Invigorating the catalytic performance of CoP through interfacial engineering by Ni2P precipitation

Abstract

CoP is a very prospective low-cost candidate for the hydrogen evolution reaction catalyst, but it is still far from substituting noble-metal Pt because of the high Gibbs free energy of hydrogen adsorption. With the help of an isostructural precursor of Co(OH)₂ and Ni(OH)₂, Ni₂P clusters could be inlayed in CoP nanosheets. The extensive interface region between CoP and Ni₂P caused by the lattice mismatch lowers the hydrogen bonding energy. Meanwhile, the boundaries on the surfaces create an opportunity for the CoP and Ni₂P couple to exert a synergistic effect and promote the catalytic activity. The catalyst shows excellent electrochemical activity in acidic, neutral or alkaline solution, and it also has excellent performance for the oxygen evolution reaction. The electrochemical compatibility of the couple makes sure that the catalyst can work stably in a harsh catalysis environment. So, the full cell for electrochemical water splitting with the catalyst on both the anode and the cathode only needs 1.60 V to achieve a current density of 10 mA cm⁻².