Electrodeposited amorphous cobalt phosphosulfide on Ni foams for highly efficient overall water splitting

Abstract

The surface self-reconstruction during the water splitting is considered as one key factor for the high catalytic activity. Owing to the exposure of more dangling bonds, amorphous structure is the ideal precursor to convert into the actual active phase in the process of electrocatalysis. Herein, amorphous cobalt phosphosulfide electrocatalysts are fabricated by a facile electrodeposition method on nickel foams as efficient bifunctional electrodes for overall water splitting. And benefited from the introduction of phosphorus and sulfur, the quantities of precursor sites are increased and the electronic state around cobalt is reconstructed, which provides more active phases and facilitates the transport efficiency of electrons. Electrochemical test results reveal that, the as-prepared cobalt phosphosulfide electrodes require overpotentials as low as 58 and 283 mV to achieve 10 mA cm−2 for hydrogen and oxygen evolution reactions in 1.0 M KOH, respectively. Tafel slopes and electrochemical impedance spectroscopy further illustrate a favorable kinetic during electrolysis. Meanwhile, it only requires a low cell voltage of 1.6 V for cobalt phosphosulfide electrodes to reach 10 mA cm−2 for overall water splitting.