Layered Ni2P–Fe2P–Co2P Nanoarrays as a Bifunctional Electrocatalyst for Highly Efficient Overall Alkaline Water Splitting

The creation of electrocatalysts composed of nonprecious metals, which must be efficient, durable, and economical, constitutes a major scientific hurdle for achieving practical overall water splitting (OWS). In this study, a layered Ni 2 P–Fe 2 P–Co 2 P nanoarray electrocatalyst was fabricated on nickel foam (NF) using NiFeCoOH via electrodeposition followed by a low-temperature phosphidation strategy. The electrocatalyst features abundant in-plane heterojunctions formed via cation exchange, which effectively tune its morphology and enhance charge-transfer efficiency and active-site exposure. At the same time, the heterojunctions promote the adsorption/desorption of reaction intermediates, thereby synergistically enhancing the catalytic activity for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). In an alkaline electrolyte, the catalyst requires low overpotentials of only 43 mV for HER and 259 mV for OER to deliver a current density of 10 mA cm –2 and demonstrates excellent durability. When employed for overall water splitting, it achieves 10 mA cm –2 at a low cell voltage of 1.43 V.