Optimizing Heterointerface of Co<sub>2</sub>P–Co<sub><i>x</i></sub>O<sub><i>y</i></sub> Nanoparticles within a Porous Carbon Network for Deciphering Superior Water Splitting
Guohe Huang, Miao Hu, Xingtao Xu, Asma A. Alothman, Mohammed Sheikh Saleh Mushab, Shaojian Ma, Pei Kang Shen, Jinliang Zhu, Yusuke Yamauchi
Abstract
It is of great significance to design a bifunctional electrocatalyst for promoting hydrogen (HER) and oxygen (OER) evolution reactions simultaneously. Herein, inspired by the appropriate H atom binding energy on cobalt phosphides and excellent oxygen evolution kinetics on cobalt oxides, the regulative synthesis of a Co 2 P–Co x O y (Co x O y = CoO or Co 3 O 4 ) heterogeneous nanoparticle‐anchored porous carbon network electrocatalyst via one‐pot heat treatment is reported. The as‐synthesized Co 2 P–Co 3 O 4 /C exhibits superior electrochemical activity with low overpotentials of 86 mV for HER and 246 mV for OER at 10 mA cm −2 in an alkaline electrolyte. Moreover, compared to the commercial Pt/C || RuO 2 /C system, the Co 2 P–Co 3 O 4 /C || Co 2 P–Co 3 O 4 /C system presents outstanding activity toward overall water splitting (1.55 V@10 mA cm −2 ), which is well maintained over long‐term (120 h) electrocatalysis. Density functional theory calculations show that the rich interfaces between Co 2 P and Co 3 O 4 offer a synergistic effect, which enables Co 2 P–Co 3 O 4 /C as an excellent electrocatalyst toward both HER and OER.