Visible light active pristine and Fe~(3+) doped CuGa_2O_4 spinel photocatalysts for solar hydrogen production

摘要

Spinel metal oxide photocatalysts, a rarely studied group in visible light driven photocatalytic decomposition of H_2S and solar H_2 production, have been investigated in the present work, d~(10) p-block element, Ga containing spinel CuGa_2O_4 in pristine and Fe~(3+)doped (CuGa_(2-x)Fe_xO_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_2O_4 and smaller size almost cubic particles for CuGa_(2-x)Fe_xO_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_2O_4. All these physico-chemical and material characteristics infuse a facile catalytic function into the prepared spinel oxides such that the naked CuGa_2O_4 and CuGa_(2-x)Fe_xO_4 spinels exhibit a moderate to fairly good photocatalytic activity while the co-catalyst-loaded CuGa_(2-x)Fe_xO_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 ≥ 420nm) photocatalysts in the spinel group for the production of solar hydrogen from H_2S.