General Approach of in Situ Etching and Doping To Synthesize a Nickel-Doped M_xO_y (M = Co, Mn, Fe) Nanosheets Array on Nickel Foam as Large-Sized Electrodes for Overall Water Splitting

Development of non-noble-metal catalysts for overall water splitting with both excellent activity and robust stability has attracted great attention recently. Herein, we reported a facile one-pot and low-temperature synthesis of a Ni-doped Co3O4 ultrathin nanosheets array on Ni foam via in situ etching of H+ from hydrolysis of cobalt chloride and Ni doping released from Ni foam. The as-prepared Ni–Co3O4 nanosheets\Ni foam as large-sized electrodes possessed the low overpotential of 170 mV to achieve a current density of 10 mA cm–2 with a small Tafel slope of 76.9 mV dec–1 and strong catalytic stability in 1.0 M KOH. Furthermore, the as-prepared electrodes showed an efficient bifunctional catalytic activity for OER in alkaline electrolyte. Ni–Co3O4 nanosheets\Ni foam electrodes were used as both cathode and anode to form a two-electrode alkaline water electrolyzer, which only needed a voltage of 1.643 V to afford a water-splitting current density of 10 mA cm–2 in 1.0 M KOH electrolyte. Dramatically, it also can be light-driven by using polycrystalline silicon solar cells. The proposed strategy herein offered great advantages in terms of simple, low-cost, low-temperature operation and ease of scale-up, which was also a common method for synthesizing Ni-doped metal oxide electrocatalysts.