Core-branch CoNi hydroxysulfides with versatilely regulated electronic and surface structures for superior oxygen evolution electrocatalysis

To satisfy the rapid development of gas-involving electrocatalysis (O2, CO2, N2, etc.), nanostructured electrocatalysts with favorably regulated electronic structure and surface nanostructures are urgently required. Herein, we highlighted a core-branch hydroxysulfide as a significantly enhanced oxygen evolution reaction electrocatalyst. This hydroxysulfide was facilely fabricated via a versatile interfacial reaction in S2− inorganic solution at room temperature for a designed period. The moderative growth kinetics contributed to the growth of interconnected hydroxysulfide nanosheets with high-sulfur contents on the hydroxide precursor substrates, resulting in a hierarchical nanostructure with multifunctional modifications, including regulated electronic structure, rapid electron highway, excellent accessibility, and facilitated mass transfer. Such synthetic methodology can be generalized and facilely governed by regulating the temperature, concentration, duration, and solvent for targeted nanostructures. Contributed to the favorably regulated electronic structure and surface nanostructure, the as-obtained core-branch Co2NiS2.4(OH)1.2 sample exhibits superior OER performance, with a remarkably low overpotential (279 mV required for 10.0 mA cm−2), a low Tafel slope (52 mV dec−1), and a favorable long-term stability. This work not only presents a promising nanostructured hydroxysulfide for excellent OER electrocatalysis, but also shed fresh lights on the further rational development of efficient electrocatalysts.