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

ABSTRACT: 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 (Ni _x M_1-x O _y ) and their catalytic performance towards OER. Ni _x M_1-x O _y 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 Ni _x M_1-x O _y , the common feature of combusted materials. X-ray diffraction (XRD) of Ni _x M_1-x O _y 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 N₂-physisorption. The electrocatalytic performance of the as-prepared materials was evaluated towards OER in alkaline medium. Among them, Ni _x Co_1-x O _y 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 Ni _x Co_1-x O _y was attributed to the synergism between cobalt and nickel and the alteration of the electronic structure of nickel. Also, Ni _x Co_1-x O _y 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.

SUBMITTER: Abu Hatab AS 

PROVIDER: S-EPMC8978898 | biostudies-literature | 2022 Jan

REPOSITORIES: biostudies-literature