Acta Phys. -Chim. Sin. ›› 2015, Vol. 31 ›› Issue (10): 1895-1904.doi: 10.3866/PKU.WHXB201509074

• ELECTROCHEMISTRY AND NEW ENERGY • Previous Articles     Next Articles

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)

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