Recent Progress of Vacancy Engineering for Electrochemical Energy Conversion Related Applications

Efficient electrocatalysts are key requirements for the development of ecofriendly electrochemical energy-related technologies and devices. It is widely recognized that the introduction of vacancies is becoming an important and valid strategy to promote the electrocatalytic performances of the designed nanomaterials. In this review, the significance of vacancies (i.e., cationic vacancies, anionic vacancies, and mixed vacancies) on the improvement of electrocatalytic performances via three main functionalities, including tuning the electronic structure, regulating the active sites, and improving electrical conductivity, is systematically discussed. Recent achievements in vacancy engineering on various hotspot electrocatalytic processes are comprehensively summarized, with focus on the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), hydrogen evolution reaction (HER), nitrogen reduction reaction (NRR), CO2 reduction reaction (CO2RR), and their further applications in overall water-splitting and zinc-air battery devices. The recent development of vacancy engineering for other energy-related applications is also summarized. Finally, the challenges and prospects of vacancy engineering to regulate the electrocatalytic performances of different electrochemical reactions are discussed.