Ni2P nanoparticles-inserted NiFeP nanosheets with rich interfaces as efficient catalysts for the oxygen evolution reaction

The development of energy materials possessing large number of active sites and exhibiting increased catalytic performance is an important strategy in (electro)catalysis. In this study, Ni2P/NiFeP owning rich interfaces was fabricated within the Ni(OH)2 nanosheet arrays to form hetero-structured Ni2P/NiFeP catalysts via the Kirkendall effect. The as-prepared catalysts exhibited only 250 mV overpotential towards the oxygen evolution reaction (OER) at + 50 mA cm−2 in alkaline electrolytes, and delivered a current density of + 10 mA cm−2 at 1.57 V in a complete and fully functional water electrolyser using the Ni2P/NiFeP and Ni2P/Ni2P catalysts on the anode and cathode side, respectively. The evolution and reconstruction of the interface in Ni2P/NiFeP during the electrochemical stability test experiments was also studied. It was found that reducing the interface resulted in a decrease in electrocatalytic performance and a transition in crystal structure to amorphous state was observed. The method developed in this investigation has been found to be useful for developing catalysts of rich interfaces, in turns paving the way for integrating novel highly active and stable electrocatalysts in electrochemical water splitting technologies.