ABSTRACT
Along with the intensified global energy crisis and climate change, it is particularly crucial to accelerate the transformation of the energy structure and gradually increase the percentage of new energy. Currently, electrochemical water splitting is widely regarded as one of the most promising hydrogen production technologies, with considerable implications for tackling the challenge of global warming and achieving the goal of “carbon neutrality”. The oxygen evolution reaction (OER) is a crucial anode reaction for water splitting, metal-air batteries, and renewable fuel cells. However, the OER process contains four proton–electron transfer steps, resulting in a slow kinetics, which has long been the bottleneck. In general, noble metals and their oxides (RuO2 and IrO2) are considered to be promising catalysts for OER, but the high price and scarce resources restrict their wide-scale application. Hence, it is crucial to develop low-cost, high-activity and stable catalysts for improving the efficiency of water splitting. Recently, significant attention has been dedicated to non-noble transition metal materials as promising alternatives for water splitting. Gaining a comprehensive understanding of the intrinsic catalytic mechanism and identifying the active sites of catalysts will greatly benefit the rational design and effective application of high-efficiency catalysts.
