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Self‐Biasing Photoelectrochemical Cell for Spontaneous Overall Water Splitting under Visible‐Light Illumination
Author(s) -
Chen Quanpeng,
Li Jinhua,
Li Xuejin,
Huang Ke,
Zhou Baoxue,
Shangguan Wenfeng
Publication year - 2013
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201200936
Subject(s) - photocathode , water splitting , materials science , optoelectronics , visible spectrum , biasing , light intensity , photoelectrochemical cell , fermi level , open circuit voltage , band bending , photochemistry , optics , chemistry , electrode , voltage , electron , photocatalysis , electrolyte , physics , catalysis , biochemistry , quantum mechanics
A self‐biasing photoelectrochemical (PEC) cell that could work for spontaneous overall water splitting in a neutral solution was established based on the mismatched Fermi levels between the photoelectrodes. A Pt‐catalyst‐decorated crystalline silicon photovoltaic cell (Pt/PVC) was prepared and employed as an effective photocathode. This was coupled with a poly(ethylene glycol)‐directed WO 3 /W photoanode prepared by a hydrothermal process. Both of the photoelectrodes showed a response to visible light. The WO 3 /W photoanode had a positively located valence band edge, the energy level of which was enough for water oxidation, and the Pt/PVC photocathode possessed a negatively located conduction band edge, which was capable of water reduction. More importantly, the Fermi level of the WO 3 /W photoanode was more positive than that of the Pt/PVC photocathode because of the p–n junction of the PVC that decoupled the band bending and enlarged the photovoltage. Under visible‐light irradiation, the WO 3 /W photoanode provided a negative bias for the Pt/PVC photocathode, and the Pt/PVC photocathode provided a positive bias for the WO 3 /W photoanode. An interior bias was generated that could relax the strict criteria of overall water splitting by cooperatively separating the hole–electron pairs at both photoelectrodes. In this system, the short‐circuit current and the open‐circuit voltage increased with increasing light intensity (AM 1.5 illumination) to reach 121 μA cm −2 and 0.541 V, respectively, at a light intensity of 100 mW cm −2 . Such a combination provides a promising method for the fabrication of self‐driven devices for solar‐energy storage.