Factors affecting the production of H2 by water splitting over a novel visible-light-driven photocatalyst GaFeO3

A d10 photocatalyst, GaFeO3 having a band gap of ∼2.7 eV, exhibits significant activity for the overall splitting of water under visible light (>395 nm) irradiation, in the absence of sacrificial reagent or a noble metal co-catalyst. The doping of an anion led to considerable enhancement in activity, the S-doped catalysts displaying better activity compared to the samples containing nitrogen. Even though the H2/O2 yields were affected by preparation-dependent grain morphology, no direct relationship was observed between the photoactivity of a sample and its specific surface area. The techniques of HRTEM, SEM, XPS, Laser Raman, UV–visible and photoluminescence spectroscopy have enabled to demonstrate that, besides the grain morphology, certain lattice imperfections and microstructure may also play a crucial role in water splitting activity of a photocatalyst. The factors responsible for catalyst deactivation are examined.

► GaFeO3 is a visible-light sensitive photocatalyst for overall water splitting.
► The S-doped GaFeO3 displays better photoactivity for H2 evolution.
► The water splitting activity depends on grain morphology and microstructure.
► The origin of the catalyst deactivation has been examined.