title: Forming buried junctions to enhance the photovoltage generated by cuprous oxide in aqueous solutions.
abstract: Whereas wide-bandgap metal oxides have been extensively studied for the photooxidation of water, their utilization for photoreduction is relatively limited. An important reason is the inability to achieve meaningful photovoltages with these materials. Using Cu2 O as a prototypical photocathode material, it is now shown that the photovoltage barrier can be readily broken by replacing the semiconductor/water interface with a semiconductor/semiconductor one. A thin ZnS layer (ca. 5 nm) was found to form high-quality interfaces with Cu2 O to increase the achievable photovoltage from 0.60 V to 0.72 V. Measurements under no net exchange current conditions confirmed that the change was induced by a thermodynamic shift of the flatband potentials rather than by kinetic factors. The strategy is compatible with efforts aimed at stabilizing the cathode that otherwise easily decomposes and with surface catalyst decorations for faster hydrogen evolution reactions. A combination of NiMo and CoMo dual-layer alloy catalysts was found to be effective in promoting hydrogen production under simulated solar radiation.
authors.affiliation: Department of Chemistry, Merkert Chemistry Center, Boston College, 2609 Beacon St., Chestnut Hill, MA 02467 (USA); Key Laboratory for Colloid and Interface Chemistry of Education Ministry, Shandong University, 27 South Shanda Road, Jinan, Shandong, 250100 (P.R. China).
authors.forename: Pengcheng
authors.initials: P
authors.lastname: Dai
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.forename: Jin
authors.initials: J
authors.lastname: Xie
authors.forename: Yumin
authors.initials: Y
authors.lastname: He
authors.forename: James
authors.initials: J
authors.lastname: Thorne
authors.forename: Gregory
authors.initials: G
authors.lastname: McMahon
authors.forename: Jinhua
authors.initials: J
authors.lastname: Zhan
authors.forename: Dunwei
authors.initials: D
authors.lastname: Wang
keywords: cuprous oxide; hydrogen; photoelectrochemistry; solar energy conversion; water splitting