光电沉积Co-Pi对Ta_3N_5水分解性能的影响及机理

Effect and Mechanism of Co-catalyst Co-Pi Impregnation by Light Assisted Electrodeposition on Solar Water Splitting Properties of Ta_3N_5 Photoanodes

Co-Pi是一种低廉高效的氧化水产氧助催化剂,助催化剂担载方法及条件是光阳极太阳能水分解效率提升的关键因素之一。以光阳极材料Ta_3N_5为基底,针对光电沉积担载助催化剂Co-Pi开展了一系列研究,研究表明光电沉积Co-Pi过程中,照射光强的影响较小,而外加偏压和担载电量的影响很大,是Co-Pi担载的关键因素;通过阻抗谱测试定量分析了Co-Pi担载条件对Ta_3N_5/电解液界面载流子输运的影响,表明Co-Pi担载电压和电量直接影响界面光生载流子的传输,进而决定了Ta_3N_5水分解性能的高低;发现最优担载偏压对不同的Ta_3N_5均适用,而最优担载电量和光阳极的表面粗糙度存在正相关关系,要针对光阳极表面粗糙度调节助催化剂担载条件。

Co-Pi is a cheap and high efficient co-catalyst for water splitting. The impregnation method of cocatalyst is very important for water splitting property of photoanode. Therefore, in this work, for Ta3N5 photoanode,a series of studies about co-catalyst Co-Pi impregnation by light assisted electrodeposition have been developed.The results suggest that the incident light intensity during the Co-Pi impregnation process has little effect on the water splitting property, while the loading potential and the loading charge have great influence on the water splitting property of Ta3N5. In addition, the transfer of carriers on Ta3N5/electrolyte interface has been studied by electrochemical impedance spectroscopy test and simulation. The results suggest that the photo-generated carriers transfer can be efficiently regulated by controlling the loading potential and loading charge during the impregnation process to improve the water splitting property of Ta3N5. More importantly, the best loading potential of Co-Pi keeps almost unchanged for Ta3N5 with different roughness, while the best loading charge has positive correlation with the surface roughness of the phtoanode, therefore, the loading charge should be adjusted by the roughness of photoanode.