Electrical transport properties of bismuth vanadate(BiVO4) are studied under high pressures with electrochemical impedance spectroscopy. A pressure-induced ionic-electronic transition is found in BiVO4. Below 3.0 GPa,...Electrical transport properties of bismuth vanadate(BiVO4) are studied under high pressures with electrochemical impedance spectroscopy. A pressure-induced ionic-electronic transition is found in BiVO4. Below 3.0 GPa, BiVO4 has ionic conduction behavior. The ionic resistance decreases under high pressures due to the increasing migration rate of O2-ions. Above 3.0 GPa the channels for ion migration are closed. Transport mechanism changes from the ionic to the electronic behavior. First-principles calculations show that bandgap width narrows under high pressures, causing the continuous decrease of electrical resistance of BiVO4.展开更多
Bismuth vanadate is a promising photoanode material for photoelectrochemical (PEC) water splitting, but its activity and stability need to be further improved. In this work, we synthesized Ni-doped BiVO 4 abundant wit...Bismuth vanadate is a promising photoanode material for photoelectrochemical (PEC) water splitting, but its activity and stability need to be further improved. In this work, we synthesized Ni-doped BiVO 4 abundant with V 4+ species and oxygen defects through an in situ electrodeposition method. The eff ective doping can decrease the particle size of BiVO 4 and lead to the formation of V 4+ species/oxygen defects. Accordingly, the doped and defective BiVO 4 showed high optical absorption and rapid charge transfer, and further showed much higher PEC activity than pure BiVO 4 . Specifi cally, 5-Ni-BiVO 4 exhibits the highest activity in PEC water splitting, with a photocurrent of 2.39 mA/cm 2 at 1.23 V versus RHE (the reversible hydrogen electrode), which is 2.5 times higher than pure BiVO 4 (0.94 mA/cm 2 ), and much higher incident photon-to-current effi ciency (IPCE) value of 45%(while only 25% for BiVO 4 at ca. 400 nm). This work provides an in situ method for the development of a high-performance photoanode.展开更多
以Bi(NO3)3.5H2O、NaVO3和Cu(NO3)2.3H2O为原料并以十六烷基三甲基溴化铵(CTAB)为结构导向剂通过水热法制备了Cu/BiVO4微米片晶体。采用XRD、XPS、SEM、HRTEM、UV-Vis、比表面积测试等对产品进行了表征。结果表明,2.0 g CTAB辅助水热法...以Bi(NO3)3.5H2O、NaVO3和Cu(NO3)2.3H2O为原料并以十六烷基三甲基溴化铵(CTAB)为结构导向剂通过水热法制备了Cu/BiVO4微米片晶体。采用XRD、XPS、SEM、HRTEM、UV-Vis、比表面积测试等对产品进行了表征。结果表明,2.0 g CTAB辅助水热法能够合成结晶度高且形貌规整的单斜白钨矿Cu/BiVO4微米片晶体,其长度为1.0～2.0μm,宽度为0.5～2.0μm,厚度在200～300 nm内。相比BiVO4颗粒,片状Cu/BiVO4样品的紫外–可见光吸收边发生了稍许红移,具有较小的能带隙。光催化结果说明,5.0wt%Cu/BiVO4微米片表现出最好的光催化活性,其速度常数k为5.89×10–2/min,可见光照射10 mg/L亚甲基蓝溶液60 min的光解率达100%。展开更多
BiVO4, BiVO4@C3N4 and BiVO4@C3N4@GO composite photo-catalysts were synthesized, and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), transmission elec...BiVO4, BiVO4@C3N4 and BiVO4@C3N4@GO composite photo-catalysts were synthesized, and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), transmission electron microscopy (TEM), ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS), Fourier transform infrared spectroscopy (FT-IR), and Brunauer-Emmett-Teller (BET) surface area techniques. The photocatalytic activity was evaluated on the degradation of methylene blue (MB) under visible light irradiation, which denoted that the BiVO4@C3N4@GO ternary composite outperformed the binary composite BiVO4@C3N4 and BiVO4. Then the effects of catalyst dosage, initial pH value, and initial methylene blue concentration on the degradation process were investigated systematically. The improvement of visible-light photocatalytic degradation performance was attributed to the enhanced visible light absorption, larger surface area, higher adsorption ability, and prolonged lifetime of photo-generated electron-hole pairs. The recycle experiments results showed that the BiVO4@C3N4@GO composite had excellent photo-stability for MB photocatalytic degradation.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 11774126,11774174 and 11404133
文摘Electrical transport properties of bismuth vanadate(BiVO4) are studied under high pressures with electrochemical impedance spectroscopy. A pressure-induced ionic-electronic transition is found in BiVO4. Below 3.0 GPa, BiVO4 has ionic conduction behavior. The ionic resistance decreases under high pressures due to the increasing migration rate of O2-ions. Above 3.0 GPa the channels for ion migration are closed. Transport mechanism changes from the ionic to the electronic behavior. First-principles calculations show that bandgap width narrows under high pressures, causing the continuous decrease of electrical resistance of BiVO4.
基金support from the National Natural Science Foundation of China (Nos. 51661145026,21506156, 21676193)the Tianjin Municipal Natural Science Foundation (No. 16JCQNJC05200)
文摘Bismuth vanadate is a promising photoanode material for photoelectrochemical (PEC) water splitting, but its activity and stability need to be further improved. In this work, we synthesized Ni-doped BiVO 4 abundant with V 4+ species and oxygen defects through an in situ electrodeposition method. The eff ective doping can decrease the particle size of BiVO 4 and lead to the formation of V 4+ species/oxygen defects. Accordingly, the doped and defective BiVO 4 showed high optical absorption and rapid charge transfer, and further showed much higher PEC activity than pure BiVO 4 . Specifi cally, 5-Ni-BiVO 4 exhibits the highest activity in PEC water splitting, with a photocurrent of 2.39 mA/cm 2 at 1.23 V versus RHE (the reversible hydrogen electrode), which is 2.5 times higher than pure BiVO 4 (0.94 mA/cm 2 ), and much higher incident photon-to-current effi ciency (IPCE) value of 45%(while only 25% for BiVO 4 at ca. 400 nm). This work provides an in situ method for the development of a high-performance photoanode.
基金the Natural Science Foundation of Heilongjiang Province of China [QC2017005]the Province Postdoctoral Fund [LBH-Z15032]
文摘BiVO4, BiVO4@C3N4 and BiVO4@C3N4@GO composite photo-catalysts were synthesized, and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), transmission electron microscopy (TEM), ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS), Fourier transform infrared spectroscopy (FT-IR), and Brunauer-Emmett-Teller (BET) surface area techniques. The photocatalytic activity was evaluated on the degradation of methylene blue (MB) under visible light irradiation, which denoted that the BiVO4@C3N4@GO ternary composite outperformed the binary composite BiVO4@C3N4 and BiVO4. Then the effects of catalyst dosage, initial pH value, and initial methylene blue concentration on the degradation process were investigated systematically. The improvement of visible-light photocatalytic degradation performance was attributed to the enhanced visible light absorption, larger surface area, higher adsorption ability, and prolonged lifetime of photo-generated electron-hole pairs. The recycle experiments results showed that the BiVO4@C3N4@GO composite had excellent photo-stability for MB photocatalytic degradation.
