title: A Metal-Nitride Nanowire Dual-Photoelectrode Device for Unassisted Solar-to-Hydrogen Conversion under Parallel Illumination.
abstract: A dual-photoelectrode device, consisting of a photoanode and photocathode with complementary energy bandgaps, has long been perceived as an ideal scheme for achieving high efficiency, unassisted solar-driven water splitting. Previously reported 2-photon tandem devices, however, generally exhibit an extremely low efficiency (<0.1%), which has been largely limited by the incompatibility between the two photoelectrode materials. Here we show that the use of metal-nitride nanowire photoelectrodes, together with the scheme of parallel illumination by splitting the solar spectrum spatially and spectrally, can break the efficiency bottleneck of conventional 2-photon tandem devices. We have first investigated a dual-photoelectrode device consisting of a GaN nanowire photoanode and an InGaN nanowire photocathode, which exhibited an open circuit potential of 1.3 V and nearly 20-fold enhancement in the power conversion efficiency under visible light illumination (400-600 nm), compared to the individual photoelectrodes in 1 mol/L HBr. We have further demonstrated a dual-photoelectrode device consisting of parallel-connected metal-nitride nanowire photoanodes and a Si/InGaN nanowire photocathode, which can perform unassisted, direct solar-to-hydrogen conversion. A power conversion efficiency of 2% was measured under AM1.5G 1 sun illumination.
authors.affiliation: Department of Electrical and Computer Engineering, McGill University 3480 University Street, Montreal, Quebec H3A 0E9, Canada.
authors.forename: B
authors.initials: B
authors.lastname: AlOtaibi
authors.affiliation: Department of Electrical and Computer Engineering, McGill University 3480 University Street, Montreal, Quebec H3A 0E9, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Fan
authors.affiliation: Department of Electrical and Computer Engineering, McGill University 3480 University Street, Montreal, Quebec H3A 0E9, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Vanka
authors.affiliation: Department of Electrical and Computer Engineering, McGill University 3480 University Street, Montreal, Quebec H3A 0E9, Canada.
authors.forename: M G
authors.initials: MG
authors.lastname: Kibria
authors.affiliation: Department of Electrical and Computer Engineering, McGill University 3480 University Street, Montreal, Quebec H3A 0E9, Canada.
authors.forename: Z
authors.initials: Z
authors.lastname: Mi
keywords: InGaN; Nanowire; dual-photoelectrode; hydrogen; solar fuels; water splitting