%0 Journal Article
%T <br>
%A 冯媛媛
%A 姚利珍
%A 孔德生
%A 张经纬
%A 李文娟
%A 杜玖瑶
%A 王娜
%A 王泽
%J 物理化学学报
%D 2015
%R 10.3866/PKU.WHXB201509074
%X 对半导体材料进行表面化学修饰或改性,是提高其光催化活性、有效利用光能的一种重要措施.本文结合水热化学法、化学池沉积和后续热处理等,分别制备了未修饰α-Fe2O3和钒修饰的α-Fe2O3光电极材料.利用X射线粉末衍射(XRD)谱和紫外-可见漫反射光谱(UV-Vis-DRS)技术分析表征了材料的晶相结构、化学组成和光谱吸收等固体物理化学性能;利用光电流测量和电化学交流阻抗谱(EIS)实验技术,并基于1 mol·L-1NaOH (pH 13.6)中的光电化学水分解反应,研究了钒修饰对α-Fe2O3材料光电化学性能的增强作用.结果表明,与未修饰的Fe2O3材料相比,钒修饰α-Fe2O3样品出现FeVO4的XRD特征峰,但临界光吸收波长未发生红移;钒修饰使Fe2O3材料的光电流增大4-5倍、光生载流子在电极表面的复合几率降低了3/4-4/5、电极表面电荷传递速率(表观一级速率常数)明显提高.结合Fe2O3/溶液界面半导体能带模型和有关研究结果,分析了研究体系的界面电荷动力学传输过程以及钒修饰使α-Fe2O3材料光电化学性能增强的原因.<br>Surface modification of semiconductor materials is an effective way to improve their photocatalysis and photo-conversion activities. Bare and V-modified α-Fe2O3 photoelectrode materials were prepared using hydrothermal, chemical bath deposition and heat treatment approaches. Their physicochemical and photoelectrochemical (PEC) properties were then investigated with X-ray diffractometry (XRD), UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS), voltammetry, and electrochemical AC impedance spectroscopy (EIS) techniques. The existence of FeVO4 was indicated by its characteristic X-ray diffractometry patterns, while no significant red shifts in the photoabsorption edge were detected in UV-Vis diffuse reflectance spectroscopy spectra. With V-modified and bare Fe2O3 serving as a photoanode, photoelectrochemical measurements were carried out for water splitting in 1 molmol·L-1 NaOH (pH 13.6). The enhancement of α-Fe2O3 photoelectrochemical activities through V-modification was indicated by significantly increased photocurrents and decreased photocharge-recombination probability. By measuring electrochemical AC impedance spectroscopy spectra, pseudo-first-order rate constants for the charge transfer at the illuminated electrode/solution interface were estimated. The rate constant for V-modification of the Fe2O3 electrode was higher than that of the bare Fe2O3 electrode. Improved interfacial charge transfer kinetics through V-modification is responsible for the enhanced photoelectrochemical activities of α-Fe2O3. The interfacial photocharge transfer and recombination processes and their properties are discussed with a semiconductor energy band model constructed for the electrode system
%U http://www.whxb.pku.edu.cn/CN/Y2015/V31/I10/1895