title: Self-biasing photoelectrochemical cell for spontaneous overall water splitting under visible-light illumination.
abstract: 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 WO3/W photoanode prepared by a hydrothermal process. Both of the photoelectrodes showed a response to visible light. The WO3/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 WO3/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 WO3/W photoanode provided a negative bias for the Pt/PVC photocathode, and the Pt/PVC photocathode provided a positive bias for the WO3/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.
authors.affiliation: School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, PR China.
authors.forename: Quanpeng
authors.initials: Q
authors.lastname: Chen
authors.forename: Jinhua
authors.initials: J
authors.lastname: Li
authors.forename: Xuejin
authors.initials: X
authors.lastname: Li
authors.forename: Ke
authors.initials: K
authors.lastname: Huang
authors.forename: Baoxue
authors.initials: B
authors.lastname: Zhou
authors.forename: Wenfeng
authors.initials: W
authors.lastname: Shangguan
mesh_terms: D002384:Catalysis; D011211:Electric Power Supplies; D004563:Electrochemistry; D008027:Light; D008029:Lighting; D010087:Oxides / Q000737:chemistry; D055668:Photochemical Processes; D010984:Platinum / Q000737:chemistry; D014414:Tungsten / Q000737:chemistry; D014867:Water / Q000737:chemistry*
chemical_list: D010087:Oxides; D014867:Water; D010984:Platinum; C511604:tungsten oxide; D014414:Tungsten
keywords: electrochemistry; energy conversion; silicon; tungsten; water splitting