N+-ion irradiation engineering towards the efficient oxygen evolution reaction on NiO nanosheet arrays

Abstract

The oxygen evolution reaction (OER) is an essential process in water splitting, which is highly relevant to the new generation of energy exploration approaches. As an electrochemical catalyst for the OER, NiO has been extensively investigated in the past. However, due to its relatively poor conductivity, improving the electrocatalytic performance of NiO-based catalysts in the OER remains a challenge. Herein, we performed density functional theory (DFT) calculations and found that native oxygen vacancies and N-dopants could narrow the band gap of NiO, improving its conductivity for charge transference during the OER process. Therefore, we simultaneously introduced oxygen vacancies and N-dopants into NiO nanosheets by N⁺-ion irradiation (dose of 5 × 10¹⁵ ions per cm²), improving the OER electrocatalytic performance of NiO, and reducing the potential vs. a reversible hydrogen electrode (RHE) of NiO from 2.32 V to 1.98 V at a current density of 100 mA cm⁻². This research provides a new strategy to enhance the OER electrocatalytic capacity of NiO nanosheets, creating a promising catalyst for water splitting in the future.