Shen Zhao, Chunyang Wang, Guoqiang Han, Haitao Liu, Guangwen Xie*, Xin Liu**, Luhua Jiang ***

College of Materials Science and Engineering, Qingdao University of Science and Technology, Qingdao, 266042, P.R. China

*Corresponding authors. E-mail: xiegw@qust.edu.cn (G. Xie), liuxin@qust.edu.cn (X. Liu), luhuajiang@qust.edu.cn (L. Jiang)

Abstract:

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 heterostructured Co-W on amorphous Ni-Fe-P by electrodeposition. The heterogeneous interfaces brought by the CoOOH/Ni-W/Ni-Fe-P 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 coating improves electron transfer efficiently. By adjusting the proportion of Co and W in the second phase of Ni-Fe-P plating solution, we have obtained optimal electrochemical performance in 1M KOH solution. At 150 (10) mA cm^-2, the HER, OER, and overall water splitting overpotential are 157.6 mV (23.6 mV), 260.6 mV (219.9 mV) and 2.09 V (1.46 V) respectively. Furthermore, there is no significant decrease in activity of Ni-Fe-P/Co-W at 100mA cm-2 for 100 hours. Subsequently, XPS and Raman spectroscopy have been used to infer the mechanism of the electrochemical reaction. Overall, this study demonstrates a kind of simple, scalable, and efficient method for bifunctional electrocatalysts that has special nested heterogenous structure for overall water splitting.

Keywords: HER/OER; Electrocatalysts; Nested heterogenous structure; Electrochemical water splitting; Ni-Fe-P