Optimized electroless deposition of NiCoP electrocalysts for enhanced water splitting

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 % (Ni0.83Co0.17P) to maximize OER performance. Impressively, the Ni0.83Co0.17P 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 Ni0.83Co0.17P/NF demonstrates excellent long-term stability as inferred by continuous test for 25 h. Furthermore, a full alkaline electrolyzer is designed using Ni0.83Co0.17P/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.