Promoting Oxygen Evolution Reaction of Co-Based Catalysts (Co₃ O₄ , CoS, CoP, and CoN) through Photothermal Effect

The increase of reaction temperature of electrocatalysts is regarded as an efficient method to improve the oxygen evolution reaction (OER) activity. Herein, it is reported that the electrocatalytic performance of dual functional (i.e., electrocatalytic and photothermal functions) Co₃ O₄ can be dramatically improved via its photothermal effect. The operating temperature of the Co₃ O₄ electrode is elevated in situ under near infrared (NIR) light irradiation, resulting in enhanced oxygen evolution activity due to its accelerated electrical conductivity, reaction kinetics, and desorption rate of O₂ bubbles from the electrode. In addition, photothermal effect can also enhance the electrocatalytic reaction rates of metal-doped Co₃ O₄ electrodes, indicating that it is able to significantly improve the OER activities of electrodes together with other modification strategies. With the assistance of the photothermal effect, the obtained Ni-doped Co₃ O₄ catalyst requires an extremely low overpotential of 208 mV to achieve a benchmark of 10 mA cm^-2 with a small Tafel slope, superior to most reported Co-based catalysts. Significantly, the electrocatalytic performance of other electrodes with photothermal effect, such as CoN, CoP, and CoS, are also boosted under NIR light irradiation, indicating opportunities for implementing photothermal enhancement in electrocatalytic water splitting.