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

Spinel metal oxide photocatalysts, a rarely studied group in visible light driven photocatalytic decomposition of H 2 S and solar H 2 production, have been investigated in the present work. d 10 p-block element, Ga containing spinel CuGa 2 O 4 in pristine and Fe 3 + doped ( CuGa 2 - x Fe x O 4 , x = 0.6 ) states, was prepared by ceramic route without/with noble metal oxide, NiO / RuO 2 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 CuGa 2 O 4 and smaller size almost cubic particles for CuGa 2 - x Fe x O 4 . 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. Fe 3 + doping constructively influences the morphology and optical properties of pristine CuGa 2 O 4 . All these physico-chemical and material characteristics infuse a facile catalytic function into the prepared spinel oxides such that the naked CuGa 2 O 4 and CuGa 2 - x Fe x O 4 spinels exhibit a moderate to fairly good photocatalytic activity while the co-catalyst-loaded CuGa 2 - x Fe x O 4 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 ⩾ 420 nm ) photocatalysts in the spinel group for the production of solar hydrogen from H 2 S .