title: Unbiased photoelectrochemical water splitting in Z-scheme device using W/Mo-doped BiVO4 and Zn(x)Cd(1-x)Se.
abstract: Photoelectrochemical water splitting to generate H2 and O2 using only photon energy (with no added electrical energy) has been demonstrated with dual n-type-semiconductor (or Z-scheme) systems. Here we investigated two different Z-scheme systems; one is comprised of two cells with the same metal-oxide semiconductor (W- and Mo-doped bismuth vanadate), that is, Pt-W/Mo-BiVO4, and the other is comprised of the metal oxide and a chalcogenide semiconductor, that is, Pt-W/Mo-BiVO4 and Zn(0.2)Cd(0.8)Se. The redox couples utilized in these Z-scheme configurations were I(-)/IO3(-) or S(2-)/S(n)(2-), respectively. An electrochemical analysis of the system in terms of cell components is shown to illustrate the behavior of the complete photoelectrochemical Z-scheme water-splitting system. H2 gas from the unbiased photolysis of water was detected using gas chromatography-mass spectroscopy and using a membrane-electrode assembly. The electrode configuration to achieve the maximum conversion efficiency from solar energy to chemical energy with the given materials and the Z-scheme is discussed. Here, the possibilities and challenges of Z-scheme unbiased photoelectrochemical water-splitting devices and the materials to achieve practical solar-fuel generation are discussed.
authors.affiliation: Center for Electrochemistry, Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, TX 78712, USA.
authors.forename: Hyun S
authors.initials: HS
authors.lastname: Park
authors.forename: Heung Chan
authors.initials: HC
authors.lastname: Lee
authors.forename: Kevin C
authors.initials: KC
authors.lastname: Leonard
authors.forename: Guanjie
authors.initials: G
authors.lastname: Liu
authors.forename: Allen J
authors.initials: AJ
authors.lastname: Bard
keywords: Z-scheme system; electrochemistry; photoanodes; semiconductors; water splitting