Promoting the electrocatalytic oxygen evolution reaction on NiCo2O4 with infrared-thermal effect: A strategy to utilize the infrared solar energy to reduce activation energy during water splitting

Utilization of the infrared (IR) solar energy remains a challenging task for traditional photo(electro)catalysis. Taking advantage of the IR-thermal effect to facilitate sluggish electrocatalytic reactions emerges as a promising way to utilize the IR band of the solar spectrum. In this work, nickel foam (NF) supported NiCo₂O₄ nanoneedles (NF/NiCo₂O₄ NNs) were prepared to promote the oxygen evolution reaction (OER) via the IR-thermal effect, with the NF/NiCo₂O₄ NNs acting as both the IR absorbing antennae and the OER active anode. The potential required to deliver a current density of 200 mA cm^-2 is negatively shifted from 1.618 V in the dark to 1.578 V under IR irradiation, and the Tafel slope is also decreased from 106 to 89 mV dec^-1. We demonstrate that the enhancement of OER activity is due to the localized temperature rise under IR irradiation. We measured the electrochemical activation energy of OER on NF/NiCo₂O₄ with and without IR irradiation, and the results reveal that IR irradiation reduces the kinetic energy barrier of the OER by IR-thermal effect and then facilitates OER kinetics. This work highlights a new approach to utilizing the IR portion of the sunlight to produce renewable hydrogen energy via water splitting.