Ni-Fe-P/Co-W: Nested heterostructures and multi-transition metal synergistic effect optimizing overall water splitting performance

Recently, the application of multi-component transition alloy catalysts in the water splitting field has been a popular development trend. In this work, we have proposed a multi-alloy catalyst for in-situ synthesis of nested multilayer heterostructure Co-W on Ni-Fe-P by electrodeposition way. The heterogeneous interfaces brought by the nested heterogenous structure expose abundant active sites on the catalyst, effectively enhancing the catalytic performance. Moreover, the synergistic effect of five elements (Ni, Fe, P, Co, and W) in the electrocatalysts improves electron transfer efficiently. By adjusting the proportion of Co and W of Co-W-O in the Ni-Fe-P plating solution, we have obtained optimal electrochemical performance in 1 M KOH solution. At 150 (10) mA cm−2, the HER and OER overpotentials are 157.6 (23.6) mV and 260.6 (219.9) mV respectively. Furthermore, it shows a low cell voltage (1.46 V) in overall water splitting, exceeding most of the previously reported electrocatalysts. The activity of Ni-Fe-P/Co-W has no significant decrease at 100 mA cm−2 for 100 h. Subsequently, XPS and Raman spectroscopy are used to infer the mechanism of the electrochemical reaction. This study demonstrates a kind of simple, scalable, and efficient bifunctional electrocatalyst method that has special nested heterogenous structure for overall water splitting.