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The low efficiency of water electrolysis mostly arises from the thermodynamic uphill oxygen evolution reaction. The efficiency can be greatly improved by rationally designing low-cost and efficient oxygen evolution anode materials. Herein, we report the synthesis of Ni–P alloys adopting a facile electroless plating method under mild conditions on nickel substrates. The relationship between the Ni–P properties and catalytic activity allowed us to define the best conditions for the electroless synthesis of highperformance Ni–P catalysts. Indeed, the electrochemical investigations indicated an increased catalytic response by reducing the thickness and Ni/P ratio in the alloy. Furthermore, the Ni–P catalysts with optimized size and composition deposited on Ni foam exposed more active sites for the oxygen evolution reaction, yielding a current density of 10 mA cm−2 at an overpotential as low as 335 mV, exhibiting charge transfer resistances of only a few ohms and a remarkable turnover frequency (TOF) value of 0.62 s−1 at 350 mV. The present study provides an advancement in the control of the electroless synthetic approach for the design and large-scale application of high-performance metal phosphide catalysts for electrochemical water splitting. [ABSTRACT FROM AUTHOR]

Great scientific effort has strived to develop a low-cost and sustainable electrocatalyst with high electrocatalytic activity and long-term stability in the field of water splitting. In this work non-noble metal based NiCoP alloys are burgeoned from catalytic Ni substrates via a facile and eco-friendly electroless deposition method under mild conditions. By appropriately tuning the cobalt content in the chemical bath, we realize NiCoP coatings with tailored Co concentration. The electrochemical investigations of coatings deposited on flat Ni indicate an optimal Co content of 17 at % (Ni 0.83 Co 0.17 P) to maximize OER performance. Impressively, the Ni 0.83 Co 0.17 P coating deposited on nickel foam exhibits remarkable OER catalytic activity (η = 295 mV at 10 mA cm−2), noteworthy catalytic kinetics (Tafel slope as small as 45 mV dec−1) and high rate of oxygen production for each active site (turnover frequency of 0.16 s−1 at 300 mV) in 1 M KOH. Importantly, the Ni 0.83 Co 0.17 P/NF demonstrates excellent long-term stability as inferred by continuous test for 25 h. Furthermore, a full alkaline electrolyzer is designed using Ni 0.83 Co 0.17 P/NF as the anode and Pt decorated Ni−P/NF as the cathode, which can drive overall water splitting with a potential as low as 1.60 V at 10 mA cm−2, and also shows outstanding long-term durability. The cheapness of the present preparation method as well as its suitability for large-scale production without the need of expensive raw materials and energy-consuming processes paves the way towards commercial production of transition metal phosphide-based electrocatalysts. [Display omitted] • NiCoP alloys were fabricated via a facile and cheap electroless deposition method. • NiCoP coatings with optimized composition showed high OER performance. • The intrinsic catalytic activity was assessed by evaluation of turnover frequency. • An efficient alkaline electrolyzer based on metal phosphides was constructed. [ABSTRACT FROM AUTHOR]