Light-induced water oxidation by polymorphs of the Zn–Co–Ni oxide spinel catalyst: a comparative study

Abstract

Spinel-type cobalt substituted Zn_0.2Ni_0.8Co₂O₄ exhibits high activity and stability for the oxygen evolution reaction. The two different dimensions (1D and 3D) of Zn_0.2Ni_0.8Co₂O₄ were explored in the photochemical water oxidation reaction. The 3D highly porous microspheres (MPS) were catalytically more active compared to the mesoporous 1D rods (MPR). The MPS form shows high turnover numbers than that of the MPR under similar experimental conditions. After each oxidation reaction, both the catalysts MPR and MPS (1D and 3D) were characterized and it was proved that the compounds were stable after the catalytic cycle. Further, it was found that the catalysts could be reused and recycled for several catalytic cycles. Hence, these simple catalysts Zn_0.2Ni_0.8Co₂O₄ (1D and 3D) could be proposed for application in artificial photosynthesis, as they work efficiently in the light-driven water oxidation process. Zn–Ni–Co oxide was explored for the first time as a catalyst in the water oxidation reaction.