Hierarchical FeNiP@Ultrathin Carbon Nanoflakes as Alkaline Oxygen Evolution and Acidic Hydrogen Evolution Catalyst for Efficient Water Electrolysis and Organic Decomposition.

Efficiency of hydrogen evolution via water electrolysis is mainly impeded by the kinetically sluggish oxygen evolution reaction (OER). Thus, it is of great significance to develop highly active and stable OER catalyst for alkaline water electrolysis or to substitute the more kinetically demanding acidic OER with a facile electron-donating reaction such that OER is no longer the bottleneck half-reaction for either acidic or alkaline water electrolysis. Herein, the hierarchical Fe-Ni phosphide shelled with ultrathin carbon networks on Ni foam (FeNiP@C) is reported and shows exceptional OER activity and enhanced chemical stability in 1 M KOH. This unique electrode provides large active sites, facile electron transport pathways, and rapid gas release, resulting in a remarkable OER activity that delivers a current density of 100 mA/cm2 at an overpotential of 182 mV with a Tafel slope of 56 mV/dec. Combining the hydrogen evolution reaction with organic pollutant (methylene blue) oxidation, a multifunctional electrolyzer for simultaneous cost-effective hydrogen generation and organic pollutant decomposition in acid wastewater is proposed. Our strategies in this work provide attractive opportunities in energy- and environment-related fields.