Enabling small band-gap semiconductors for solar water oxidation using multifunctional NiOx coating

Abstract

Technol. important small band gap (< 2 eV) semiconductors must be stabilized against corrosion or passivation in aq. electrolytes before they can be used as photoelectrodes that directly produce fuels from sunlight. In addn., incorporation of electrocatalysts on the surface of the photoelectrodes is required for efficient oxidn. of H_2O to O_2(g) and redn. of H_2O or H_2O and CO_2 to fuels. Stabilization of technol. important semiconductors against photocorrosion and photopassivation would have a significant impact on photoelectrochem. energy conversion, and could enable the development of a new generation of robust integrated devices for efficient solar-driven water splitting and solar-driven CO_2 redn. Previous efforts have been extensively dedicated on elongating the lifetime of semiconductors under harsh fuel forming reaction conditions esp. during the water oxidn. half reaction. To date, the energy conversion performances and stability were limited on these systems, obscuring the realization of integrated solar fuel devices. In this work, we presented our recent effort on prepn. of a multifunctional coating using Ni oxide, which provides multiple important functions on semiconductor photoelectrodes surfaces, including chem./corrosion protection, elec. conducting, optical transparent/antireflective, and inherent electrocatalytic activity.