Electrolessly Deposited Cobalt–Phosphorus Coatings for Efficient Hydrogen and Oxygen Evolution Reactions

Hydrogen production by water splitting is one of the low-cost green hydrogen production technologies. The challenge is to develop inexpensive and highly active catalysts. Herein, we present the preparation of electrocatalysts based on cobalt-phosphorus (Co-P) coatings with different P contents for hydrogen and oxygen evolution reactions (HER and OER). The Co-P coatings were deposited on the copper (Cu) surface using the inexpensive and simple method of electroless metal deposition. The morphology, structure, and composition of the Co-P coatings deposited on the Cu surface were studied by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), while their activity for HER and OER in 1 M KOH was investigated by linear sweep voltammetry (LSVs) and chrono-techniques. It was found that the catalyst activity for both HER and OER depends on the P content of the catalyst and varies to the highest efficiency for each reaction. The Co-P coating with the 11 wt% of P exhibited the lowest overpotential value of –115.4 mV for the HER to obtain a current density of 10 mA cm-2 compared to the Co-P coatings with 8 wt% (–121.5 mV) and 5 wt% (–182.9 mV) of P. In contrast, the lowest OER overpotential (394 mV) was observed for the Co-P coating with the 8 wt% of P to obtain a current density of 10 mA cm-2 as compared to the Co-P coatings with 5 wt% (416 mV) and 11 wt% (432 mV) of P. These results suggest that the obtained catalysts are suitable for HER and OER in alkaline media.