Bi/BiVO4&Bi4V2O11复合催化剂的制备及其光催化性能

经由溶剂热反应、光辅助还原过程制备Bi/Bi VO_4Bi_4V_2O_(11)纳米复合光催化材料。通过X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、高分辨率透射电子显微镜(HRTEM)、X射线光电子能谱(XPS)、紫外-可见漫反射光谱(UV-Vis DRS)、N_2吸附-脱附等温线和光致发光(PL)等手段对该复合物进行表征。实验结果表明当金属Bi与BiVO_4Bi_4V_2O_(11)的质量比值为0.8,可见光照射30 min时,Bi/BiVO_4Bi_4V_2O_(11)复合催化剂对罗丹明B(RhB)的降解率可达95.6%。此外,Bi/BiVO_4Bi_4V_2O_(11)对四环素(TC)的降解也表现出增强的光催化性能。Bi/BiVO_4Bi_4V_2O_(11)复合材料提升的光催化性能可能归因于金属Bi的表面等离子体共振(SPR)效应、拓宽的可见光吸收范围和增大的比表面积。此外,提出了复合光催化剂可能的光催化机理。     

Solar-Assisted eBiorefinery: Photoelectrochemical Pairing of Oxyfunctionalization and Hydrogenation Reactions

Inspired by natural photosynthesis, biocatalytic photoelectrochemical (PEC) platforms are gaining prominence for the conversion of solar energy into useful chemicals by combining redox biocatalysis and photoelectrocatalysis. Herein, we report a dual biocatalytic PEC platform consisting of a molybdenum (Mo)-doped BiVO₄ (Mo:BiVO₄) photoanode and an inverse opal ITO (IO-ITO) cathode that gives rise to the coupling of peroxygenase and ene-reductase-mediated catalysis, respectively. In the PEC cell, the photoexcited electrons generated from the Mo:BiVO₄ are transferred to the IO-ITO and regenerate reduced flavin mononucleotides to drive ene-reductase-catalyzed trans-hydrogenation of ketoisophrone to (R)-levodione. Meanwhile, the photoactivated Mo:BiVO₄ evolves H₂O₂ in situ via a two-electron water-oxidation process with the aid of an applied bias, which simultaneously supplies peroxygenases to drive selective hydroxylation of ethylbenzene into enantiopure (R)-1-phenyl-1-hydroxyethane. Thus, the deliberate integration of PEC systems with redox biocatalytic reactions can simultaneously produce valuable chemicals on both electrodes using solar-powered electrons and water.     

Solar‐Assisted eBiorefinery: Photoelectrochemical Pairing of Oxyfunctionalization and Hydrogenation Reactions

Inspired by natural photosynthesis, biocatalytic photoelectrochemical (PEC) platforms are gaining prominence for the conversion of solar energy into useful chemicals by combining redox biocatalysis and photoelectrocatalysis. Herein, we report a dual biocatalytic PEC platform consisting of a molybdenum (Mo)‐doped BiVO₄ (Mo:BiVO₄) photoanode and an inverse opal ITO (IO‐ITO) cathode that gives rise to the coupling of peroxygenase and ene‐reductase‐mediated catalysis, respectively. In the PEC cell, the photoexcited electrons generated from the Mo:BiVO₄ are transferred to the IO‐ITO and regenerate reduced flavin mononucleotides to drive ene‐reductase‐catalyzed trans‐hydrogenation of ketoisophrone to (R)‐levodione. Meanwhile, the photoactivated Mo:BiVO₄ evolves H₂O₂ in situ via a two‐electron water‐oxidation process with the aid of an applied bias, which simultaneously supplies peroxygenases to drive selective hydroxylation of ethylbenzene into enantiopure (R)‐1‐phenyl‐1‐hydroxyethane. Thus, the deliberate integration of PEC systems with redox biocatalytic reactions can simultaneously produce valuable chemicals on both electrodes using solar‐powered electrons and water.     

Highly Efficient Photoelectrochemical Water Splitting with an Immobilized Molecular Co4O4 Cubane Catalyst

Molecular Co₄O₄ cubane water oxidation catalysts were combined with BiVO₄ electrodes for photoelectrochemical (PEC) water splitting. The results show that tuning the substituent groups on cobalt cubane allows the PEC properties of the final molecular catalyst/BiVO₄ hybrid photoanodes to be tailored. Upon loading a new cubane complex featuring alkoxy carboxylato bridging ligands ( 1 h ) on BiVO₄, an AM 1.5G photocurrent density of 5 mA cm⁻² at 1.23 V vs. RHE for water oxidation was obtained, the highest photocurrent for undoped BiVO₄ photoanodes. A high solar‐energy conversion efficiency of 1.84 % was obtained for the integrated photoanode, a sixfold enhancement over that of unmodified BiVO₄. These results and the high surface charge separation efficiency support the role of surface‐modified molecular catalysts in improving PEC performance and demonstrate the potential of molecule/semiconductor hybrids for efficient artificial photosynthesis.     

AuAg bimetallic nanoparticles film fabricated based on H2O2-mediated silver reduction and its application

A method to fabricate AuAg bimetallic nanoparticles film by H₂O₂-mediated reduction of silver was reported. Gold nanoparticles (Au NPs) were first adsorbed onto the surface of a self-assembled 2-aminoethanethiol monolayer-modified gold film or 3-aminopropyltriethoxysilane (APTES) monolayer-modified quartz slide. Upon further treatment of this modified film with the solution containing silver nitrate (AgNO₃) and H₂O₂, silver was deposited on the surface of Au NPs. The size of the AuAg bimetallic particles could be readily tuned by manipulating the concentration of H₂O₂. Surface plasmon resonance (SPR) was used to investigate the process, the deposition of silver on Au NPs modified gold film resulted in an obvious decrease of depth in the SPR reflectance intensity and minimum angle curves (SPR R-θ curves), which may be utilized for the quantitative SPR detection of the analyte, H₂O₂. Combination of the biocatalytic reaction that could yield H₂O₂ by using the enzyme, glucose oxidase, with the deposition of silver may enable the design of a glucose biosensor by SPR technique. Furthermore, we evaluated the AuAg bimetallic nanoparticles film for their ability to be an effective substrate for surface-enhanced Raman scattering (SERS).     

Ternary non-noble metal chalcogenide (W–Co–Se) as electrocatalyst for oxygen reduction reaction

In this study, a catalyst based on a novel ternary non-noble metal chalcogenide, W–Co–Se, was synthesized for the oxygen reduction reaction (ORR) in acidic medium. The non-noble metal chalcogenide catalyst was electrochemically stable in the potential range of 0.05–0.8 V versus NHE in 0.5 M H₂SO₄ aqueous solution. This catalyst demonstrated significant catalytic activity towards the ORR, showing the ORR onset potential at 0.755 V versus NHE in 0.5 M H₂SO₄ at 25 °C. Such high activity might be attributed to the electronic structure of non-noble metals modified by chalcogen.     

Interfacial coupling of sea urchin-like (Mo4O11-MoS2-VO2) promoted electron redistributions for significantly boosted hydrogen evolution reaction

Developing efficient electrocatalysts for hydrogen evolution reaction (HER) is of great importance in contemporary water electrolysis technology. Here, a novel hierarchically sea urchin-like electrocatalyst (Mo₄O₁₁-MoS₂-VO₂) is synthesized by hydrothermal deposition and post-annealing strategy. The optimized electrocatalyst behaves as a high active hydrogen evolution electrode in 0.5 mol/L H₂SO₄. This electrode needs overpotential of only 43 mV to achieve 10 mA/cm² with a Tafel slope of 37 mV/dec and maintains its catalytic activity for at least 36 h. Better than most previously reported non-noble metal electrocatalysts anchored on carbon cloth. It is worth mentioning that the hierarchical sea urchin-like structure promotes the redistribution of electrons and provides more catalytic active sites. This strategy shows a way for the construction of inexpensive non-noble metal electrocatalysts in the future.     

Probing nanocolumnar silver nanoparticle/zinc oxide hierarchical assemblies with advanced surface plasmon resonance and their enhanced photocatalytic performance for formaldehyde removal

Recent advances in photocatalysis focus on the development of materials with hierarchical structure and on the surface plasmon resonance (SPR) phenomenon exhibited by metal nanoparticles (NPs). In this work, both are combined in a material where size‐controllable Ag‐NPs are uniformly loaded onto the hierarchical microporous and mesoporous and nanocolumnar structures of ZnO, resulting in Ag‐NP/ZnO nanocomposites. The embedded Ag‐NPs slightly decrease the hydrophobicity of fibrous ZnO, improve its wettability, and increase the absorption of formaldehyde (H₂CO) onto the photocatalyst, all of this resulting in excellent photodegradation of formaldehyde in aqueous solution. Besides, we found that Ag‐NPs with optimal size not only accelerate the charge transfer to the surface of ZnO, but also strengthen the SPR effect in the intercolumnar channels of fibrous ZnO particles combining with high concentration of photo‐generated radical species. The micro‐to‐mesoporous ZnO is like a nanoarray packed Ag‐NPs. With Ag‐NPs of diameter 2.5 < ? < 6.5 nm, ZnO exhibits the most superior photodegradation rate constant value of 0.0239 min^?1 with total formaldehyde removal of 97%. This work presents a new feasible approach involving highly sophisticated Ag‐NP/ZnO architecture combining the SPR effect and hierarchically ordered structures, which results in high photocatalytic activity for formaldehyde photodegradation.     

Porous F-doped BiVO4: Synthesis and enhanced photocatalytic performance for the degradation of phenol under visible-light illumination

Fluoride-doped BiVO₄ with the F/Bi molar ratios of 0, 0.09, 0.13, and 0.29 (denoted as BiVO₄–F0, BiVO₄–F0.09, BiVO₄–F0.13, and BiVO₄–F0.29, respectively) were synthesized using the hydrothermal strategy with the hydrothermally derived BiVO₄ as the precursor and NH₄F as the fluoride source. Physicochemical properties of the materials were characterized by means of a number of analytical techniques. Photocatalytic activities of the fluoride-doped BiVO₄ samples were evaluated for the degradation of phenol under visible-light irradiation. It is shown that compared to the undoped BiVO₄–F0 sample, the fluoride-doped BiVO₄ samples retained the monoclinic structure, but possessed higher surface areas and oxygen adspecies concentration, better light-absorbing performance, and lower bandgap energies. Among the four samples, the porous spherical BiVO₄–F0.29 sample exhibited the best photocatalytic activity for the degradation of phenol in the presence of a small amount of H₂O₂ under visible-light illumination. It is concluded that the higher surface area and oxygen adspecies concentration, stronger optical absorbance performance, and lower bandgap energy were responsible for the excellent photocatalytic performance of BiVO₄–F0.29 for the photocatalytic degradation of phenol.     

Optical constants,dispersion energy parameters and dielectric properties of ultra-smooth nanocrystalline BiVO4 thin films prepared by rf-magnetron sputtering

BiVO₄ thin films have been prepared through radio frequency (rf) magnetron sputtering of a pre-fabricated BiVO₄ target on ITO coated glass (ITO-glass) substrate and bare glass substrates. BiVO₄ target material was prepared through solid-state reaction method by heating Bi₂O₃ and V₂O₅ mixture at 800 °C for 8 h. The films were characterized by X-ray diffraction, UV–Vis spectroscopy, LCR meter, field emission scanning electron microscopy, transmission electron microscopy and atomic force microscopy. BiVO₄ thin films deposited on the ITO-glass substrate are much smoother compared to the thin films prepared on bare glass substrate. The rms surface roughness calculated from the AFM images comes out to be 0.74 nm and 4.2 nm for the films deposited on the ITO-glass substrate and bare glass substrate for the deposition time 150 min respectively. Optical constants and energy dispersion parameters of these extra-smooth BiVO₄ thin films have been investigated in detail. Dielectric properties of the BiVO₄ thin films on ITO-glass substrate were also investigated. The frequency dependence of dielectric constant of the BiVO₄ thin films has been measured in the frequency range from 20 Hz to 2 MHz. It was found that the dielectric constant increased from 145 to 343 at 20 Hz as the film thickness increased from 90 nm to 145 nm (deposition time increased from 60 min to 150 min). It shows higher dielectric constant compared to the literature value of BiVO₄.     

基于Co3O4纳米粒子的“串联酶”活性检测葡萄糖的表面增强拉曼光谱策略

采用一种简单的湿化学法合成Co₃O₄纳米粒子(NPs),并将其作为一种"串联酶"(同时具有类过氧化物酶和类葡萄糖氧化酶活性)用于过氧化氢(H₂O₂)和葡萄糖的表面增强拉曼散射(SERS)光谱检测。作为一种灵敏的SERS底物,在pH=4.0的NaAc缓冲液条件下,Co₃O₄NPs可以催化葡萄糖和O₂生成葡萄糖酸和H₂O₂。然后H₂O₂可以氧化3,3′,5,5′-四甲基联苯胺(TMB),形成蓝色氧化产物氧化TMB(oxTMB),其在1188、1330、1610 cm^-1处表现出强烈的SERS信号。因此,我们开发了一种新的SERS策略来分析葡萄糖,检测限为1×10^-10mol·L^-1,表明Co₃O₄NPs具有生物传感器、免疫分析和医学研究的潜力。     

Photoelectrochemical Hydrogen Peroxide Production from Water on a WO3/BiVO4 Photoanode and from O2 on an Au Cathode Without External Bias

The photoelectrochemical production and degradation properties of hydrogen peroxide (H₂O₂) were investigated on a WO₃/BiVO₄ photoanode in an aqueous electrolyte of hydrogen carbonate (HCO₃⁻). High concentrations of HCO₃⁻ species rather than CO₃²⁻ species inhibited the oxidative degradation of H₂O₂ on the WO₃/BiVO₄ photoanode, resulting in effective oxidative H₂O₂ generation and accumulation from water (H₂O). Moreover, the Au cathode facilitated two‐electron reduction of oxygen (O₂), resulting in reductive H₂O₂ production with high current efficiency. Combining the WO₃/BiVO₄ photoanode with a HCO₃⁻ electrolyte and an Au cathode also produced a clean and promising design for a photoelectrode system specializing in H₂O₂ production (η _anode(H₂O₂)≈50 %, η _cathode(H₂O₂)≈90 %) even without applied voltage between the photoanode and cathode under simulated solar light through a two‐photon process; this achieved effective H₂O₂ production when using an Au‐supported porous BiVO₄ photocatalyst sheet.     

Synthesis and photocatalytic performances of BiVO4 by ammonia co-precipitation process

This paper reports the preparation and photocatalytic performance of Bismuth vanadate (BiVO₄) by a facile and inexpensive approach. An amorphous BiVO₄ was first prepared by a co-precipitation process from aqueous solutions of Bi(NO₃)₃ and NH₄VO₃ using ammonia. Followed by heating treatment at various temperatures, the amorphous phase converted to crystalline BiVO₄ with a structure between monoclinic and tetragonal scheelite. The crystallization of BiVO₄ occurred at about 523 K, while the nanocrystalline BiVO₄ were formed with a heat-treatment of lower than 673 K. However, when the heat-treatment was carried out at 773 K, the accumulation of nanocrystals to bulk particles was observed. The photocatalytic performances of the materials were investigated by O₂ evolution under visible-light, and MB decomposition under solar simulator. The results demonstrated that the crystalline structure is still the vital factor for the activities of both reactions. However, the crystallinity of BiVO₄ gives a major influence on the activity of O₂ evolution, whereas the surface area, plays an important role for photocatalytic MB decomposition.     

Unveiling the Activity and Stability Origin of BiVO4 Photoanodes with FeNi Oxyhydroxides for Oxygen Evolution

Understanding the origin of formation and active sites of oxygen evolution reaction (OER) cocatalysts is highly required for solar photoelectrochemical (PEC) devices that generate hydrogen efficiently from water. Herein, we employed a simple pH-modulated method for in situ growth of FeNi oxyhydroxide ultrathin layers on BiVO₄ photoanodes, resulting in one of the highest currently known PEC activities of 5.8 mA cm⁻² (1.23 V_RHE, AM 1.5 G) accompanied with an excellent stability. More importantly, both comparative experiments and density functional theory (DFT) studies clearly reveal that the selective formation of Bi−O−Fe interfacial bonds mainly contributes the enhanced OER activities, while the construction of V−O−Ni interfacial bonds effectively restrains the dissolution of V⁵⁺ ions and promotes the OER stability. Thereby, the synergy between iron and nickel of FeNi oxyhydroxides significantly improved the PEC water oxidation properties of BiVO₄ photoanodes.     

Boosting charge separation of BiVO4 photoanode modified with 2D metal-organic frameworks nanosheets for high-performance photoelectrochemical water splitting

Water splitting by photoelectrochemical (PEC) processes to convert solar energy into hydrogen energy using semiconductors is regarded as one of the most ideal methods to solve the current energy crisis and has attracted widespread attention. Herein, Co-based metal-organic framework (Co(bpdc)(H₂O)₄ (Co-MOF) nanosheets as passivation layers were in-situ constructed on the surface of BiVO₄ films through an uncomplicated hydrothermal method (Co-MOF/BiVO₄). Under AM 1.5G illumination, synthesized Co-MOF/BiVO₄ electrode exhibited a 4-fold higher photocurrent than bare BiVO₄, measuring 6.0 mA/cm² at 1.23 V vs. RHE in 1 mol/L potassium borate electrolyte (pH 9.5) solution. Moreover, the Co-MOF/BiVO₄ film demonstrated a 96% charge separation efficiency, a result caused by an inhibited recombination rate of photogenerated electrons and holes by the addition of Co-MOF nanosheets. This work provides an idea for depositing inexpensive 2D Co-MOF nanosheets on the photoanode as an excellent passivation layer for solar fuel production.     

Morphology Engineering of BiVO4 with CoOx Derived from Cobalt-containing Polyoxometalate as Co-catalyst for Oxygen Evolution

Bismuth vanadate (BiVO₄) as a metal oxidation semiconductor has stimulated extensive attention in the photocatalytic water splitting field. However, the poor transport ability and easy recombination of charge carriers limit photocatalytic water oxidation activity of pure BiVO₄. Herein, the photocatalytic activity of BiVO₄ is enhanced via adjusting its morphology and combination co-catalyst. First, the Cu-BiVO₄ was synthesized by copper doping to control the growth of {110} facet of BiVO₄, which is regarded for the separation of photo-generated charge carriers. Then the CoO_x in-situ generated from K₆[SiCo^II(H₂O)W₁₁O₃₉] ⋅ 16H₂O was photo-deposited on Cu-BiVO₄ surface as co-catalyst to speed up reaction kinetics. Cu-BiVO₄@CoO_x hybrid catalyst shows highest photocatalytic activity and best stability among all the prepared catalysts. Oxygen evolution is about 34.6 μmol in pH 4 acetic acid buffer under 420 nm LED irradiation, which is nearly 20 times higher than that of pure BiVO₄. Apparent quantum efficiency (AQE) in 1 h and O₂ yield are 1.83% and 23.1%, respectively. O₂ evolution amount nearly maintains the original value even after 5 cycles.     

Near infrared-driven photoelectrochemical water splitting: Review and future prospects

Photoelectrochemical (PEC) water splitting supplies an environmentally friendly, sustainable approach to generating renewable hydrogen fuels. Oxides semiconductors, e.g. TiO₂, BiVO₄, and Fe₂O₃, have been widely developed as photoelectrodes to demonstrate the utility in PEC systems. Even though significant effort has been made to increase the PEC efficiency, these materials are still far from practical applications. The main issue of metal oxides is the wide bandgap energy that hinders effective photons harvesting from sunlight. In solar spectrum, over 40% of the energy is located in the near-infrared (NIR) region. Developing sophisticated PEC systems that can be driven by NIR illumination is therefore essential. This review gives a concise overview on PEC systems based on the use of NIR-driven photoelectrodes. Promising candidates as efficient yet practical NIR-responsive photoelectrodes are suggested and discussed. Future outlooks on the advancement of PEC water splitting are also proposed.     

Catalytic reduction of hazardous acid orange 10 dye by BiVO4/TiO2 nanocrystalline heterojunction and influence of aeration,FeSO4, H2O2 and FeCl3 on removal efficiency: A novel and environmentally friendly process

Bismuth vanadate in combination with titanium dioxide were synthesized by hydrothermal method and its photocatalytic activity was investigated under visible light irradiation for acid orange 10 (AO10) dye removal. The 10% BiVO₄/TiO₂ showed the highest catalytic activity in comparison with 20, 30, 40 and 50% BiVO₄/TiO₂ ratios. The removal of AO10 azo dye in aqueous solutions was studied in laboratory-scale experiments using 25 removal processes and their removal efficiencieswere evaluated, separately. The results showed that the amount of de-colorization for each oxidation process is completely different. The order of the investigated processes in removing the dye after 90 min is as follows: LED < TiO₂ < BiVO₄ < 10% BT/without LED < BiVO₄/ LED < 50% BT < 40% BT < 30% BT < 20% BT < UV/H₂O₂ < 10% BT < 5a-10 %BT < 5F-10 %BT < 10a-10 %BT < 50F-10 %BT < 20a-10 %BT < 10F-10 %BT < 20F-10 %BT < 20H_-10 %BT < 40H-10 %BT < 50H_-10 %BT < 20a-20F-10 %BT < 20a-20F-50H_-10 %BT. Among the above processes, 20a-20F-50H-10 %BT had the best removal performance and can be suggested for using in real conditions. Coagulation/precipitation process was done using 5 mg/L of FeCl₃ as post-treatment reaching efficiency of 100% in the studied system.     

Metal-Organic Framework Glass Catalysts from Melting Glass-Forming Cobalt-Based Zeolitic Imidazolate Framework for Boosting Photoelectrochemical Water Oxidation

Sluggish oxygen evolution kinetics and serious charge recombination restrict the development of photoelectrochemical (PEC) water splitting. The advancement of novel metal–organic frameworks (MOFs) catalysts bears practical significance for improving PEC water splitting performance. Herein, a MOF glass catalyst through melting glass-forming cobalt-based zeolitic imidazolate framework (Co-a_gZIF-62) was introduced on various metal oxide (MO: Fe₂O₃, WO₃ and BiVO₄) semiconductor substrates coupled with NiO hole transport layer, constructing the integrated Co-a_gZIF-62/NiO/MO photoanodes. Owing to the excellent conductivity, stability and open active sites of MOF glass, Co-a_gZIF-62/NiO/MO photoanodes exhibit a significantly enhanced photoelectrochemical water oxidation activity and stability in comparison to pristine MO photoanodes. From experimental analyses and density functional theory calculations, Co-a_gZIF-62 can effectively promote charge transfer and separation, improve carrier mobility, accelerate the kinetics of oxygen evolution reaction (OER), and thus improve PEC performance. This MOF glass not only serves as an excellent OER cocatalyst on tunable photoelectrodes, but also enables promising opportunities for PEC devices for solar energy conversion.     

Nano Au enhanced upconversion in dichroic Nd3+:Au–antimony glass nanocomposites

Dichroic Nd³⁺:Au–antimony glass (K₂O–B₂O₃–Sb₂O₃) nanocomposites (NCs) have been synthesized by single-step melt-quench thermochemical reduction process. The UV–Vis–NIR spectra show surface plasmon resonance (SPR) band of Au⁰ nanoparticles (NPs) and absorption peaks of Nd³⁺ ions. XRD and SAED results indicate growth of Au⁰ NPs along (200) plane. TEM image reveals elliptical Au⁰ NPs having sizes 12–21 nm (aspect ratio ～1.2) responsible for the dichroic behavior. Photoluminescent upconversion under excitation at 805 nm exhibit two emission bands of Nd³⁺ ions at 540 (green) and 650 (red) nm due to ⁴G_7/2 → ⁴I_9/2 and ⁴G_7/2 → ⁴I_13/2 transitions respectively. Both bands undergo maximum 8 and 11 fold intensity enhancements respectively at 0.03 wt% Au⁰ (4.1 × 10¹⁸ atoms/cm³). Local field enhancement (LFE) induced by Au⁰ SPR and energy transfer (ET) from Au⁰ → Nd³⁺ is found to be responsible for enhancement while ET from Nd³⁺ → Au⁰ and optical re-absorption due to Au⁰ SPR for quenching.