A highly-efficient oxygen evolution electrode based on defective nickel-iron layered double hydroxide

Exploring efficient and cost-effective electrocatalysts for oxygen evolution reaction (OER) is critical to water splitting. While nickel-iron layered double hydroxide (NiFe LDH) has been long recognized as a promising non-precious electrocatalyst for OER, its intrinsic activity needs further improvement. Herein, we design a highly-efficient oxygen evolution electrode based on defective NiFe LDH nanoarray. By combing the merits of the modulated electronic structure, more exposed active sites, and the conductive electrode, the defective NiFe LDH electrocatalysts show a low onset potential of 1.40 V (vs. RHE). An overpotential of only 200 mV is required for 10 mA cm−2, which is 48 mV lower than that of pristine NiFe-LDH. Density functional theory plus U (DFT+U) calculations are further employed for the origin of this OER activity enhancement. We find the introduction of oxygen vacancies leads to a lower valance state of Fe and the narrowed bandgap, which means the electrons tend to be easily excited into the conduction band, resulting in the lowered reaction overpotential and enhanced OER performance.