Visible light active pristine and Fe3+Fe3+ doped CuGa2O4CuGa2O4 spinel photocatalysts for solar hydrogen production

Spinel metal oxide photocatalysts, a rarely studied group in visible light driven photocatalytic decomposition of H2SH2S and solar H2H2 production, have been investigated in the present work. d10d10 p-block element, Ga containing spinel CuGa2O4CuGa2O4 in pristine and Fe3+Fe3+doped (CuGa2-xFexO4CuGa2-xFexO4, x=0.6x=0.6) states, was prepared by ceramic route without/with noble metal oxide, NiO/RuO2NiO/RuO2 loading to the extent of 1 wt%. XRD analysis reveals a single-phase cubic spinel crystalline structure for all the catalysts. FESEM displays an irregular-shaped grain morphology for CuGa2O4CuGa2O4 and smaller size almost cubic particles for CuGa2-xFexO4CuGa2-xFexO4. Energy dispersive X-ray spectroscopy suggests a chemical composition consistent with the stoichiometric molecular formula. Optically, the catalysts display an intensive light absorption in UV and visible regions with an onset at about 900 nm in the near IR region. Fe3+Fe3+ doping constructively influences the morphology and optical properties of pristine CuGa2O4CuGa2O4. All these physico-chemical and material characteristics infuse a facile catalytic function into the prepared spinel oxides such that the naked CuGa2O4CuGa2O4 and CuGa2-xFexO4CuGa2-xFexO4 spinels exhibit a moderate to fairly good photocatalytic activity while the co-catalyst-loaded CuGa2-xFexO4CuGa2-xFexO4 spinel performs an exceedingly good photocatalytic activity with 15% quantum efficiency. Thus, the present work leads to the emergence of functionally high performance, stable and visible active (λ⩾420nm) photocatalysts in the spinel group for the production of solar hydrogen from H2SH2S.