NiCoP coated on NiCo2S4 nanoarrays as electrode materials for hydrogen evolution reaction

It is very important to exploit robust electrocatalysts for the urea splitting in an alkaline medium. Hence, the NiCo2S4@NiCoP nanoarrays on Ni foam (NiCo2S4@NiCoP/NF) was successfully synthesized for the first time and used as an efficient and stable difunctional electrocatalyst for the overall urea splitting. As one of the most promising bifunctional electrocatalysts reported, NiCo2S4@NiCoP only needs 108 mV to reach current density of 10 mA cm−2 for hydrogen evolution reaction. Moreover, such NiCo2S4@NiCoP//NiCo2S4@NiCoP electrodes couple display superior urea splitting performance with the requirement of a cell voltage of 1.53 V to drive a catalytic current density of 10 mA cm−2. In addition, the NiCo2S4@NiCoP material presents high long-term electrocatalytic stability keeping its performance at 11 mA cm−2 for 12 h. The experimental results demonstrate that the sluggish Volmer step has been improved by incorporating the NiCoP to the NiCo2S4.