A layered Na1−xNiyFe1−yO2 double oxide oxygen evolution reaction electrocatalyst for highly efficient water-splitting

Abstract

Transition metal Ni- and Co-based oxides are potential candidates to replace expensive and scarce noble metal-based oxygen evolution reaction (OER) catalysts such as IrO₂ and RuO₂, which are required for efficient hydrogen production from solar water splitting and rechargeable energy storage technologies. So far, layered NiFe double hydroxide represents the best OER activity among all Ni- and Co-based oxides. Here, we report new layered Na_1−xNi_yFe_1−yO₂ double oxide OER catalysts exhibiting activity and stability surpassing those of noble metal OER catalysts including IrO₂ and RuO₂, and a layered NiFe double hydroxide OER catalyst. The superior catalytic properties can be ascribed to the layered structure as well as the enhanced covalency of Ni and Fe. Powered by a lead halide perovskite solar cell with a power conversion efficiency of 14.69%, a two-electrode solar water-splitting device combining a Na_0.08Ni_0.9Fe_0.1O₂ OER catalyst with a NiP hydrogen evolution reaction catalyst delivers a solar-to-hydrogen conversion efficiency of 11.22%. Our design and fabrication strategies offer insights for developing highly active electrocatalysts for water splitting and metal–air batteries.