N-carbon supported hierarchical Ni/Ni0.2Mo0.8N nanosheets as high-efficiency oxygen evolution electrocatalysts

Abstract Rational development of high-performance and cost-effective electrocatalysts for the oxygen evolution reaction (OER) is of particular importance for renewable energy conversion and storage technologies. Herein, we developed a facile and easily scalable hard-template strategy to fabricate hierarchical Ni/Ni0.2Mo0.8N nanosheets (~4.37 nm in thickness) in situ coupled with N-doped carbon (Ni/Ni0.2Mo0.8N@N-C) as an efficient electrocatalyst for the OER. The elaborate construction of Ni/Ni0.2Mo0.8N can validly regulate the electronic structure, increase the number of active sites, and facilitate diffusion kinetics. Benefiting from the coupling effect between hierarchical Ni/Ni0.2Mo0.8N and the N-carbon matrix, the resultant Ni/Ni0.2Mo0.8N@N-C exhibits excellent OER performance in alkaline media, including a low overpotential of 260 mV at 10 mA cm−2, a small Tafel slope of 46 mV dec−1, as well as remarkable stability for long-term electrolysis operation, significantly exceeding the findings for most previously reported OER electrocatalysts. Theoretical studies demonstrate that incorporation of Ni into Ni0.2Mo0.8N can effectively optimize water adsorption energy and enhance electronic states density near the Fermi level, which is conducive to accelerating the OER process. This work underlines a rational and new perspective for designing inexpensive and robust Mott-Schottky electrocatalysts toward OER for energy storage and conversion devices.