Hydrogen energy, as a green and environmentally friendly energy carrier, is a critical switch in energy conversion to the green economy, and the green hydrogen generation via water splitting technique from renewable energy sources is regarded as the best choice. While, the high energy input for water splitting is thermodynamically required (1.23 V), and the cell voltage can go beyond 1.8 V for the practical water electrolysis resulting from the retard kinetics of oxygen evolution reaction (OER).
