Uniform W-NiCoP microneedles by molten salt decomposition as bifunctional electrocatalyst for alkaline water splitting

Abstract Transition metal phosphides (TMPs) owing to the unique Pt-like electron structure have been used as electrocatalysts for hydrogen evolution reaction (HER). Facile metal doping especially high valence metal is an effective strategy but a big challenge for improving HER performances of TMPs. Herein, a simple and mild molten salt decomposition followed by phosphorization method is adopted to obtain W-NiCoP microneedles uniformly distributed on nickel foam (W-NiCoP/NF) with multisite for alkaline HER. The prepared NiCo/NF as precursor assisted by molten salt method can provide the homogenous dispersion and uniform needles arrays, which are also helpful for the interaction with W elements. Notably, W doping could effectively regulate the electronic structure of NiCoP, contributing to enriched electrocatalytic active sites and accelerated Volmer step. As a result, the optimized W-NiCoP/NF only requires 113.7 mV and 295.1 mV to reach 100 mA cm−2 for alkaline HER and oxygen evolution reaction (OER), even outperforming Pt/C and RuO2. The electrocatalyst remains stable after 5000 cycling stability. Therefore, this work based on molten salt decomposition may provide insights for the simple synthesis of efficient bifunctional electrocatalysts for alkaline HER and OER.