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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/cm2 at 1.23 V versus reversible hydrogen electrode (VRHE) 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/cm2 at 1.23 VRHE 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.

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Background MXene is a newly discovered substance consisting of 2D transition metal carbides or nitrides, produced through the disintegration and etching of aluminum layers. It possesses numerous properties, including a high surface area, conductivity, strength, stiffness, negative zeta potential, and excellent volumetric capacitance. MXene is utilized in detecting anti-cancer medicine, while bismuth vanadate (BiVO4) is synthesized to form an optimized material for anti-cancer activity applications. BiVO4 exhibits visible light absorption, strong chemical stability, and non-toxic properties. However, when loaded onto target stem cells, it can cause skin and respiratory irritation. Aim This study aimed to evaluate the facile fabrication of titanium carbide (Ti3C2)-BiVO4 nanomaterials coupled with oxides for anti-cancer activity. Moreover, it aimed to create Ti3C2-BiVO4 nanomaterials in combination with oxides using X-ray diffraction (XRD) and scanning electron microscopy (SEM) to assess their potential as efficient and targeted anti-cancer agents. Methods and materials To prepare the 2D Ti3C2 MXene, 2.5 g of titanium aluminum carbide (Ti3AlC2) powder was dissolved in 60 mL of a 40% hydrofluoric acid (HF) solution in a polytetrafluoroethylene(PTFE) container. The etching process was made more efficient and completed in 24 hours by using a magnetic stirring system to keep the mixture stirred and heated continuously. The centrifugation was performed at 4000 rpm for five minutes. Subsequently, deionized water was used to wash the solution many times until its pH reached around 7. The appropriate Ti3C2 powder was made by vacuum drying the acquired sediment at 80°C for 24 hours. Monoclinic BiVO4 samples were synthesized via a hydrothermal method. Typically, 10 mmol of Bi(NO3)3.5H2O was dissolved in 100 mL of a 2 mol/L HNO3 solution and stirred uniformly. Subsequently, 10 mmol of ammonium metavanadate (NH4VO3) was added to the mixed solution. After being stirred for one hour, the mixture was transferred into a 100 mL sealed Teflon-lined stainless steel autoclave at 180°C for 16 hours. After cooling to room temperature, the sediment was washed three times with deionized water, ethanol, and acetone, respectively. Finally, the suspension was dried at 80°C, followed by calcination at 450°C for three hours to obtain BiVO4. Ti3C2-BiVO4 heterostructures were prepared by surface modification Ti3C2 using BiVO4 suspensions by a simple, cost-effective approach. Results Ti3C2 nanosheets were observed with BiVO4 particles, and the high crystalline nature of the compound was confirmed after XRD analysis and energy-dispersive spectroscopy (EDS) analysis. The compound was found to be pure without any impurities and exhibited anti-cancer activity. Conclusion The XRD, field emission scanning electron microscopy(FESEM), and EDS investigations provide an in-depth analysis of the structural, morphological, and compositional characteristics of Ti3C2-BiVO4 sheets. The XRD analysis proves the successful combination of different materials and the presence of crystalline phases. The FESEM imaging technique exposes the shape and arrangement of particles in sheets, while the EDS analysis verifies the elemental composition and uniform distribution. These investigations show that Ti3C2-BiVO4 composites have been successfully synthesized, indicating their potential for use in anti-cancer applications.

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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 Li2S8 to Li2S4, which will be another rate-determining step of sulfur conversion reaction, in addition to the solid-phase conversion process of Li2S4 to Li2S2/Li2S at low temperatures. Porous bismuth vanadate (BiVO4) 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 BiVO4 spheres as the host exhibits excellent rate capability and cycle performance under wide working temperatures.

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Herein, we propose a simple and effective fluoride (F-) ions post-treatment method to improve the solar water splitting performance of monoclinic BiVO4 (abbreviated as BVO). The surface modification of BVO with functional F- ions not only facilitates the transfer and separation efficiency of carriers at the electrode/electrolyte interface but also promotes the adsorption and activation of water, resulting in a photocurrent of 3.2 mA/cm2 at a bias voltage of 1.2 VRHE. Furthermore, the transfer and separation of carriers in the bulk and on the surface are further regulated by the oxygen vacancies induced by F- ions, thereby enhancing the PEC water splitting performance of BVO. Notably, the experimental findings demonstrate that the introduce of F- ions into the KBi electrolyte enhances the photo-charging process of BVO. Specifically, at a bias voltage of 0.6 VRHE, the BVO-0.12F sample exhibits a stable photocurrent of 1.2 mA/cm2, which is twice as high as that of the initial BVO sample. Remarkably, our study unveils that the addition of F- ions into the KBi electrolyte solution plays a pivotal role in facilitating the separation of charge carriers and promoting interfacial charge transport. Consequently, this further leads to a substantial enhancement in the solar water splitting performance for BVO-0.12F photoanode.

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The thermal transformation of the tetragonal-zircon (tz-) to tetragonal-scheelite (ts-)BiVO4 was studied by in situ synchrotron X-ray diffraction, thermogravimetric analysis, and Fourier-transformed infrared spectroscopy. Upon heating, the tetragonal zircon polymorph of BiVO4 (tz-BiVO4) transitioned to the ts-polymorph between 693-773 K. Above 773 K, single phase ts-BiVO4 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 H2O/NH4 + from the coprecipitation procedure. Heating tz-BiVO4 resulted in contraction of the V-O bond distance and VO4 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-BiVO4 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.

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Formaldehyde (HCHO) is one of the primary indoor air pollutants, and efficiently eliminating it, especially at low concentrations, remains challenging. In this study, BiVO4-TiO2 catalyst was developed using ultrasonic blending technology for the photocatalytic oxidation of low-level indoor HCHO. The crystal structure, surface morphology, element distribution, and active oxidation species of the catalyst were examined using XRD, SEM, TEM, UV-Vis, EDS, and ESR techniques. Our results demonstrated that the BiVO4-TiO2 catalyst, prepared by ultrasonic blending, exhibited good oxidation performance and stability. The HCHO concentration reduced from 1.050 to 0.030 mg/m3 within 48 h, achieving a removal rate of 97.1%. The synergy between BiVO4 and TiO2 enhanced the efficiency of separating photogenerated carriers and minimized the likelihood of recombination between photogenerated electrons and holes. Additionally, this synergy significantly enhanced the presence of hydroxyl radicals (·OH) on the catalyst, resulting in an oxidation performance superior to that of either BiVO4 or TiO2. Our research offers valuable insights for the development of new photocatalysts to address HCHO pollution.

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Strong metal-support interaction (SMSI) is widely proposed as a key factor in tuning catalytic performances. Herein, the classical SMSI between Au nanoparticles (NPs) and BiVO4 (BVO) supports (Au/BVO-SMSI) is discovered and used innovatively for photoelectrochemical (PEC) water splitting. Owing to the SMSI, the electrons transfer from V4+ to Au NPs, leading to the formation of electron-rich Au species (Auδ-) and strong electronic interaction (i.e., Auδ--Ov-V4+), which readily contributes to extract photogenerated holes and promote charge separation. Benefitted from the SMSI effect, the as-prepared Au/BVO-SMSI photoanode exhibits a superior photocurrent density of 6.25 mA cm-2 at 1.23 V versus the reversible hydrogen electrode after the deposition of FeOOH/NiOOH cocatalysts. This work provides a pioneering view for extending SMSI effect to bimetal oxide supports for PEC water splitting, and guides the interfacial electronic and geometric structure modulation of photoanodes consisting of metal NPs and reducible oxides for improved solar energy conversion efficiency.

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In order to expand the application of bismuth vanadate (BiVO4) to the field of photoelectrochemistry, researchers have explored the potential of BiVO4 in catalyzing or degrading organic substances, potentially presenting a green and eco-friendly solution. A study was conducted to investigate the impact of electrolytes on the photocatalysis of benzyl alcohol by BiVO4. The research discovered that, in an acetonitrile electrolyte (pH 9) with sodium bicarbonate, BiVO4 catalyzed benzyl alcohol by introducing saturated V5+. This innovation addressed the issue of benzyl alcohol being susceptible to catalysis in an alkaline setting, as V5+ was prone to dissolution in pH 9 on BiVO4. The concern of the photocorrosion of BiVO4 was mitigated through two approaches. Firstly, the incorporation of a non-aqueous medium inhibited the formation of active material intermediates, reducing the susceptibility of the electrode surface to photocorrosion. Secondly, the presence of saturated V5+ further deterred the leaching of V5+. Concurrently, the production of carbonate radicals by bicarbonate played a vital role in catalyzing benzyl alcohol. The results show that, in this system, BiVO4 has the potential to oxidize benzyl alcohol by photocatalysis.

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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 BiVO4/CoP or CdS/NiO photoanodes for nitrogenase activation toward N2 fixation. The constructed PBEC based on BiVO4/CoP photoanode requires minimal external bias (200 mV) and suppresses O2 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.

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Atomically precise metal nanoclusters (NCs) present new opportunities for creating innovative solar-powered photoanodes due to their extraordinary physicochemical properties. Nevertheless, ultrasmall metal NCs tend to aggregate and lack active sites under light irradiation, which severely limits their widespread application. We have developed a strategy to design efficient ternary photoanodes by successively modifying AgAu NCs and CoNi-LDH on BiVO4 substrates using versatile impregnation and electrodeposition. The electronic properties of AgAu NCs facilitate the rapid transfer of photogenerated carriers on BiVO4 and CoNi-LDH. Additionally, ultrathin CoNi-LDH acts as a hole-collecting layer, which quickly extracts holes to the electrode/electrolyte interface. The synergistic effect and the matched energy levels between the ternary heterostructures promote the OER process, which significantly improved the photoelectrochemical (PEC) water oxidation performance. This study presents a new idea for further exploration of metal nanocluster-based PEC systems.

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The most challenging obstacle for photocatalysts to efficiently harvest solar energy is the sluggish surface redox reaction (e. g., oxygen evolution reaction, OER) kinetics, which is believed to originate from interface catalysis rather than the semiconductor photophysics. In this work, we developed a light-modulated transient photocurrent (LMTPC) method for investigating surface charge accumulation and reaction on the W-doped bismuth vanadate (W : BiVO4) photoanodes during photoelectrochemical water oxidation. Under illuminating conditions, the steady photocurrent corresponds to the charge transfer rate/kinetics, while the integration of photocurrent (I~t) spikes during the dark period is regarded as the charge density under illumination. Quantitative analysis of the surface hole densities and photocurrents at 0.6 V vs. reversible hydrogen electrode results in an interesting rate-law kinetics switch: a 3rd-order charge reaction behavior appeared on W : BiVO4, but a 2nd-order charge reaction occurred on W : BiVO4 surface modified with ultrathin Bi metal-organic-framework (Bi-MOF). Consequently, the photocurrent for water oxidation on W : BiVO4/Bi-MOF displayed a 50 % increment. The reaction kinetics alternation with new interface reconstruction is proposed for new mechanism understanding and/or high-performance photocatalytic applications.

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Rechargeable aqueous zinc ion batteries (ZIBs) have emerged as a promising alternative to lithium-ion batteries due to their inherent safety, abundant availability, environmental friendliness and cost-effectiveness. However, the cathodes in ZIBs encounter challenges such as structural instability, low capacity, and sluggish kinetics. In this study, we constructed BiVO4@VO2 (BVO@VO) heterojunction cathode material with bismuth vanadate and vanadium dioxide phases for ZIBs, which demonstrate significant advancements in both aqueous and quasi-solid-state ZIBs. Benefitting from the heterojunction structure, the materials present a high capacity of 262 mAh g-1 at 0.1 A g-1, superb cyclic stability with 96% capacity retention after 1000 cycles at 2 A g-1, and outstanding rate property with a specific capacity of 218 mAh g-1 even at a high rate of 5.0 A g-1. Furthermore, the flexible quasi-solid-state ZIBs incorporating the BVO@VO cathode demonstrate prolonged cyclic life performance with a remarkable specific capacity of 234 mAh g-1 over 100 cycles at a current density of 0.1 A g-1. This study potentially paves the way for the utilization of heterointerface-enhanced zinc ion diffusion for vanadium-based materials in ZIBs, thereby providing a new approach for the design and investigation of high-performance zinc-ion systems.

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In this work, a surface dispersed heterojunction of BiVO4-nanoparticle@WO3-nanoflake was successfully prepared by hydrothermal combined with solvothermal method. We optimized the morphology of the WO3 nanoflakes and BiVO4 nanoparticles by controlling the synthesis conditions to get the uniform BiVO4 loaded on the surface of WO3 arrays. The phase composition and morphology evolution with different reaction precursors were investigated in detail. When used as photoanodes, the WO3/BiVO4 composite exhibits superior activity with photocurrent at 3.53 mA cm-2 for photoelectrochemical (PEC) water oxidation, which is twice that of pure WO3 photoanode. The superior surface dispersion structure of the BiVO4-nanoparticle@WO3-nanoflake heterojunction ensures a large effective heterojunction area and relieves the interfacial hole accumulation at the same time, which contributes to the improved photocurrents together with the stability of the WO3/BiVO4 photoanodes.

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Photoelectrochemical (PEC) water splitting represents an attractive strategy to realize the conversion from solar energy to hydrogen energy, but severe charge recombination in photoanodes significantly limits the conversion efficiency. Herein, a unique BiVO4 (BVO) nanobowl (NB) heterojunction photoanode, which consists of [001]-oriented BiOCl underlayer and BVO nanobowls containing embedded BiOCl nanocrystals, is fabricated by nanosphere lithography followed by in situ transformation. Experimental characterizations and theoretical simulation prove that nanobowl morphology can effectively enhance light absorption while reducing carrier diffusion path. Density functional theory (DFT) calculations show the tendency of electron transfer from BVO to BiOCl. The [001]-oriented BiOCl underlayer forms a compact type II heterojunction with the BVO, favoring electron transfer from BVO through BiOCl to the substrate. Furthermore, the embedded BiOCl nanoparticles form a bulk heterojunction to facilitate bulk electron transfer. Consequently, the dual heterojunctions engineered BVO/BiOCl NB photoanode exhibits attractive PEC performance toward water oxidation with an excellent bulk charge separation efficiency of 95.5%, and a remarkable photocurrent density of 3.38 mA cm-2 at 1.23 V versus reversible hydrogen electrode, a fourfold enhancement compared to the flat BVO counterpart. This work highlights the great potential of integrating dual heterojunctions engineering and morphology engineering in fabricating high-performance photoelectrodes toward efficient solar conversion.

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Regulating the interfacial charge transfer behavior between cocatalysts and semiconductors remains a critical challenge for attaining efficient photoelectrochemical water oxidation reactions. Herein, using bismuth vanadate (BiVO4 ) photoanode as a model, it introduces an Au binding bridge as holes transfer channels onto the surfaces of BiVO4 , and the cyano-functionalized cobalt cubane (Co4 O4 ) molecules are preferentially immobilized on the Au bridge due to the strong adsorption of cyano groups with Au nanoparticles. This orchestrated arrangement facilitates the seamless transfer of photogenerated holes from BiVO4 to Co4 O4 molecules, forming an orderly charge transfer pathway connecting the light-absorbing layer to reactive sites. An exciting photocurrent density of 5.06 mA cm-2 at 1.23 V versus the reversible hydrogen electrode (3.4 times that of BiVO4 ) is obtained by the Co4 O4 @Au(A)/BiVO4 photoanode, where the surface charge recombination is almost completely suppressed accompanied by a surface charge transfer efficiency over 95%. This work represents a promising strategy for accelerating interfacial charge transfer and achieving efficient photoelectrochemical water oxidation reaction.

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High-efficient photoelectrocatalytic direct ammonia oxidation reaction (AOR) conducted on semiconductor photoanodes remains a substantial challenge. Herein, we develop a strategy of simply introducing ppm levels of Cu ions (0.5-10 mg/L) into NH3 solutions to significantly improve the AOR photocurrent of bare BiVO4 photoanodes from 3.4 to 6.3 mA cm-2 at 1.23 VRHE , being close to the theoretical maximum photocurrent of BiVO4 (7.5 mA cm-2 ). The surface charge-separation efficiency has reached 90 % under a low bias of 0.8 VRHE . This AOR exhibits a high Faradaic efficiency (FE) of 93.8 % with the water oxidation reaction (WOR) being greatly suppressed. N2 is the main AOR product with FEs of 71.1 % in aqueous solutions and FEs of 100 % in non-aqueous solutions. Through mechanistic studies, we find that the formation of Cu-NH3 complexes possesses preferential adsorption on BiVO4 surfaces and efficiently competes with WOR. Meanwhile, the cooperation of BiVO4 surface effect and Cu-induced coordination effect activates N-H bonds and accelerates the first rate-limiting proton-coupled electron transfer for AOR. This simple strategy is further extended to other photoanodes and electrocatalysts.

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Photocatalytic degradation of chlorinated persistent organic pollutants is a very challenging process due to the high redox potential of the C-Cl bond that requires wide band gap catalysts that are activated under UV light. Designing a Z-scheme heterojunction between visible light-activated metal oxides with compatible band gaps enables these redox potentials. Herein, we report the design of a pyrochlore/Aurivillius Z-scheme heterojunction to enhance the photocatalytic activity of BiVO4 for the degradation of trichloroethylene. We prepared Bi2Ru2O7/BiVO4 heterostructured photocatalysts by a controlled hydrothermal approach. Upon optimizing the Bi2Ru2O7 ratio to 1.0 wt %, the heterostructured photocatalyst demonstrated enhanced activity in the degradation of trichloroethylene (TCE) under simulated sunlight irradiation compared to bare BiVO4 and Bi2Ru2O7, respectively. Decorating the surface of the catalyst with palladium nanodomains to create the Pd@Bi2Ru2O7/BiVO4 nanocomposite showed a substantial increase in the photocatalytic degradation of TCE. The material characterization indicated that the architecture of the material provides a synergy of enhancing the redox potential of the photocatalyst and improving the charge carrier dynamics. Furthermore, the photoelectrochemical characterization confirmed that the dual heterojunctions in the Pd@Bi2Ru2O7/BiVO4 nanocomposite resulted in improved interfacial charge carrier transfer and enhanced the electron/hole separation efficiency compared to the nonpalladized catalysts. This work provides a promising approach for band gap engineering of visible light photocatalysts for the degradation of halogenated persistent organic pollutants.

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WO3/BiVO4 heterojunction photoanodes can be efficiently employed in photoelectrochemical (PEC) cells for the conversion of water into molecular oxygen, the kinetic bottleneck of water splitting. Composite WO3/BiVO4 photoelectrodes possessing a nanoflake-like morphology have been synthesized through a multistep process and their PEC performance was investigated in comparison to that of WO3/BiVO4 photoelectrodes displaying a planar surface morphology and similar absorption properties and thickness. PEC tests, also in the presence of a sacrificial hole scavenger, electrochemical impedance analysis under simulated solar irradiation, and incident photon to current efficiency measurements highlighted that charge transport and charge recombination issues affecting the performance of the planar composite can be successfully overcome by nanostructuring the WO3 underlayer in nanoflake-like WO3/BiVO4 heterojunction electrodes.

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We report a photochemical bismuth vanadate (BiVO4 ) sensing material, which possesses a large proportion of (110) and (011) facets combined with the additional (111) facets, for the selective detection of ultra-low concentration hydrogen sulfide (H2 S) driven by visible light. Specifically, the obtained octadecahedron BiVO4 (Octa-BiVO4 ) performs a high response value (67) and short response time (47.4 s) to 100 ppm H2 S with good stability for nearly 100 days, as well as undisturbedness by moist air. With the combination of experimental and theoretical calculation results, the adsorption and carrier transfer behaviors of H2 S molecules on the Octa-BiVO4 crystal surface are investigated. By adjusting the ratio of different crystal facets and controlling the facets with characteristic adsorption, we achieve improved anisotropic photoinduced carrier separation and high selectivity for a specific gas. Furthermore, this facial facet engineering can be extended to the synthesis of other sensing materials, offering huge opportunities for fundamental research and technological applications.

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Bismuth vanadate (BiVO4) is an outstanding photoanode material for photoelectrochemical water splitting. In this work, a series of single crystalline BiVO4 photoanodes are synthesized by pulsed laser deposition (PLD). Once coated with a thin layer of cobalt oxide (CoOx) cocatalyst, also by PLD, the photoanodes support efficient photoelectrochemical generation of chlorine (Cl2) from brine under simulated solar light. The activity of the chlorine generation reaction (ClER) is optimized when the thickness of CoOx is about 3 nm, with the faradic efficiency of ClER exceeding 60%. Detailed studies show that the CoOx cocatalyst layer is amorphous, uniform in thickness, and chemically robust. As such, the cocatalyst also effectively protects the underlying BiVO4 photoanodes against chlorine corrosion. This work provides insights into using artificial photosynthesis for byproducts that carry significant economic value while avoiding the energetically expensive oxygen evolution reactions.