物理化学学报 >> 2015, Vol. 31 >> Issue (10): 1895-1904.doi: 10.3866/PKU.WHXB201509074

电化学和新能源 上一篇    下一篇

表面钒修饰对α-Fe2O3材料光电化学性能的增强作用

姚利珍,孔德生*(),杜玖瑶,王泽,张经纬,王娜,李文娟,冯媛媛   

  • 收稿日期:2015-07-10 发布日期:2015-10-10
  • 通讯作者: 孔德生 E-mail:kongdscn@eyou.com
  • 基金资助:
    山东省自然科学基金(ZR2010EM026);国家级大学生创新创业训练计划项目(201410446044)

Enhancement of the Photoelectrochemical Activity of α-Fe2O3 Materials by Surface Modification with Vanadium

Li-Zhen. YAO,De-Sheng. KONG*(),Jiu-Yao. DU,Ze. WANG,Jing-Wei. ZHANG,Na. WANG,Wen-Juan. LI,Yuan-Yuan. FENG   

  • Received:2015-07-10 Published:2015-10-10
  • Contact: De-Sheng. KONG E-mail:kongdscn@eyou.com
  • Supported by:
    the Natural Science Foundation of Shandong Province, China(ZR2010EM026);National Training Programs ofInnovation and Entrepreneurship for Undergraduates, China(201410446044)

摘要:

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.

关键词: 水分解, 光生电荷传输, 表面复合, 光电流, 交流阻抗谱

Abstract:

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.

Key words: Water splitting, Interfacial charge transfer, Surface recombination, Photocurrent, AC impedance spectroscopy

MSC2000: 

  • O649