NiO‐Decorated Antimony‐Doped Tin Oxide as an Advanced Binder‐Free Porous Catalyst for Efficient Photoelectrochemical Water Oxidation

Achieving efficient photoelectrochemical oxygen evolution reaction (OER) is a key to reduce the high overpotential barriers associated with overall water splitting. The OER performance of many semiconducting metal oxide catalysts is hindered by weak charge separation at the interface, fast carrier recombination, low electrical conductivity, and lack of adsorption properties. A promising approach to overcome these issues is the integration of OER catalysts with porous and highly conductive semiconductor templates. However, the strategic selection of the template is important to facilitate the formation of heterojunction, which can promote effective carrier transport and boost photoelectrochemical performance. Herein, a novel binder‐free photoelectrocatalyst for efficient alkaline water oxidation is reported. This catalyst is developed through an in situ incorporation of OER active nickel oxide (NiO) catalyst into a porous, conductive antimony‐doped tin oxide (ATO) semiconductor using a resorcinol‐formaldehyde polymer supported sol–gel method. The prepared NiO/ATO binder‐free porous catalyst exhibits greatly improved photoelectrochemical performance toward water oxidation with a remarkable low onset potential of 1.39 V and an overpotential of 282 mV (at 10 mA cm −2 ). This significant enhancement of OER performance is due to improved charge transport properties at the NiO/ATO heterojunction and increased surface area with more active catalytic sites.