Modulating Electronic Structure of Cobalt Phosphide Precatalysts via Dual-Metal Incorporation for Highly Efficient Overall Water Splitting

Electrochemical water splitting is a promising strategy to generate highly purified molecular hydrogen (H-2) without any pollutants, but several challenges have impeded its large-scale application because of the lack of low-cost and highly efficient electrocatalysts. Here, the cobalt phosphide (CoP) as an ideal candidate was synthesized for the catalyzed hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline electrolytes, where the incorporation of dual-metal species (W and Fe) was further used to modulate the electronic structure of the pristine CoP nanosheets to accelerate the electrocatalytic kinetics. As expected, the trimetallic phosphide W,Fe@CoP/CNTs catalyst shows remarkable electrocatalytic performances in terms of small overpotentials of 130 mV for HER and 290 mV for OER and superior stabilities for more than 18 h. It is worth noting that the electro-derived self-reconstruction happened to generate the true catalytically active sites, which results in the cobalt oxy/hydroxides after the OER process and metallic cobalt species after the HER process. This work highlights a rational design of phosphide-based electrocatalysts via the incorporation of multimetal species, which could facilitate the oxidation and reduction of as-prepared catalyst and enhance the performances in the electro-derived processes.