Phosphate-decorated Ni3Fe-LDHs@CoPx nanoarray for near-neutral seawater splitting

Abstract

Direct seawater splitting technique can produce clean hydrogen energy without a complicated water desalination process. However, the oxygen evolution reaction (OER) confronts with selectivity challenge in competing with chlorine evolution and severe corrosion issues of the electrode. In this work, phosphate-decorated Ni3Fe-layered double hydroxides grown on cobalt phosphide nanoarray with both high intrinsic activity and 100 % selectivity towards seawater oxidation in a near neutral electrolyte is reported. The as-prepared electrode shows a low overpotential of 370 mV@10 mA cm−2 with high durability in near-neutral seawater oxidation for 350 h. The phosphate layer on the catalyst surface contributes to the enhanced selectivity by weakening the adsorption of Cl–, and thus avoiding the competing chlorine evolution. Meanwhile, the phosphate layer with a strong proton accepting ability can resist the local pH change on the electrode surface in the neutral electrolyte, affording highly stable seawater splitting for prolonged operations in neutral seawater electrolyte.