超声喷雾热分解WO_3薄膜的光电化学制氢研究

Characterization of Ultrasonic Spray Pyrolysis Deposited WO_3 Thin Film for Photoelectrochemical Splitting of Water

以H2O2在93℃水浴中溶解H2WO4得到的溶液作为超声喷雾热分解反应的前驱液制备WO3薄膜,考查了H2O2添加量及前驱液浓度对薄膜结构和光电化学制氢性能的影响.结果表明,增加前驱液中H2O2的添加量和降低前驱液浓度都能使薄膜表面由网状结构分裂成颗粒堆积结构,低浓度前驱液制备的薄膜表面经热处理后会结晶出尺寸较大的颗粒.前驱液浓度越高或H2O2添加量越多,则平带电位变得越负.光电转换效率(IPCE)测量结果表明,对于所有样品,在电极电位(饱和甘汞电极)为0.5 V时,光照产生光电流的起始波长都为450 nm.在强度较弱的单色光照射下,光电效率随H2O2添加量的增加和前驱液浓度的降低都先增大后减小.氙灯直接照射下的光电流测试结果表明,H2O2添加量对光电流的影响不大,而前驱液浓度的降低增大了光电流.

WO3 films were deposited by ultrasonic spray pyrolysis using the precursor obtained by dissolving tungsten acid in hydrogen peroxide aqueous solution in 366 K water bath. The effect on the structure and photoelectrochemical properties of WO3 films by varying amount of hydrogen peroxide and concentration of precursor was investigated. It is found that increase in amount of hydrogen peroxide and decrease in concentration of precursor lead to more cracks on the networklike film surface to transform it into a particle-assembled structure, while the particles in the films deposited with low concentration precursor crystallize to large grains after annealing process. The flat-band potential shifts negatively with both increasing hydrogen peroxide and precursor concentration. The incident photon to current efficiency （IPCE） first increases and then decreases with the increasing hydrogen peroxide and decreasing precursor concentration. The same photocurrent onset wavelength for all the films is observed as 450 nm with the illumination light wavelength scan from long length to short. The photocurrent-voltage feature under high intensity illumination from Xe lamp reveals that photocurrent increases with lower concentration of precursor, while the photocurrent changes little with different amount of hydrogen peroxide.