Solution combustion synthesis of Ni-based hybrid metal oxides for oxygen evolution reaction in alkaline medium

Oxygen evolution reaction (OER) has arisen as an outstanding technology for energy generation, conversion, and storage. Herein, we investigated the synthesis of nickel-based hybrid metal oxides (NixM1-xOy) and their catalytic performance towards OER. NixM1-xOy catalysts were synthesized by solution combustion synthesis (SCS) using the metal nitrates as oxidizer and glycine as fuel. Scanning electron microscope (SEM) micrographs display a porous morphology for the hybrid binary NixM1-xOy, the common feature of combusted materials. X-ray diffraction (XRD) of NixM1-xOy depicted well-defined diffraction peaks, which confirms the crystalline nature of synthesized catalysts. The particle size of as-synthesized materials ranges between 20 and 30 nm with a mesoporous nature as revealed by N-2-physisorption. The electrocatalytic performance of the as-prepared materials was evaluated towards OER in alkaline medium. Among them, NixCo1-xOy showed the best catalytic performance. For instance, it exhibited the lowest overpotential at a current density of 10 mA cm(-2) (404 mV), onset potential (1.605 V), and Tafel slope (52.7 mV dec(-1)). The enhanced electrocatalytic performance of NixCo1-xOy was attributed to the synergism between cobalt and nickel and the alteration of the electronic structure of nickel. Also, NixCo1-xOy afforded the highest Ni3+/Ni2+ when compared to other electrocatalysts. This leads to higher oxidation states of Ni species, which promote and improve the electrocatalytic activity.

Automated summary

In this study, nickel-based hybrid metal oxides (NixM1-xOy) were successfully synthesized using solution combustion synthesis method, and their catalytic performance towards OER was evaluated. Among them, NixCo1-xOy exhibited the best catalytic activity for OER. The enhanced performance was attributed to the synergism between cobalt and nickel, as well as the alteration of the electronic structure of nickel.