四角星形BiVO4/Bi2O3催化剂的制备及性能

采用水热法合成具有四角星形貌的钒酸铋,再将钒酸铋浸渍在碱溶液里二次水热,制备出BiVO_4/Bi_2O_3催化剂。采用X射线粉末衍射(XRD)、扫描电子显微镜(SEM),紫外-可见漫反射(UV-Vis DRS)等方法对样品进行表征。可见光下,BiVO_4/Bi_2O_3复合物的光催化降解罗丹明B性能及光电流响应均优于纯BiVO_4。这是由于BiVO_4/Bi_2O_3复合材料形成了异质结构,有效抑制了光生电子与空穴的复合效率。     

四角星形BiVO4/Bi2O3催化剂的制备及性能研究

采用水热法合成具有四角星形貌的钒酸铋,再将钒酸铋浸渍在碱溶液里二次水热,制备出BiVO₄/Bi₂O₃催化剂。采用X射线粉末衍射(XRD)、扫描电子显微镜(SEM),紫外-射(UV-Vis DRS)等方法征。可见光下,BiVO₄/Bi₂O₃复合物的光催化降解丹明B性能及光电优于纯BiVO₄。BiVO₄/Bi₂O₃复合材料形成了异质结构,有效抑制了光电子与空穴的复合效率。     

Prussian Blue Type Cocatalysts for Enhancing the Photocatalytic Water Oxidation Performance of BiVO4

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 M^II-Co^III 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 M^II-Co^III 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.     

Synthesis, characterization and photocatalytic application of H3PW12O40/BiVO4 composite photocatalyst

A series of H3PW12O40/BiVO4 composite with different H3PW12O40 loadings were prepared using a hydrothermal and impregnation method. The prepared composites were characterized by XRD, Raman, SEM, XPS, and DRS techniques. The bandgap of the composite was narrower compared with the as-prepared pure BiVO4 . As a novel photocatalytic material, the photocatalytic performance of the H3PW12O40/BiVO4 composite was investigated by the degradation of methylene blue (MB) dye solution under visible light irradiation and compared with that of pure BiVO4 . The results revealed that the introduction of H3PW12O40 could improve the photocatalytic performance and different concentrations of H3PW12O40 resulted in different photocatalytic activities. The highest activity was obtained by the sample with a loading HPW concentration of 10 wt%. The reason for the enhanced photocatalytic activities of H3PW12O40/BiVO4 samples was also discussed in this paper. Moreover, the H3PW12O40/BiVO4 composites retained the catalytic activity after four repeated experiments.     

Simulated Sunlight-Driven Degradation of Rhodamine B by Porous Peanut-Like TiO2/BiVO4 Composite

Porous peanut-like TiO₂/BiVO₄ composite nanostructures were synthesized via a template-free hydrothermal process with bismuth nitrate, ammonium metavanadate and anatase TiO₂ as raw materials. The crystal structures, morphologies, and optical properties of the as-prepared samples were characterized by X-ray powder diffraction, transmission electron microscope, scanning electron microscopy, X-ray photoelectron spectroscopy and UV–visible absorption spectra. Simulated sun-light induced photocatalytic degradation of Rhodamine B by porous peanut-like TiO₂/BiVO₄ nanostructures in the absence and presence of H₂O₂ has been investigated, and the results show these porous composite nanostructures with higher photocatalytic activity than pure BiVO₄ and anatase TiO₂. When TiO₂/BiVO₄ heterostructures were used as the photocatalysts under simulated sun-light irradiation, BiVO₄ could act as a sensitizer to absorb the visible light. Meanwhile, coupling different band-gap semiconductors of TiO₂ and BiVO₄, the compound facilitate separation of the photogenerated carriers under the internal field induced by the different electronic band structures of semiconductors.     

一步醇-水热法合成高效的F掺杂BiVO4光催化剂

以NH₄F为掺杂前体,采用简单的一步醇-水热法制备了F掺杂BiVO₄光催化剂。利用X射线衍射（XRD）、扫描电子显微镜（SEM）、X射线光电子能谱（XPS）、紫外-可见漫反射光谱（UV-Vis）和光致发光光谱（PL）表征了这些光催化剂的物理化学性质。在少量H₂O₂存在条件下,以可见光照射下光催化降解苯酚的反应测定了这些光催化剂的催化活性。研究表明,相较于未掺杂的BiVO₄样品而言,F掺杂BiVO₄样品不仅仍保留了单斜结构,而且有更高的结晶度、表面氧空位密度和光生电荷载流子分离效率,更强的光吸收和更低的带隙能。在这些F掺杂BiVO₄样品中,以n_F/n_Bi的理论值为1.0且带隙能为2.43 eV的F掺杂BiVO₄样品的光催化活性最好（90 min内苯酚的降解率可达95%）。这一优良的光催化性能与其具有最高的结晶度、表面氧空位密度和光生电荷载流子分离效率,最强的光吸收和最低的带隙能有关。     

Nanoplasmonic zirconium nitride photocatalyst for direct overall water splitting

The ability of plasmonic nanostructures to efficiently harvest light energy and generate energetic hot carriers makes them promising materials for utilization in photocatalytic water spitting.Apart from the traditional Au and Ag based plasmonic photocatalysts,more recently the noble-metal-free alternative plasmonic materials have attracted ever-increasing interest.Here we report the first use of plasmonic zirconium nitride（ZrN） nanoparticles as a promising photocatalyst for water splitting.Highl...     

2D/2D atomic double-layer WS2/Nb2O5 shell/core nanosheets with ultrafast interfacial charge transfer for boosting photocatalytic H2 evolution

Low-efficiency charge transfer is a critical factor to limit the photocatalytic H₂ evolution activity of semiconductor photocatalysts. The interface design is a promising approach to achieve high charge-transfer efficiency for photocatalysts. Herein, a new 2D/2D atomic double-layer WS₂/Nb₂O₅ shell/core photocatalyst (DLWS/Nb₂O₅) is designed. The atom-resolved HAADF-STEM results unravel the presence of an unusual 2D/2D shell/core interface in DLWS/Nb₂O₅. Taking advantage of the advanced femtosecond-resolved ultrafast TAS spectra, the average lifetime of charge carriers for DLWS/Nb₂O₅ (180.97 ps) is considerably shortened as compared to that of Nb₂O₅ (230.50 ps), strongly indicating that the 2D/2D shell/core interface enables DLWS/Nb₂O₅ to achieve ultrafast charge transfer from Nb₂O₅ to atomic double-layer WS₂, thus yielding a high photocatalytic H₂ evolution rate of 237.6 μmol/h, up to 10.8 times higher than that of pure Nb₂O₅ nanosheet. This study will open a new window for the development of high-efficient photocatalytic systems through the interface design.     

Z‐Scheme Photocatalytic Water Splitting on a 2D Heterostructure of Black Phosphorus/Bismuth Vanadate Using Visible Light

Spontaneously solar‐driven water splitting to produce H₂ and O₂, that is, the conversion of solar energy to chemical energy is a dream of mankind. However, it is difficult to make overall water splitting feasible without using any sacrificial agents and external bias. Drawing inspiration from nature, a new artificial Z‐scheme photocatalytic system has been designed herein based on the two‐dimensional (2D) heterostructure of black phosphorus (BP)/bismuth vanadate (BiVO₄). An effective charge separation makes possible the reduction and oxidation of water on BP and BiVO₄, respectively. The optimum H₂ and O₂ production rates on BP/BiVO₄ were approximately 160 and 102 μmol g^?1 h^?1 under irradiation of light with a wavelength longer than 420 nm, without using any sacrificial agents or external bias.     

Semi-chemical interaction between graphitic carbon nitride and Pt for boosting photocatalytic hydrogen evolution

Owing to the exorbitant overpotential and serious carrier recombination of graphitic carbon nitride （gC₃N₄）,noble metal （NM） is usually served as the H₂evolution co-catalyst.Although the NM （such as Pt）nanoparticles can reduce the H₂evolution overpotential,the weak van der Waals interaction between Pt and g-C₃N₄makes against the charge transfer.Herein,the solvothermal method is developed to achieve semi-chemical interaction betwee...     

BiVO4/ZnFe2O4同型异质结光阳极的构筑及其光电催化分解水性能

光生电子-空穴对的复合被认为是限制BiVO₄材料光电催化转换效率的重要原因之一。基于此,通过简单的水热-煅烧方法构筑了 BiVO₄/ZnFe₂O₄同型异质结光阳极,BiVO₄/ZnFe₂O₄复合光阳极在 1.23 V(vs RHE)下的光电流密度为 3.33 mA·cm^-2,较纯BiVO₄提升了2倍 (1.20 mA·cm^-2)。相关的结构及性能测试表明,BiVO₄和ZnFe₂O₄形成了带隙错开的n-n异质结,使得光生载流子得到有效分离,更有效地参与水氧化过程,进而提高了BiVO₄的光电催化水分解性能。     

B离子掺杂TiO2催化剂(TiO2－xBx)光催化活性的研究

采用溶胶-凝胶法制备出纳米TiO₂和TiO_2－xB_x催化剂. 光催化实验证明, TiO_2－xB_x催化剂的紫外、可见光催化活性均高于TiO₂. XRD, XPS和Raman结果表明, B离子是以取代式掺杂占据了TiO₂的O^2－的晶格位置. UV-Vis和PL谱的结果表明, B离子的2p轨道与O的2p轨道形成混合价带, 产生可见光响应, B离子的掺入有效地阻止了光生载流子的复合, 促进了其分离, 是TiO_2－xB_x催化剂紫外、可见光催化活性提高的主要原因.     

Molten-Salt-Mediated Synthesis of an Atomic Nickel Co-catalyst on TiO2 for Improved Photocatalytic H2 Evolution

Atomic co-catalysts offer high potential to improve the photocatalytic performance, of which the preparation with earth-abundant elements is challenging. Here, a new molten salt method (MSM) is designed to prepare atomic Ni co-catalyst on widely studied TiO₂ nanoparticles. The liquid environment and space confinement effect of the molten salt leads to atomic dispersion of Ni ions on TiO₂, while the strong polarizing force provided by the molten salt promotes formation of strong Ni−O bonds. Interestingly, Ni atoms are found to facilitate the formation of oxygen vacancies (OV) on TiO₂ during the MSM process, which benefits the charge transfer and hydrogen evolution reaction. The synergy of atomic Ni co-catalyst and OV results in 4-time increase in H₂ evolution rate compared to that of the Ni co-catalyst on TiO₂ prepared by an impregnation method. This work provides a new strategy of controlling atomic co-catalyst together with defects for efficient photocatalytic water splitting.     

TiO2/BiVO4, a Heterojuncted Microfiber with Enhanced Photocatalytic Performance for Methylene Blue under Visible Light Irradiation

Novel TiO₂/BiVO₄ microfiber heterojunctions were constructed using cotton as biomorphic templates. The as-synthesized samples were characterized by scanning electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy, UV-Vis diffuse reflectance spectra and photocatalytic experiment. The morphology of the as-synthesized TiO₂/BiVO₄ composites was consisted of a large quantity of microfiber structures with diameter from 2.5 μm to 5 μm, and the surface of samples became more coarse and compact with the increase of weight ratio of TiO₂. The TiO₂/BiVO₄ samples with proper content (10.00wt%) showed the highest pho-tocatalytic degradation activity for methylene blue (MB) degradation among all the samples under visible light, and 88.58%MB could be degraded within 150 min. The enhancement of photocatalytic activity was mainly attributed to the formation of n-n heterojunction at the contact interface of TiO₂ and BiVO₄, which not only narrowed the band gap of BiVO₄ for extending the absorption range of visible light, but also promoted the transfer of charge carriers across interface. A possible photodegradation mechanism of MB in the presence of TiO₂/BiVO₄ microfibrous photocatalyst was proposed.     

Importance of catalyst–photoabsorber interface design configuration on the performance of Mo-doped BiVO4 water splitting photoanodes

Photoelectrochemical water splitting is mostly impeded by the slow kinetics of the oxygen evolution reaction. The construction of photoanodes that appreciably enhance the efficiency of this process is of vital technological importance towards solar fuel synthesis. In this work, Mo-modified BiVO₄ (Mo:BiVO₄), a promising water splitting photoanode, was modified with various oxygen evolution catalysts in two distinct configurations, with the catalysts either deposited on the surface of Mo:BiVO₄ or embedded inside a Mo:BiVO₄ film. The investigated catalysts included monometallic, bimetallic, and trimetallic oxides with spinel and layered structures, and nickel boride (Ni_xB). In order to follow the influence of the incorporated catalysts and their respective properties, as well as the photoanode architecture on photoelectrochemical water oxidation, the fabricated photoanodes were characterised for their optical, morphological, and structural properties, photoelectrocatalytic activity with respect to evolved oxygen, and recombination rates of the photogenerated charge carriers. The architecture of the catalyst-modified Mo:BiVO₄ photoanode was found to play a more decisive role than the nature of the catalyst on the performance of the photoanode in photoelectrocatalytic water oxidation. Differences in the photoelectrocatalytic activity of the various catalyst-modified Mo:BiVO₄ photoanodes are attributed to the electronic structure of the materials revealed through differences in the Fermi energy levels. This work thus expands on the current knowledge towards the design of future practical photoanodes for photoelectrocatalytic water oxidation.

     

A Theoretical Study on the Mechanism of Photocatalytic Oxygen Evolution on BiVO4 in Aqueous Solution

The oxygen evolution reaction (OER) is regarded as one of the key issues in achieving efficient photocatalytic water splitting. Monoclinic scheelite BiVO₄ is a visible‐light‐responsive semiconductor which has proved to be effective for oxygen evolution. Recently, the synthesis of a series of monoclinic BiVO₄ single crystals was reported, and it was found that the (010), (110), and (011) facets are highly exposed and that the photocatalytic O₂ evolution activity depends on the degree of exposure of the (010) facets. To explore the properties of and photocatalytic water oxidation reaction on different facets, DFT calculations were performed to investigate the geometric structure, optical properties, electronic structure, water adsorption, and the whole OER free‐energy profiles on BiVO₄ (010) and (011) facets. The calculated results suggest both favorable and unfavorable factors for OER on the (010) and the (011) facets. Due to the combined effects of the above‐mentioned factors, different facets exhibit quite different photocatalytic activities.     

BiVO4/ZnFe2O4同型异质结光阳极的构筑及其光电催化分解水性能

光生电子-空穴对的复合被认为是限制BiVO₄材料光电催化转换效率的重要原因之一。基于此,通过简单的水热-煅烧方法构筑了BiVO₄/ZnFe₂O₄同型异质结光阳极,BiVO₄/ZnFe₂O₄复合光阳极在1.23 V(vs RHE)下的光电流密度为3.33 mA·cm^-2,较纯BiVO₄提升了2倍(1.20 mA·cm^-2)。相关的结构及性能测试表明,BiVO₄和ZnFe₂O₄形成了带隙错开的n-n异质结,使得光生载流子得到有效分离,更有效地参与水氧化过程,进而提高了BiVO₄的光电催化水分解性能。     

ZnIn2S4 flowerlike microspheres embedded with carbon quantum dots for efficient photocatalytic reduction of Cr(VI)

Development of efficient heterostructured photocatalysts that respond to visible light remains a considerable challenge. We herein show the synthesis of ZnIn₂S₄/carbon quantum dot hybrid photocatalysts with flowerlike microspheres via a facile solvothermal method. The ZnIn₂S₄/carbon quantum dot flowerlike microspheres display enhanced photocatalytic and photoelectrochemical activity compared with that of pure ZnIn₂S₄. With a content of only 0.5 wt % carbon quantum dots, 93% of Cr(VI) is reduced under visible-light irradiation at 40 min. As a co-catalyst, the carbon quantum dots improve the light absorption and lengthen the lifetime of charge carriers, consequently enhancing the photocatalytic and photoelectrochemical activity.     

A Hydrogen Farm Strategy for Scalable Solar Hydrogen Production with Particulate Photocatalysts

Scalable solar hydrogen production by water splitting using particulate photocatalysts is promising for renewable energy utilization. However, photocatalytic overall water splitting is challenging owing to slow water oxidation kinetics, severe reverse reaction, and H₂/O₂ gas separation. Herein, mimicking nature photosynthesis, a practically feasible approach named Hydrogen Farm Project (HFP) is presented, which is composed of solar energy capturing and hydrogen production subsystems integrated by a shuttle ion loop, Fe³⁺/Fe²⁺. Well‐defined BiVO₄ crystals with precisely tuned {110}/{010} facets are ideal photocatalysts to realize the HFP, giving up to 71 % quantum efficiency for photocatalytic water oxidation and full forward reaction with nearly no reverse reaction. An overall solar‐to‐chemical efficiency over 1.9 % and a solar‐to‐hydrogen efficiency exceeding 1.8 % could be achieved. Furthermore, a scalable HFP panel for solar energy storage was demonstrated under sunlight outdoors.     

磁性BiVO4可见光催化材料的制备及光催化性能

采用水相沉淀法,以Fe3O4粒子为核心,令BiVO4沉淀附着于其上,制备了一种更易于从溶液中分离的磁性BiVO4可见光催化材料,以XRD、SEM、UV-Vis DRS、低温氮吸附-脱附等对其进行了表征。结果表明制备的磁性BiVO4为单斜白钨矿型,颗粒呈片状,粒径比普通BiVO4有所增大,在可见光区的吸收更强,吸收边红移程度随Fe3O4含量增加而增大,但比表面积并没有明显改变。并以可见光(λ≥400 nm)为光源,以亚甲基蓝溶液模拟染料废水,考察了其可见光催化活性,发现与纯BiVO4相比,磁性BiVO4具有更为良好的催化性能。通过考察各催化剂的DRS图谱以及暗反应后亚甲基蓝的浓度,发现这种降解效率上的提高是禁带宽度(Eg)降低、可见光吸收增加和对亚甲基蓝吸附量增大综合作用所导致的。这种吸附量的提升与比表面积无关,本工作以等电点的影响来解释此原因。