts for water oxidation. [ABSTRACT FROM AUTHOR]

Mo6+ doping increases the photoelectrochemical performance of BiVO4 photoanodes in water oxidation. Herein, the underlying mechanisms is elucidated through a systematic structural, morphological, and photoelectrochemical investigation on photoelectrodes of pure and Mo6+ doped BiVO4 prepared by a novel multistep spin‐coating deposition approach, leading to multilayer flat films with high optical transparency. Transient absorption spectroscopy in the nano‐ to microsecond time scale reveals a longer lifetime of photogenerated holes in the doped films. Besides confirming that Mo6+ ions improve the electron transport in the material bulk, impedance spectroscopy also reveals the crucial role of the dopant on the surface properties of BiVO4 photoanodes. The presence of intra‐bandgap states, acting as traps of photogenerated charge carriers in pure BiVO4, is detected through the build‐up of the interfacial surface state capacitance. The limited activity of pure BiVO4 in water oxidation is largely improved upon 3 at% Mo6+ incorporation, ensuring a more efficient charge carrier transport with respect to pure BiVO4, together with the beneficial passivation of its trap surface states. [ABSTRACT FROM AUTHOR]

Exploring cheap and efficient cocatalysts is particularly important for a photoanode during photoelectrochemical (PEC) water splitting. Herein, we demonstrate that composite CoOx/CuO cocatalyst could efficiently enhance the oxygen evolution activity of BiVO4. The onset potential of BiVO4 shifts negatively from 0.42 to 0.38 V vs. the reversible hydrogen electrode (RHE), and the photocurrent of BiVO4 increases from 0.42 mA cm−2 to 1.58 mA cm−2 at 1.23 V vs. RHE, which increases by about 3.76 times. It was confirmed by subsequent electrochemical and physical characterization that the charge separation and injection efficiency were improved, and the IPCE was also improved. Systematic studies indicate that composite CoOx/CuO cocatalyst exhibits better performance than the single CoOx or CuO cocatalyst for promoting the separation of electron‐hole, and accelerating the surface water oxidation reaction. [ABSTRACT FROM AUTHOR]

Owing to the relatively short hole diffusion length, severe charge recombination in the bulk of bismuth vanadate (BiVO4) is the key issue for photoelectrochemical water splitting. Herein, we design a nanoporous MoO3−x/BiVO4 heterojunction photoanode to promote charge separation. The efficient electron transport properties of oxygen deficient MoO3−x and the nanoporous structure are beneficial for charge separation, leading to a significantly enhanced PEC performance. The optimized MoO3−x/BiVO4 heterojunction photoanode exhibits a photocurrent density of 5.07 mA·cm−2 for Na2SO3 oxidation. By depositing FeOOH/NiOOH dual oxygen evolution cocatalysts to promote surface kinetics, a high photocurrent density of 4.81 mA·cm−2 can be achieved for PEC water splitting, exhibiting an excellent applied bias photon-to-current efficiency of 1.57%. Moreover, stable overall water splitting is achieved under consecutive light illumination for 10 h. We provide a proof of concept for the design of efficient BiVO4-based heterojunction photoanodes for stable PEC water splitting. [ABSTRACT FROM AUTHOR]

Bismuth vanadate (BiVO 4) is a promising n-type photoanode material for photoelectrochemical (PEC) water splitting. However, its activity is impeded by poor charge carrier transport and sluggish oxygen evolution kinetics. In this study, we reports a Fe doping and caffeic acid (CA)/NiFeOOH (NiFe) modification with BiVO 4 photoanode (NiFe/CA/Fe-BiVO 4) to enhance the PEC water oxidation performance and stability. The modified BiVO 4 demonstrates significant advantages in promoting the PEC performance and stability. Specifically, Fe doping via in-situ electro-deposition results in smaller crystal sizes, larger specific surface areas, and more exposed active sites. Furthermore, co-catalyst NiFe connects with Fe-BiVO 4 through CA bridge facilitates a more uniform self-assembly distribution of NiFe on BiVO 4 surface. The NiFe/CA/Fe-BiVO 4 exhibits an excellent photocurrent density of 6.2 mA/cm2 at 1.23 V RHE and demonstrates good stability at 0.8 V RHE. In addition, the composite photoanode shows a high applied bias photon-to-current efficiency (ABPE) value of 2.15% at 0.65 V RHE. EPR and in-situ FTIR confirm the generation of superoxide active species (O 2 - and ·O 2 -) during the PEC water oxidation reaction. [Display omitted] • Density functional theory (DFT) confirmed the changes of electronic states and the direction of charge transfer. • Fe, Co, Ni, Mn and Zn was doped into BiVO 4 and coffee acid (CA) is a coordinating-assisted agent. • The photocurrent density reached 6.2 mA/cm2, accompanied with an ABPE of 2.15%. • EPR and in-situ FTIR confirm the generation of superoxide active species (O 2 - and ·O 2 -). [ABSTRACT FROM AUTHOR]

[Display omitted] • The monoclinic BiVO 4 nanomaterials were prepared by hydrothermal method. • The bandgap structures of BiVO 4 were modified by adjusting the preparation pH. • The visible light oxygen evolution rate of BiVO 4 could achieve 757.62 μmol g−1 h−1. Bismuth vanadate (BiVO 4) has attracted much attention in photocatalytic oxygen evolution due to its chemical stability and environmental friendliness. However, its photocatalytic activity is limited by lower visible light responsiveness and oxidative capacity, which is related to the energy band structure. Here, we solve this problem by successfully preparing monoclinic BiVO 4 nanomaterials with different band gap structures. The primary step of this innovative approach involves solely adjusting the pH using NH 3 ‧H 2 O in the hydrothermal method. Although the reaction process is simple, it's very effective in regulating the energy band structure, leading to an extension of the light response range and an enhancement of oxidizing capacity in the photocatalytic oxygen evolution process. As the results, the optimal oxygen evolution rate under visible light could reach 757.62 μmol h−1 g−1 with FeCl 3 as the sacrificial agent. Finally, the mechanism of photocatalytic oxygen evolution based on the pH regulation effect on the energy band structure was investigated. This study holds significant importance for enhancing the efficiency of BiVO 4 materials in practical applications. [ABSTRACT FROM AUTHOR]

Bismuth vanadate (BiVO4) has been investigated as a photocatalyst of great interest due to its ability to harvest photons efficiently in the visible spectral region. In addition, powdered BiVO4 shows high photochemical stability, good dispersibility, and resistance to corrosion in oxidative conditions. Herein, we report the synthesis of monoclinic or tetragonal BiVO4 particles using different methods, as well as the synthesis of hybrids materials through the combination of cobalt ferrite (CoFe2O4) and BiVO4, and their application in the photodegradation of aqueous solutions of sulfamethoxazole (SMX) under simulated solar radiation. We demonstrate that high-crystallinity single-phase monoclinic BiVO4 was synthesized fast and efficiently using a solid-state method and, in combination with magnetic CoFe2O4 particles, gives rise to a hybrid material that can be easily separated from the reaction medium, by applying an external magnetic field, without the need for further downstream treatments.

Photoelectrochemical (PEC) water splitting is a promising method for transforming solar energy into clean and sustainable energy. However, PEC is severely limited, and they cannot achieve the predicted photocurrent density owing to the severe photochemical deterioration of the electrode and the recombination of photogenerated carriers. In this study, BiVO 4 /Co-diethylenetriamine Penta (methylene phosphonic acid) (BVO/Co-DTPMP) co-catalyst was successfully prepared as a nanoporous photoanode. Diethylenetriamine Penta (methylene phosphonic acid) was crosslinked with Co ions and coated on the BiVO 4 surface by successive ionic layer adsorption and reaction (SILAR) to reduce fast recombination, which correlated with the BiVO 4 photoanode. Various characterization and PEC measurements were conducted, revealing that the co-catalyst thin layer enhanced the charge separation and electrons transfer which significantly affected on the PEC performance of BiVO 4 , and the current density by BVO/Co-DTPMP was 4 mA cm−2 at 1.23 V vs. RHE. Furthermore, the co-catalyst exhibited improved charge transport and long-term stability. [Display omitted] • Amorphous metal organic complex layer (Co-DTPMP) coated on BiVO 4 via SILAR method. • Co-DTPMP layer enhanced the charge separation efficiency & interfacial kinetics. • Coated BiVO 4 enhanced photocurrent density eight times compared to BiVO 4 photoanode. • The photoconversion efficiency of the photoanode reached around 1.37 %. [ABSTRACT FROM AUTHOR]

In this research, the effect of carbon analogs on the photocatalytic activity of BiVO 4 nanocomposites is studied. Nanocomposites of BiVO 4 with carbon nanotube (CNT) and reduced graphene oxide (RGO) were prepared. Scanning electron microscopy (SEM) showed BiVO 4 particles adhered on RGO sheets, and CNTs were attached to the surface of BiVO 4 nanoparticles. Different mass ratios of CNT and RGO were added to BiVO 4 to optimize its photocatalytic activity. The photocatalyst containing 2.5%CNT demonstrates the highest efficiency in the photodegradation of methylene blue as a model organic pollutant. The reason for the greater photodegradation of the BiVO 4 -CNT as compared to BiVO 4 -RGO is analyzed by density functional theory (DFT) calculations, which was due to the different directions of the built-in electric field between carbon analogs and BiVO 4. Furthermore, different photodegradation pathways are governed by pure BiVO 4 , BiVO 4 -RGO, and BiVO 4 -CNT photocatalysts, and a mechanistic study is elucidated based on examining various electron and hole scavengers. • The effect of different weight percentages of CNT and RGO on BiVO 4 photocatalytic activity is studied. • It addresses a comparative investigation of the nature of CNT and RGO addition on BiVO 4 photocatalytic activity. • The mechanism for charge generation and transfer for the photocatalytic degradation is studied. • The experimental results are confirmed by density functional theory (DFT) calculations. [ABSTRACT FROM AUTHOR]

Photo oxidative desulfurization process of DBT. [Display omitted] • A novel photo-oxidative desulfurization process is achieved using Cu-doped/BiVO4 heterojunction. • Catalyst was characterized using various spectroscopic and physical methods. • The composite is used in desulfurization of model fuel under visible light irradiation. • Various parameters for photo0xidative desulfurization process were optimized. • Desulfurization reached up to 93% under the optimized conditions. In the present study, a photocatalytic oxidation desulfurization method is used to eliminate dibenzothiophene as one of the aromatic sulfur derivatives in fuel, using a Cu-TiO 2 /BiVO 4 composite. The structure of the synthesized compounds was characterized by FT-IR and Raman spectroscopy, XRD, DRS, UV–Vis, BET, TEM, FE-SEM, elemental mapping, EDS, XPS, and ICP-MS methods. To find the best results in this photocatalytic system, different parameters such as type of solvent, the amount of photocatalyst, reaction time, amount of oxidizing agent, reaction temperature, and the ratio of extracting solvent to n-heptane as the model fuel was investigated and optimized. Desulfurization tests were carried out including extraction-absorption test (without H 2 O 2), in the absence of photocatalyst, and test in dark conditions followed by oxidation extraction test. The efficiency of this photocatalytic system for dibenzothiophene removal reached 93% under optimal reaction conditions for the model fuel. The photocatalyst was recycled three times and exhibited good efficiency in dibenzothiophene removal. [ABSTRACT FROM AUTHOR]

Nitrogen fixation is a key process that sustains life on Earth. Nitrogenase is the sole enzyme capable of fixing nitrogen under ambient conditions. Extensive research efforts have been dedicated to elucidating the enzyme mechanism and its artificial activation through high applied voltage, photochemistry, or strong reducing agents. Harnessing light irradiation to minimize the required external bias can lower the process's high energy investment. Herein, we present the development of photo-bioelectrochemical cells (PBECs) utilizing BiVO 4 /CoP or CdS/NiO photoanodes for nitrogenase activation toward N 2 fixation. The constructed PBEC based on BiVO 4 /CoP photoanode requires minimal external bias (200 mV) and suppresses O 2 generation that allows efficient activation of the nitrogenase enzyme, using glucose as an electron donor. In a second developed PBEC configuration, CdS/NiO photoanode was used, enabling bias-free activation of the nitrogenase-based cathode to produce 100 μM of ammonia at a faradaic efficiency (FE) of 12%. The ammonia production was determined by a commonly used fluorescence probe and further validated using 1H-NMR spectroscopy. The presented PBECs lay the foundation for biotic-abiotic systems to directly activate enzymes toward value-added chemicals by light-driven reactions. [ABSTRACT FROM AUTHOR]

Monoclinic bismuth vanadate photoanodes promise high efficiency‐to‐cost ratios for photoelectrochemical (PEC) water splitting owing to their suitable band structure and ease of synthesis. However, inadequate charge separation and sluggish oxidation kinetics remain a fundamental challenge. This study investigates bifacially interface engineered BiVO4 photoanodes by considering a seed‐layer and NiOOH oxygen evolution catalyst (OEC) over‐layer to regulate the charge carrier transport and improve the overall PEC water‐splitting performance. The modification of the BiVO4/FTO interface stimulates electron flow towards fluorine‐doped tin oxide (FTO) and a NiOOH over‐layer improves the facile hole transfer from BiVO4 to the electrolyte. Compared to the moderate photocurrent density of a bare BiVO4 photoanode (1.5 mA cm−2), the interface‐engineered Seed_BiVO4_NiOOH photoanode shows a remarkably high (≈3.4 times higher) photocurrent density of 5.10 mA cm−2 at 1.23 V vs reversible hydrogen electrode with impressive long‐term stability over 9 h under illumination. The optimally interface engineered Seed_BiVO4_NiOOH photoanode shows an excellent photoconversion efficiency (1.83%), with significant improvement in bulk charge separation efficiency. This work presents a promising strategy for the development of a highly stable PEC water‐splitting device and eliminates the intrinsic material shortcomings of the bare BiVO4 photoanode by modulating the carrier transport via bifacial interface engineering. [ABSTRACT FROM AUTHOR]

The efficient degradation of a toxic antibiotic from an aqueous solution is essential for environmental protection. Our research aimed to fabricate a bismuth vanadate (BiVO4) catalyst via a facile hydrothermal method. The prepared catalyst exhibited a monoclinic phase with a band gap energy of 2.33 eV, indicating the excellent visible-light-active properties of a semiconductor. The photocatalytic performance of the synthesized BiVO4 catalyst was studied by determining the removal of tetracycline (TC) and oxytetracycline (OTC) antibiotics. After 240 min, under sunlight conditions, a high performance of 72% and 83% degradation of TC and OTC, respectively, was achieved. The photocatalytic degradation of the antibiotics correlates well with a first-order reaction, with a high rate constant of 0.0102 min−1. Photogenerated electrons and holes played an important role in the removal of the pollutant. After photocatalytic study, the structural stability of the prepared bismuth vanadate photocatalyst was confirmed. The photocatalyst provided a promising performance even after five successive runs. The result indicates the excellent cycling ability of the sample. The present work demonstrates a promising route for the preparation of a BiVO4 catalyst for the complete removal of toxic antibiotics in aqueous solutions. [ABSTRACT FROM AUTHOR]

The aim of this research was to study the effect of temperature on the adhesion and disinfection activities of an Ag+-doped BiVO4 (Ag+/BiVO4) coating. Ag+/BiVO4 was prepared by a sol–gel method, and spraying was used as the deposition method of coating. X-ray diffraction patterns showed that the monoclinic scheelite phase of the samples was unchanged by annealing at 450–650 °C. Scanning electron microscopy results showed that, at high temperatures, the particles melted and formed a dense coating, and the roughness of the coating decreased after initially increasing. The adhesion and disinfection activities were evaluated by ASTM D3359-08 and disinfection experiments. The results showed that the samples modified by silver had a good disinfection activity when annealed in the range of 450–650 °C. The adhesion increased upon increasing the annealing temperature. The sample annealed at 650 °C showed the best coating adhesion and completely killed Escherichia coli, Staphylococcus aureus, Shigella, and Salmonella after 2 h of visible-light irradiation. [ABSTRACT FROM AUTHOR]

Metal oxide semiconductors have shown considerable potential for photoelectrochemical water‐splitting. However, no ideal material has emerged which benefit from both an attractive sunlight absorption and efficient charge transport properties. In this work, we show that decorating photoanodes with high refractive index nanoparticles such as amorphous titania can result in reduced reflection losses at the electrolyte/photoanode interface, thereby increasing the performances under illumination from the electrolyte side. A proof of concept is obtained for a bismuth vanadate photoanode including a surface catalyst and a hematite photoanode. The photocurrent density and external quantum efficiency are improved by up to 10 % upon nanoparticle decoration, quantitatively matching the decrease in reflectance. Simulations show that a similar enhancement happens when a thick bismuth vanadate photoanode with optimal charge transport properties is considered, thereby suggesting that this strategy can improve photoanodes suffering from high reflection losses regardless of the bare sample performance. [ABSTRACT FROM AUTHOR]

The catalytic reactivity and photoactivity of WO 3 and BiVO 4 oxide semiconductors have general obstacles as electrodes in emergent photo-electrochemical (PEC) hydrogen evolution applications. The present work comprises the integration of photocatalyst with wide visible photon absorption material which is vital for hydrogen evolution in photo-electrocatalytic water splitting. Herein, the 1D WO 3 NWs have been integrated with stable water oxidation photocatalysts of BiVO 4 and Bi 2 S 3 as a photoanode (Bi 2 S 3 /BiVO 4 /WO 3) for photoelectrochemical hydrogen evolution reactions. The morphological variations in the Bi 2 S 3 /BiVO 4 /WO 3 heterostructure manifest catalytic activity and rapid charge transfer characteristics owing to band alignment and a wide range of visible photon absorption. The optimized Bi 2 S 3 /BiVO 4 /WO 3 multidimensional photoanode accomplishes a superior photocurrent density of 1.52 mA/cm2, a seven-fold higher than pristine WO 3 photoanode counterpart (0.2 mA/cm2) at 1 V vs. RHE. A prodigious lowest onset potential of −0.01 V vs. RHE) has been achieved which enables very high solar to hydrogen conversion. The photoelectrode with entangled morphology such as nanosheets, nanocrystals and nanorods expanded their surface to volume ratio having enhanced catalytic performance. The hybrid photoanodes have demonstrated the lowest charge transfer resistance of 360 Ohm/cm2 with a 7-fold rise in hydrogen evolution performance. The resultant triadic Bi 2 S 3 /BiVO 4 /WO 3 heterostructure appeared to be an emerging stable photo-electro catalyst for hydrogen evolution applications. [Display omitted] • A multidimensional Bi 2 S 3 /BiVO 4 /WO 3 is prepared by hydrothermal and SILAR method. • The hetero-structure upholds photo-excitation and enhances carriers' kinetics. • The open triadic structure improves the hydrogen evolution. • A type II band alignment in Bi 2 S 3 /BiVO 4 /WO 3 hetero-structure is proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • A self-transformation strategy is proposed to synthesize oxygen-vacancy-rich Co(O)OH cocatalyst. • The ultrathin Co(O)OH nanolayer facilitates charge transfer/separation and water oxidation kinetics. • The BiVO 4 /Co(O)OH hybrid photoanode exhibits a high photocurrent density of 4.2 mA cm−2. • The oxygen vacancies in Co(O)OH framework play a crucial role in improving the PEC activity. Surface charge recombination is regarded as a detrimental factor that severely downgrades the photoelectrochemical (PEC) performance of bismuth vanadate (BiVO 4). In this work, we demonstrate defect-rich cobalt (oxy)hydroxides (Co(O)OH) as an excellent cocatalyst nanolayer sheathed on BiVO 4 to substantially improve the PEC water oxidation activity. The self-transformation of metal–organic framework produces an ultrathin Co(O)OH layer rich in oxygen vacancies, which could serve as a powerful hole extraction engine to promote the charge transfer/separation efficiency as well as an excellent oxygen evolution reaction catalyst to accelerate the surface water oxidation kinetics. As a result, the BiVO 4 /Co(O)OH hybrid photoanode achieves remarkably inhibited surface charge recombination and presents a prominent photocurrent density of 4.2 mA cm−2 at 1.23 V vs. RHE, which is around 2.6-fold higher than that of the pristine BiVO 4. Moreover, the Co(O)OH cocatalyst nanolayer significantly reduces the onset potential of BiVO 4 photoanodes by 200 mV. This work provides a versatile strategy for rationally preparing oxygen-vacancy-rich cocatalysts on various photoanodes toward high-efficient PEC water oxidation. [ABSTRACT FROM AUTHOR]

In this work, NiO modified BiVO4 (BiVO4/NiO) nanocomposite was synthesized using hydrothermal and calcination method. The composite of BiVO4/NiO, further employed as a low-overpotential photoanode, was consisted of BiVO4 nanoparticles and NiO nanosheets, in which the BiVO4 nanoelectrode served as the matrix for the attachment of NiO nanosheets. Photoelectrochemical (PEC) tests show that BiVO4/NiO displayed improved PEC performance compared with pure BiVO4. The BiVO4/NiO photoanode delivers a photocurrent density of 1.2 mA/cm2 at 1.23 V vs. RHE in a Na2SO4 electrolyte under an AM 1.5G solar simulator, which is 0.3 mA/cm2 higher than pure BiVO4 photoanode. Meanwhile, the onset potential also generates a 350 mV cathodic shift. The enhanced performance of the BiVO4/NiO nanocomposite is attributed to NiO unique lamellar structure capable of providing a large number of active sites. Measurements of electrochemical impedance spectra (EIS) and the incident photon-to-current efficiency (IPCE) illustrate that the enhanced PEC activities are ascribed to the improved charge carrier separation/transport and the promoted water oxidation kinetics furnished by the decoration of NiO cocatalyst.

Photoelectrochemical water splitting based on nanostructured bismuth vanadate (BiVO4) can be a promising strategy to produce low‐cost and green H2 to replace fossil fuels and realize carbon neutrality. Herein, a simple chemical way to realize in situ carbon doping into BiVO4 crystalline structure is designed and obtained carbon‐doped BiVO4, namely C‐BiVO4, can improve the electronic conductivity of BiVO4. In addition, the introduction of the synthesized carbon quantum dots (CQDs) as a co‐catalyst, immobilizes CQDs onto the C‐BiVO4 nanosheet and acquires the optimized C‐BiVO4/CQDs heterogeneous structure, which not only boosts light absorption, but also enhances the separation and transfer of the photo‐generated charges. Stemming from the dual carbon actions, the as‐prepared C‐BiVO4/CQDs photoanode exhibits an excellent photocurrent density of 4.83 mA cm−2 at 1.23 V versus the RHE without the use of any hole scavengers. To assure the practical application of the sensitive photocatalyst, a polyaniline layer is electroplated onto the C‐BiVO4/CQDs catalyst as a conducting, electroactive, and protective layer to sustain a remarkable long‐term photocurrent density of 2.75 mA cm−2 for 9 hours. This work suggests that the proposed low‐cost, environmentally friendly dual carbon actions can modify photocatalyst and achieve green production of H2. [ABSTRACT FROM AUTHOR]

In this work, we investigate the crucial effect of Er dopant on structural, morphological and optical properties of BiVO4 prepared by one-step sonochemical process. The Er doping content was varied from 0% to 10%. The structural and morphological characterization were performed by X-ray diffraction technique (XRD), Raman spectroscopy and scanning electron microscopy. XRD and Raman spectra reveal the structural transition from monoclinic to tetragonal structure induced by Er dopant. Optical properties of the prepared samples were investigated by diffuse reflectance technique and the corresponding optical band gaps were calculated indicating two optical band gaps of two major phases of the doped samples. The Er dopant has highly influence on an enhancement in photocatalytic performance under visible irradiation of BiVO4 as doping content is 8%. This improved performance could be due to the size reduction and morphological change due to phase transformation induced by Er dopant accompanying mixture of optical band gaps that can assist the retardment of electron-hole pair recombination. [ABSTRACT FROM AUTHOR]

Recently, bismuth vanadate (BiVO 4) has attracted substantial attention for photocatalytic applications owing to its many advantages as semiconductor to drive water oxidation. Despite possessing promising characteristics to be applied in photocatalysis, the fast electron-hole pairs recombination is still one of the drawbacks involving this semiconductor. The use of conformal layers to minimize such limitation and to improve charge separation is the aim of this work. Herein, we report on the use of SnO 2 as a conformal coating layer over the BiVO 4 surface for O 2 evolution reaction. The incorporation of SnO 2 over the BiVO 4 surface showed the beneficial effect in O 2 evolution compared to the pristine material, resulting in 490 μmol after 6 h of irradiation. Transient absorption and surface photovoltage spectroscopies indicate enhanced charge carrier separation and transport by passivating BiVO 4 with SnO 2 thin layer. Even though the O 2 evolution tests in this work were carried out without the presence of a co-catalyst, the use of a thin conformal coating of SnO 2 over BiVO 4 showed promising results for further studies. [Display omitted] • BiVO 4 @SnO 2 increased the amount of O 2 from 69 to 490 μmol after 6 h of irradiation. • The presence of SnO 2 protected BiVO 4 against charge carrier recombination. • SPS and TAS measurements confirm better charge carrier separation. [ABSTRACT FROM AUTHOR]

Highlights: Two types of BiVO4/TiO2 heterostructure photoanodes comprising TiO2 nanorods (NRs) and TiO2 nanoflowers (NFs) with different (001) and (110) crystal facets, respectively, were designed. The higher photoactivity of BiVO4/TiO2 NFs than BiVO4/TiO2 NRs was attributed to the improvement of charge separation by the TiO2 NFs. The formation of type II band alignment between BiVO4 nanodots and TiO2 NFs expedited electron transport and reduced charge recombination.Although bismuth vanadate (BiVO4) has been promising as photoanode material for photoelectrochemical water splitting, its charge recombination issue by short charge diffusion length has led to various studies about heterostructure photoanodes. As a hole blocking layer of BiVO4, titanium dioxide (TiO2) has been considered unsuitable because of its relatively positive valence band edge and low electrical conductivity. Herein, a crystal facet engineering of TiO2 nanostructures is proposed to control band structures for the hole blocking layer of BiVO4 nanodots. We design two types of TiO2 nanostructures, which are nanorods (NRs) and nanoflowers (NFs) with different (001) and (110) crystal facets, respectively, and fabricate BiVO4/TiO2 heterostructure photoanodes. The BiVO4/TiO2 NFs showed 4.8 times higher photocurrent density than the BiVO4/TiO2 NRs. Transient decay time analysis and time-resolved photoluminescence reveal the enhancement is attributed to the reduced charge recombination, which is originated from the formation of type II band alignment between BiVO4 nanodots and TiO2 NFs. This work provides not only new insights into the interplay between crystal facets and band structures but also important steps for the design of highly efficient photoelectrodes. [ABSTRACT FROM AUTHOR]

In this work, Mn-incorporated BiVO4 nanoparticles with different Mn contents (0–5%) were synthesized by one-step sonochemical process. Structural phase of Mn-incorporated BiVO4 nanoparticles was extensively carried out by X-ray diffraction technique. The XRD results show that the structural phase of BiVO4 belongs to the monoclinic principal structure while the secondary phases of MnO, Mn2O3, and Mn3O4 structures are noticed in Mn-loaded samples. Chemical bondings of Mn-incorporated BiVO4 nanoparticles were characterized with Raman spectroscopy. Relevant chemical bondings confirm the existence of VO43− tetrahedron and the V–O band by Raman spectra. Diffuse reflection spectroscopy and FE-SEM were employed to examine their optical and morphological properties, respectively. The results indicate that the incorporation of Mn can induce the red-shift of optical absorption edge in visible range, which can decrease the optical band gap of BiVO4. Morphology of all samples demonstrates the difference in shape of the compounds with the incorporation of Mn contents. Oxidation number and local structure of Mn-incorporated BiVO4 nanoparticles were investigated by X-ray absorption spectroscopy. XAS results demonstrate that oxidation number of all elements correspond to Mn2+/Mn3+, Bi3+, and V5+ ions. The normalized Mn K-edge XANES spectra suggest that Mn atoms would not locate at the local site of Bi or V in BiVO4 crystal because the specific feature of experimental spectra are inconsistent with simulated spectra, which is corresponded to XRD results indicating the formation of Mn-based oxide structures with various oxidation states. [ABSTRACT FROM AUTHOR]

A straightforward, high-yield route was followed to produce visible light active BiVO 4 (BV)-based catalysts through the novel, green approaches: metathesis and metathesis-assisted molten salts. The catalysts prepared at room temperature (BV-RT) and 350 °C for 12 h (BV350/12) exhibited spherical-like and highly crystalline plate-like particles, respectively. A novel BV catalyst was prepared by adding graphite oxide, GO/BV. The synthesis conditions affected crystallite size, crystallinity, optical edge, energy gap, specific area characteristics, and photocatalytic activity. GO/BV achieved 100% rhodamine B (RhB) degradation irradiated (300 min) with low-power blue LEDs. The initial reaction rate (-r 0) of RhB using the GO/BV was 4.57, 3.42 and 1.31-fold faster than BV-RT, BV350/12, and BV350/2. Catalyst dosage and RhB initial concentration on the photoactivity of GO/BV were analyzed. Trapping experiments established that holes and hydroxyl radicals are the main oxidative species causing RhB degradation, and the mechanism was postulated based on GO/BV. Reusability tests confirmed GO/BV chemical stability. GO/BV reached 74% photodegradation of methylene blue (MB). The photodegradation of the RhB + MB mixture using GO/BV showed that the coexistence of MB diminished the RhB degradation to 86%. • A novel, green route was applied to prepare nanostructured BiVO 4 photocatalysts. • Low power blue LEDs were used as effective irradiation source. • BV350/2 h and GO/BV achieved RhB photodegradation of 96 and 100% within 300 min. • GO/BV photocatalytic performance showed 74% MB degradation. • RhB + MB photodegradation over GO/BV showed higher activity towards MB than RhB. [ABSTRACT FROM AUTHOR]

We report a photoelectrochemical investigation of BiVO4 photoanodes prepared by successive ionic layer adsorption and reaction (SILAR), a facile method that yields uniform nanoporous films. After characterization of the phase, morphology, composition, and optical properties of the prepared films, the efficiencies of charge separation (ηsep) and water oxidation (ηox) in solar water splitting cells employing these photoanodes were estimated following a previously reported procedure. Unexpected wavelength and illumination direction dependencies were discovered in the derived efficiencies, casting doubt on the validity of the analysis. An alternative approach using a diffusion–reaction model that explicitly considers the efficiency of electron collection resolved the discrepancies and explained the illumination direction dependence of the photocurrent. Electron diffusion lengths (Ln) of 0.45 μm and 0.55 μm were derived for pristine and cobalt phosphate (Co-Pi) modified BiVO4, respectively, which are much shorter than the film thickness of ~2.1 μm. The Co-Pi treatment also increased ηoxfrom 0.86 to ~1, which is the main reason for the overall performance enhancement caused by adding Co-Pi. These findings suggest that there is little scope for improving the performance of SILAR-deposited BiVO4 photoanodes by further catalyzing water oxidation, but enhanced performance is achievable if electron transport can be improved.

A sensitive and selective label-free photoelectrochemical (PEC) immunosensor was designed for the detection of cardiac troponin I (cTnI). The platform was based on a fluorine-doped tin oxide (FTO)-coated glass photoelectrode modified with bismuth vanadate (BiVO4) and sensitized by an electrodeposited bismuth sulfide (Bi2S3) film. The PEC response of the Bi2S3/BiVO4/FTO platform for the ascorbic acid (AA) donor molecule was approximately 1.6-fold higher than the response observed in the absence of Bi2S3. The cTnI antibodies (anti-cTnI) were immobilized on the Bi2S3/BiVO4/FTO platform surface to produce the anti-cTnI/Bi2S3/BiVO4/FTO immunosensor, which was incubated in cTnI solution to inhibit the AA photocurrent. The photocurrent obtained by the proposed immunosensor presented a linear relationship with the logarithm of the cTnI concentration, ranging from 1 pg mL−1 to 1000 ng mL−1. The immunosensor was successfully employed in artificial blood plasma samples for the detection of cTnI, with recovery values ranging from 98.0% to 98.5%.

The photoelectrochemical (PEC) dual-electron pathway for water oxidation to produce hydrogen peroxide (H 2 O 2 ) shows promising prospects. However, the dominance of the four-electron pathway leading to O 2 evolution competes with this reaction, severely limiting the efficiency of H 2 O 2 production. Here, we report a In 2 O 3 passivator-coated BiVO 4 (BVO) photoanode, which effectively enhances the selectivity and yield of H 2 O 2 production via PEC water oxidation. Based on XPS spectra and DFT calculations, a heterojunction is formed between In 2 O 3 and BVO, promoting the effective separation of interface and surface charges. More importantly, Mott-Schottky analysis and open-circuit potential measurements demonstrate that the In 2 O 3 passivation layer on the BVO photoanode shifts the hole quasi-Fermi level towards the anodic direction, enhancing the oxidation level of holes. Additionally, the widening of the depletion layer and the flattening of the band bending on the In 2 O 3 -coated BVO photoanode favor the generation of H 2 O 2 while suppressing the competitive O 2 evolution reaction. In addition, the coating of In 2 O 3 can also inhibit the decomposition of H 2 O 2 and improve the stability of the photoanode. This work provides new perspectives on regulating PEC two/four-electron transfer for selective H 2 O 2 production via water oxidation., (© 2024 Wiley-VCH GmbH.)

Bismuth vanadate (BiVO 4 ) is regarded as a promising photoanode candidate for photoelectrochemical (PEC) water splitting, but is limited by low efficiency of charge carrier transport and short carrier diffusion length. In this work, we report a strategy comprised of the gradient doping of W and back-to-back stacking of transparent photoelectrodes, where the 3-2 wt.% W gradient doping enhances charge carrier transport by optimizing the band bending degree and back-to-back stack configuration shortens carrier diffusion length without much sacrifice of photons. As a result, the photocurrent density of 3-2 % W:BiVO 4 photoanode reaches 2.20 mA cm -2 at 1.23 V vs. hydrogen electrode (RHE) with a charge transport efficiency of 76.1 % under AM 1.5 G illumination, and the back-to-back stacked 3-2 % W:BiVO 4 photoanodes achieves a photocurrent of 4.63 mA cm -2 after loading Co-Pi catalyst and anti-reflective coating under AM 1.5 G illumination, with long-term stability of 10 hours., (© 2024 Wiley-VCH GmbH.)

Bismuth vanadate (BVO) having suitable band edges is one of the effective photocatalysts for water oxidation, which is the rate-determining step in the water splitting process. Incorporating cocatalysts can reduce activation energy, create hole sinks, and improve photocatalytic ability of BVO. In this work, the visible light active nickel tellurium oxide (NTO) is used as the cocatalyst on the BVO photoanode to improve photocatalytic properties. Different NTO amounts are deposited on the BVO to balance optical and electrical contributions. Higher visible light absorbance and effective charge cascades are developed in the NTO and BVO composite (NTO/BVO). The highest photocurrent density of 6.05 mA/cm 2 at 1.23 V versus reversible hydrogen electrode (V RHE ) and the largest applied bias photon-to-current efficiency (ABPE) of 2.13% are achieved for NTO/BVO, while BVO shows a photocurrent density of 4.19 mA/cm 2 at 1.23 V RHE and ABPE of 1.54%. Excellent long-term stability under light illumination is obtained for NTO/BVO with photocurrent retention of 91.31% after 10,000 s. The photoelectrochemical catalytic mechanism of NTO/BVO is also proposed based on measured band structures and possible interactions between NTO and BVO. This work has depicted a novel cocatalytic BVO system with a new photocharging material and successfully achieves high photocurrent densities for catalyzing water oxidation.

Wide operation temperature is the crucial objective for an energy storage system that can be applied under harsh environmental conditions. For lithium-sulfur batteries, the "shuttle effect" of polysulfide intermediates will aggravate with the temperature increasing, while the reaction kinetics decreases sharply as the temperature decreasing. In particular, sulfur reaction mechanism at low temperatures seems to be quite different from that at room temperature. Here, through in situ Raman and electrochemical impedance spectroscopy studies, the newly emerged platform at cryogenic temperature corresponds to the reduction process of Li 2 S 8 to Li 2 S 4 , which will be another rate-determining step of sulfur conversion reaction, in addition to the solid-phase conversion process of Li 2 S 4 to Li 2 S 2 /Li 2 S at low temperatures. Porous bismuth vanadate (BiVO 4 ) spheres are designed as sulfur host material, which achieve the rapid snap-transfer-catalytic process by shortening lithium-ion transport pathway and accelerating the targeted rate-determining steps. Such promoting effect greatly inhibits severe "shuttle effect" at high temperatures and simultaneously improves sulfur conversion efficiency in the cryogenic environment. The cell with the porous BiVO 4 spheres as the host exhibits excellent rate capability and cycle performance under wide working temperatures., (© 2024 Wiley‐VCH GmbH.)

The thermal transformation of the tetragonal-zircon (tz-) to tetragonal-scheelite (ts-)BiVO 4 was studied by in situ synchrotron X-ray diffraction, thermogravimetric analysis, and Fourier-transformed infrared spectroscopy. Upon heating, the tetragonal zircon polymorph of BiVO 4 (tz-BiVO 4 ) transitioned to the ts-polymorph between 693-773 K. Above 773 K, single phase ts-BiVO 4 was observed before transitioning to the monoclinic fergusonite (mf-) polymorph upon cooling. An anomaly in thermal expansion was observed between 400-500 K, associated with the loss of intercalated H 2 O/NH 4 + from the coprecipitation procedure. Heating tz-BiVO 4 resulted in contraction of the V-O bond distance and VO 4 polyhedra volume, ascribed to rotation of the tetrahedra groups. Attempts to study this by neutron diffraction failed due to the large incoherent scatter from the hydrogenous species. Efforts to remove these species while maintaining the tz-BiVO 4 structure were unsuccessful, suggesting they play a role in stabilizing the tz-polymorph. The local structure of both mf-BiVO4 and tz-BiVO4 were investigated by X-ray pair distribution function analysis, revealing local distortions., (© 2024 The Authors. Chemistry - An Asian Journal published by Wiley-VCH GmbH.)

In this paper, the bismuth vanadate and the composite of bismuth vanadate BiVO4 with nickel ferrite BiVO4/NiFe2O4 is aimed to be synthesized using hydrothermal method for the effective degradation of methylene blue. The concentration of nickel ferrite is varied from 1 to 5%. The morphological, structural, and the optical properties of the prepared samples are studied using X-ray diffraction (XRD), Scanning electron microscope (SEM), Photoluminescence (PL) spectroscopy, and Ultra-violet (UV) spectroscopy. The photocatalytic activity of the prepared photocatalyst is performed under visible light. The composite of BiVO4/NiFe2O4 4% efficiently degrade 99% of methylene blue after 90 min from 100-ml solution under visible light. This paper explains the synthesis of bismuth vanadate and it is composite with nickel ferrite BiVO4/NiFe2O4 and give information about the structural and morphological of these synthesized materials. [ABSTRACT FROM AUTHOR]

As global warming caused by the greenhouse effect is becoming one of the major issues of the 21st century, hydrogen as an alternative to fossil‐based fuels and other energy carriers has gained importance in current research. One promising approach to produce hydrogen is photoelectrochemical water splitting, which uses solar energy combined with suitable semiconducting photoabsorber electrodes to generate hydrogen and oxygen from water. However, most water splitting applications reported to date suffer from degradation of the photoabsorber, resulting in a loss of activity after just a few seconds or minutes. Here, a new approach using conformal ultra‐thin and oxidation‐stable protective layers is presented on Mo:BiVO4 thin films combined with a thin Fe0.1Ni0.9O water oxidation co‐catalyst, applied by electrochemical deposition, to achieve unprecedented photocurrent densities of up to 5.6 mA cm−2 under simulated AM1.5G illumination and a neutral pH while providing more stable electrodes for water oxidation. [ABSTRACT FROM AUTHOR]

As global warming caused by the greenhouse effect is becoming one of the major issues of the 21st century, hydrogen as an alternative to fossil‐based fuels and other energy carriers has gained importance in current research. One promising approach to produce hydrogen is photoelectrochemical water splitting, which uses solar energy combined with suitable semiconducting photoabsorber electrodes to generate hydrogen and oxygen from water. However, most water splitting applications reported to date suffer from degradation of the photoabsorber, resulting in a loss of activity after just a few seconds or minutes. Here, a new approach using conformal ultra‐thin and oxidation‐stable protective layers is presented on Mo:BiVO4 thin films combined with a thin Fe0.1Ni0.9O water oxidation co‐catalyst, applied by electrochemical deposition, to achieve unprecedented photocurrent densities of up to 5.6 mA cm−2 under simulated AM1.5G illumination and a neutral pH while providing more stable electrodes for water oxidation. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) as cocatalyst for photoelectrochemical (PEC) water splitting is promising but still in its infancy due to the challenge to fabricate high‐quality MOFs coated photoelectrodes. Herein, a successive ionic layer adsorption and reaction (SILAR) method is used to fabricate high‐quality conformal and ultrathin MOFs overlayer with preferred orientation on nanoporous BiVO4 films. 20 molecular monolayers of Co‐MOF coated BiVO4 photoanodes exhibit 3.1‐folds of photocurrent density in comparison with pristine BiVO4. The onset potential shows a negative shift of 320 mV. To further demonstrate the extensibility of SILAR method, the alternative Co‐MOF and Ni‐MOF coated BiVO4 photoanodes deliver an enhanced photocurrent density of 2.97 mA cm−2. The PEC performance achieved rivals the reported results of BiVO4 and MOF hybrid photoanodes. The PEC improvements should be attributed to the high‐quality conformal and ultrathin MOFs overlayer, which can efficiently passivate the surface states of BiVO4, and accelerate the hole transfer through Co‐MOF layer. Three critical roles of Co‐MOF overlayer are elaborately revealed. In contrast, hydrothermally prepared BiVO4/Co‐MOF photoanodes possess inferior PEC performance, such as the photocurrent, and stability. This work clearly demonstrates SILAR method is a simple and efficient approach to realize conformal and ultrathin MOF coating with high‐quality. [ABSTRACT FROM AUTHOR]

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Bismuth vanadate (BiVO4) has attracted substantial attention on account of its usefulness in producing hydrogen by photoelectrochemical (PEC) water splitting. The exploitation of BiVO4 for this purpose is yet limited by severe charge recombination in the bulk of BiVO4, which is caused by the short diffusion length of the photoexcited charge carriers and inefficient charge separation. Enormous effort has been made to improve the photocurrent density and solar-to-hydrogen conversion efficiency of BiVO4. This study demonstrates that modulating the composition of the electrode and the electronic configuration of BiVO4 by decoration with silver nanoparticles (Ag NPs) is effective in not only enhancing the charge carrier concentration but also suppressing charge recombination in the solar water splitting process. Decoration with a small number of Ag NPs significantly enhances the photocurrent density of BiVO4 to an extent that increases with the concentration of the Ag NPs. At 0.5% Ag NPs, the photocurrent density approaches 4.1 mA cm−2 at 1.23 V versus a reversible hydrogen electrode (RHE) under solar simulated light illumination; this value is much higher than the 2.3 mA cm−2 of pure BiVO4 under the same conditions. X-ray absorption spectroscopy (XAS) is utilized to investigate the electronic structure of pure BiVO4 and its modification by decoration with Ag NPs. Analytical results indicate that increased distortion of the VO4 tetrahedra alters the V 3d–O 2p hybridized states. Additionally, as the Ag concentration increases, the oxygen vacancy defects that act as recombination centers in BiVO4 are reduced. In situ XAS, which is conducted under dark and solar illumination conditions, reveals that the significantly enhanced PEC performance is attributable to the synergy of modulated atomic/electronic structures and the localized surface plasmon resonance effect of the Ag nanoparticles.

A polymetallic oxide cocatalyst (Mo-MnO y /FeCoNiO x) with well-defined electronic and catalytic properties is designed on BiVO 4 photoelectrode for highly efficient and stable photoelectrocatalytic water oxidation. [Display omitted] • A cocatalyst enables BiVO 4 photoelectrode with a high density in long test. • The dual-layer cocatalyst can boost the photogenerated charge transfer. • Mo sites activate the Mn sites instead of directly serving as the catalytic center. The rate-determining oxygen evolution reaction (OER) always limits the high-efficient conversion of solar energy to green hydrogen fuels through photoelectrocatalytic or photocatalytic water splitting. The high catalytic overpotential and the instability of catalytic center are commonly regarded as the primary factors contributing to the low rate of OER, remaining to be a challenge in the field of water splitting. Herein, a polymetallic oxide cocatalyst (Mo-MnO y /FeCoNiO x) with well-defined electronic and catalytic properties is designed on BiVO 4 photoelectrode for highly efficient and stable photoelectrocatalytic water oxidation. The experimental characterization demonstrates that the dual-layer design of Mo-MnO y /FeCoNiO x can significantly optimizes the electronic property of MnO y and FeCoNiO x components, boosting the photogenerated charge transfer between Mo-MnO y /FeCoNiO x cocatalyst and BiVO 4 photoelectrode. The density functional theory (DFT) simulation reveals that the Mo sites in Mo-MnO y layer can activate the neighboring surface Mn sites instead of directly serving as the catalytic center, thereby establishing these Mn sites as primary active centers for achieving stable OER. The developed Mo-MnO y /FeCoNiO x /BiVO 4 photoelectrode exhibits a current density of 6.18 mA cm−2 with an excellent stability for 30 h at 1.23 V RHE under 1 sun irradiation, exhibiting the excellent activity and durability. This work sheds light on design of high-performance multiple-component water-oxidation cocatalyst on photoanode. [ABSTRACT FROM AUTHOR]

Photoelectrochemical water splitting with bismuth vanadate (BiVO 4) photoanodes is a promising strategy for solar-driven hydrogen production. However, the unfavorable interfacial charge behavior causes severe charge recombination and photocorrosion issue of BiVO 4. Herein, cobalt-doped carbon nanodots (CoCDs) are employed for efficient charge extraction due to Co impurity level, which form band alignment with BiVO 4 , as well as accelerate surface reaction. As a result, the obtained CoCDs/BVO photoanode demonstrates an outstanding photocurrent density of 5.26 mA/cm2 at 1.23 V vs. reversible hydrogen electrode under AM 1.5 G illumination, superior to most BiVO 4 photoanodes with cocatalysts. Carbon nanodots turn out to be an excellent matrix to activate and stabilize Co atoms and tightly anchor onto BiVO 4 , which makes them good interfacial modifier. This work paves an avenue for the optimization of semiconductor/liquid interface and the application of carbon nanomaterials in photoelectrodes. [Display omitted] • Carbon nanodots with high dispersity, favorable band structure and catalysis capability are obtained by cobalt doping. • Cobalt-doped carbon nanodots (CoCDs) are developed as an efficient surface modifier for BiVO 4 photoanodes (BVO). • CoCDs form good band alignment with BVO and promote surface charge transfer efficiency to nearly 100%. • The CoCDs/BVO photoanode demonstrates a high photocurrent density of 5.26 mA/cm2 at 1.23 V RHE under AM 1.5 G illumination. [ABSTRACT FROM AUTHOR]

Abstract Biosynthesis of bismuth vanadate (BiVO4) nanorods was performed using dried fruit extracts of Hyphaene thebaica as a cost effective reducing and stabilizing agent. XRD, DRS, FTIR, zeta potential, Raman, HR-SEM, HR-TEM, EDS and SAED were used to study the main physical properties while the biological properties were established by performing diverse assays. The zeta potential is reported as − 5.21 mV. FTIR indicated Bi–O and V–O vibrations at 640 cm−1 and 700 cm−1/1120 cm−1. Characteristic Raman modes were observed at 166 cm−1, 325 cm−1 and 787 cm−1. High resolution scanning and transmission electron micrographs revealed a rod like morphology of the BiVO4. Bacillus subtilis, Klebsiella pneumonia, Fusarium solani indicated highest susceptibility to the different doses of BiVO4 nanorods. Significant protein kinase inhibition is reported for BiVO4 nanorods which suggests their potential anticancer properties. The nanorods revealed good DPPH free radical scavenging potential (48%) at 400 µg/mL while total antioxidant capacity of 59.8 µg AAE/mg was revealed at 400 µg/mL. No antiviral activity is reported on sabin like polio virus. Overall excellent biological properties are reported. We have shown that green synthesis can replace well established processes for synthesizing BiVO4 nanorods.