Surface/interface engineering of high-efficiency noble metal-free electrocatalysts for energy-related electrochemical reactions

To date, much efforts have been devoted to the high-efficiency noble metal-free electrocatalysts for hydrogen- and oxygen-involving energy conversion reactions, due to their abundance, low cost and multifunctionally. Surface/interface engineering is found to be effective in achieving novel physicochemical properties and synergistic effects in nanomaterials for electrocatalysis. Among various engineering strategies, heteroatom-doping has been regarded as a most promising method to improve the electrocatalytic performance via the regulation of electronic structure of catalysts, and numerous works were reported on the synthesis method and mechanism investigation of heteroatom-doping electrocatalysts, though the heteroatom-doping can only provide limited active sites. Engineering of other defects such as vacancies and edge sites and construction of heterostructure have shown to open up a potential avenue for the development of noble metal-free electrocatalysts. In addition, surface functionalization can attach various molecules onto the surface of materials to easily modify their physical or chemical properties, being as a promising complement or substitute for offering materials with catalytic properties. This paper gives the insights into the diverse strategies of surface/interface engineering of the high-efficiency noble metal-free electrocatalysts for energy-related electrochemical reactions. The significant advances are summarized. The unique advantages and mechanisms for specific applications are highlighted. The current challenges and outlook of this growing field are also discussed.