CoO/NiFe LDH heterojunction as a photo-assisted electrocatalyst for efficient oxygen evolution reaction

Abstract

Photo-assisted electrocatalysis is a frontier direction of electrocatalysis in recent years, which is based on the synergistic effects of electrical and optical energy, providing a new strategy to improve the oxygen evolution reaction (OER) performance. The development of photo-assisted electrocatalysts for OER with high activity and long-term stability is of great significance for hydrogen production through water splitting. In this work, the CoO/NiFe LDH heterojunction are prepared as a photo-assisted electrocatalysts for the first time to enhance OER performance. The strong electron coupling between CoO and NiFe LDH is beneficial to change the electronic structure of catalyst and promote OER. Meanwhile, under illumination, NiFe LDH suppresses the photogenerated charge recombination of CoO and accelerates the charge transfer to promote the accumulation of holes in the CoO valence band, which can be used to further improve its OER performance. The CoO/NiFe LDH requires only an overpotential of 230 mV to achieve 10 mA cm−2 under illumination, which is 60 mV lower than that without irradiation. For water splitting, CoO/NiFe LDH heterojunction only requires 1.57 V (without light) and 1.52 V (with light) to achieve 10 mA cm−2, which is superiors to RuO2 and most NiFe LDH based materials. Even under the irradiation of low-power LED strip, the CoO/NiFe LDH can still exhibit excellent water splitting performance and long-term stability. This work adopts a promising photo-assisted electrocatalytic strategy to promote the efficiency of water splitting, and boosts the development of LDH-based two-dimensional materials in the field of photo-assisted electrocatalysis.