Non-metal doping regulation in transition metal and their compounds for electrocatalytic water splitting

Hydrogen is currently recognized as being able to mitigate the overuse of fossil fuels and as a clean energy source in future development. In addition, water electrolysis can work with renewable energy sources to make the hydrogen cycle sustainable. However, hydrogen production efficiency from water electrolysis relies on efficient catalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). At present, in order to further develop overall water splitting (OWS) catalysts, non-metal doping has attracted increasing attention. Non-metals can modulate the electronic structure, lattice structure, and surface properties of transition metal-based catalysts, which can be a new strategy to regulate the catalytic activity. Herein, the recent research progresses of non-metallic doping in transition metal-based catalysts are reviewed in this paper. This article summarizes the inherent correlation between the electronic structure and local environmental changes of water electrolysis catalytic materials with different non-metallic elements in the transition metal-based materials. Then, the reasons and related mechanisms for the improved performance of catalysts by nonmetal doping are discussed. The aim of this review is to offer some insights in favour of the role that non-metallic doping owns special advantages in electrocatalytic water splitting.