电解液成分、厚度及表面改性对旋涂法制备的BiVO4膜层光电化学性能的影响

摘要

采用旋涂法在FTO(SnO2∶F)导电玻璃衬底上沉积得到BiVO4多孔薄膜用以光解水,改变前驱体的浓度和旋涂次数以调控薄膜的厚度.研究了电解液成分、膜层厚度及表面改性等因素对刚经历过退火处理的BiVO4薄膜光电化学(PEC)性能的影响.结果表明:通过在电解液中添加适量的空穴吞噬剂Na2SO3,或对表面进行Co-Pi改性均能有效改善BiVO4薄膜的PEC活性.这些措施均能有效抑制同液界面处的载流子复合反应.经Co-Pi改性的BiVO4薄膜在0.6 V(vs SCE)偏压下,0.1 mol· L-1 Na2SO4+0.1mol·L-1Na2SO3的电解液中展现出最高的光电流密度(4.3 mA ·cm-2).此外,选用一个代表性BiVO4薄膜作为光阳极制备了一个PEC生物传感器,在检测谷胱甘肽(GSH)上表现出比较高的灵敏度.本研究证实了BiVO4薄膜的PEC性能严重依赖着光俘获效率和载流子输运过程.%Porous BiVO4 thin films have been prepared on the fluorine doped tin oxide (SnO2∶F) coated glass substrates through a facile spin-coating strategy for water splitting application.The film thickness was tuned by varying the deposition cycles and the precursor concentration,respectively.The influences of electrolyte composition,film thickness and surface modification were investigated on the actual photoelectrochemical (PEC) performance of the as-annealed BiVO4 porous films.The results show that the PEC activity of BiVO4 can be enhanced effectively by adding a hole scavenger Na2SO3 with suitable amount into the electrolyte,or modified the surface with a co-catalyst Co-Pi.These methods can suppress the carrier recombination that occurs at the solid/ liquid interface.The highest photocurrent density (4.3 mA·cm-2 at a bias of 0.6 V (vs SCE)) was achieved in the BiVO4 samples which were synthesized at the optimal condition and characterized under a visible-light irradiation intensity of 100 mW·cm-2,using a 0.1 mol·L-1 Na2SO4+0.1 mol· L-1 Na2SO3 electrolyte.Additionally,a facile PEC bio-sensor is constructed by using a BiVO4 film anode,leading to an acceptable sensitivity for detecting the glutathione (GSH).In a word,it is demonstrated that the PEC performance of BiVO4 is dependent on both the light harvesting and carrier diffusion process.