Fluorine-Induced Dual Defects in Cobalt Phosphide Nanosheets Enhance Hydrogen Evolution Reaction Activity
Kun Xu, Yiqiang Sun, Xiuling Li, Zihan Zhao, Yongqi Zhang, Cuncheng Li, Hong Jin Fan
Abstract
Introduction of defects in a controllable way is important to modulate the electronic structure of catalysts toward enhancement of electrocatalytic activity. Herein we report that incorporation of fluorine into a cobalt phosphide alloy has a unique effect: it creates both F– anion doping and P vacancies, resulting in a nearly 15-fold enhancement of the catalytic activity for the hydrogen evolution reaction (HER) in neutral solution. The existence of dual defects in CoP was confirmed by extended X-ray absorption fine structure (EXAFS) curve fitting results and density functional theory calculations. We show that the dual-defect feature is beneficial for increasing the active-site exposure, tuning the surface wettability, and optimizing the electronic configuration of CoP for the HER. Our fluorine-based modulation protocol may be applicable to other metal alloy electrocatalysts toward more efficient energy conversion reactions.