Arrays of GaAs nanowires have been grown by selective-area metal-organic chemical-vapor deposition (MOCVD) onto photoactive planar Si substrates. This tandem, vertical-wire-array-on-planar absorber was then coated by atomic layer deposition (ALD) of an amorphous TiO2 (a-TiO2) stabilization layer, followed by deposition of a NiOx electrocatalyst layer. The tandem planar Si/nanowire GaAs/a-TiO2/NiOx photoanodes exhibited continuous solar-driven water oxidation in 1.0 M KOH(aq) for over 600 h without substantial photocurrent decay. The preservation of the nanowire morphology and structural integrity during >600 h of photoanodic operation confirms the benefits of mitigating and isolating nanoscale defects via the architecture of discretized absorbers on a self-passivating and insulating substrate. Nanoscale morphology and compositions of the photoanode after 600 h of testing were characterized to reveal the self-limiting corrosion behavior. It provides a promising approach to develop efficient but otherwise unstable absorbers such as III-V materials into defect-tolerant, corrosion-resistant photoanodes.
ASJC Scopus subject areas
- Chemistry (miscellaneous)
- Renewable Energy, Sustainability and the Environment
- Fuel Technology
- Energy Engineering and Power Technology
- Materials Chemistry