Ordered distributed nickel sulfide nanoparticles across graphite nanosheets for efficient oxygen evolution reaction electrocatalyst

Low-cost and earth-abundant nickel chalcogenides with versatilities in electrocatalysis, conversion and storage of energy are hindered in practical application due to the low electrical conductivity and small specific surface area. In the present work, we report a simple preparation of 2D nanocomposites of NiS_x (5 nm) uniformly embedded in several layered graphite (NiS_x@graphite) through the sulfidation of nickel naphtalenedicarboxylic acid framework nanosheets (∼9 nm). The obtained NiS_x@graphite nanosheet composites are used for oxygen evolution reaction (OER) catalysis. Electrochemical studies reveal that their OER activities under strongly alkaline conditions are ranked in the order of Ni₉S₈@graphite > NiS@graphite > NiS₂@graphite. The outstanding OER performance offered by Ni₉S₈@graphite owes to the synergistic effects of large specific surface area and the special structure between nickel sulfide and graphite layer, and the intrinsic large TOFs and the optimal adsorption energy of Ni₉S₈. Furthermore, Ni₉S₈@graphite as an anode material used for lithium ion batteries (LIBs) also shows a high specific capacity with competitive rate performance. Such excellent performance and low price render nickel chalcogenides a promising candidate for the future OER catalyst and LIBs application.