Constructing of crystalline CoP/amorphous CoMoP coupling composites for efficient water splitting

Bifunctional electrocatalysts with the joint merits of being highly efficient, stable, and low-cost are essential for overall water splitting applications. Herein, we reported a unique amorphous/crystalline coupling structure consisting of crystalline CoP nanocrystals with amorphous CoMoP in-situ growth on nickel foam (termed as CoP/a-CoMoP/NF). This was achieved through oxidation-phosphating in two successive steps by Keggin-type POM (H 3 PMo 12 O 40 ) embedded into the zeolitic imidazolate framework-67 (ZIF-67) as the precursor. The Mo doping and crystalline/amorphous coupling structures of CoP and CoMoP modulate the electronic structure, increase the electrocatalytic active sites, and promote the interfacial electron transfer , thus accelerating the catalytic kinetics of both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The amorphous CoMoP serves a protective role in preventing corrosion during the electrochemical process . The catalyst exhibits low overpotentials of 301 mV and 250 mV to drive a current of 100 mA cm −2 for OER and HER, respectively, and demonstrates excellent stability for both reactions. Furthermore, the alkaline electrolytic cell assembled with CoP/a-CoMoP/NF catalysts as both the anode and cathode requires only 1.66 V and 1.73 V to drive current densities of 50 and 100 mA cm −2 , respectively. This study offers a rational strategy for the development of efficient bifunctional electrocatalysts for hydrogen generation .