Combined nanostructured Bi2S3/TNA photoanode and Pt/SiPVC photocathode for efficient self-biasing photoelectrochemical hydrogen and electricity generation

A good visible light responsive nanostructured Bi2S3/TiO2 nanotube array (TNA) photoanode has been prepared for efficient self-biasing photoelectrochemical (PEC) hydrogen and electricity generation by combining with a Pt/SiPVC photocathode based on the mismatching Fermi levels between photoelectrodes. Under visible-light irradiation, the potential of Bi2S3/TNA photoanode is more negative than that of Pt/SiPVC photocathode, leading to a self-bias (open-circuit voltage V-oc=0.766 V) which can facilitate photogenerated electrons in Bi2S3/TNA to recombine with photogenerated holes in Pt/SiPVC via external circuit. Intensity modulated photocurrent spectroscopy (IMPS) measurements showed that the transit time (tau(d)) was 8.54 ms for photogenerated electrons in Bi2S3/TNA photoanode and 6.42 ms for photogenerated holes in Pt/SiPVC photocathode, both of which were less than that of traditional PEC cells made up of Bi2S3/TNA photoanode and Pt counter-electrode (Bi2S3/TNA-Pt, 22.27 ms) or Pt/SiPVC photocathode and Pt counter-electrode (Pt-Pt/SiPVC, 15.85 ms). This demonstrates an efficient charge transport and low electron-hole recombination rate in the self-biasing PEC cell. In this system, short-circuit current, fill factor, and photoelectric conversion efficiency was 1.55 mA cm(-2), 0.602, and 0.718%, respectively. A H-2 evolution rate of similar to 45.5 mu mol cm(-2) h(-1), which was 141 times larger than Bi2S3/TNA-Pt and 1.8 times larger than Pt-Pt/SiPVC, was also achieved. (C) 2014 Elsevier Ltd. All rights reserved.