WO3 photoanodes for photoelectrochemical applications

WO3 layers were prepared by spray pyrolysis of a peroxotungstic acid solution on FTO/glass substrates. Investigated parameters were layer thickness and influence of post-annealing in air. Films deposited at 250 °C were amorphous. Post-annealing at 550 °C for 2 h resulted in the formation of monoclinic crystalline structure. A comprehensive account of electrochemical efficiency in terms of IPCE for WO3 films as a function of the three parameters (wavelength, thickness and direction of light incidence) fully characterizing the photoelectrodes is presented here for the first time. The highest improvement in crystallinity and also the highest photocurrent response was found for WO3 layers deposited at 250 °C and post-annealed at 550 °C, namely 1.9 mA/cm2 (in 0.1 M HClO4 at 1.6 V vs. Ag/AgCl) under irradiation with a solar simulator (AM 1.5, 100 mW/cm2) and IPCE = 0.5 at 369 nm (front side irradiation), which is comparable with values obtained by other deposition techniques (e.g., hydrothermal or sol gel). Spray pyrolysis as a method of fabricating WO3 electrodes has the advantage of being able to produce large electrodes for use in practical applications.三氧化钨（WO3）薄膜通过在FTO/玻璃衬底上对过氧钨酸溶液进行喷雾热解制备。本研究考察的参数包括薄膜厚度以及空气中后退火工艺的影响。250℃下沉积的薄膜呈非晶态；经550℃退火2小时后，薄膜形成单斜晶结构。本研究首次全面报道了三氧化钨薄膜基于入射光子-电子转换效率（IPCE, Incident Photon-to-Current Efficiency）的电化学性能，该性能随三个完整表征光电极的关键参数变化：波长、薄膜厚度以及光入射方向。经250℃沉积且550℃后退火的三氧化钨薄膜，其结晶度提升幅度与光电流响应均为最优：在0.1 M高氯酸电解液中、相对于Ag/AgCl参比电极的1.6 V电位下，经AM 1.5光谱（100 mW/cm²）的太阳能模拟器辐照时，光电流密度可达1.9 mA/cm²；在369 nm波长、正面辐照条件下，IPCE值为0.5，该性能可与其他沉积工艺（如水热法或溶胶-凝胶法）制备的样品相媲美。喷雾热解法作为制备三氧化钨光电极的工艺，其优势在于可制备适用于实际应用的大面积光电极。