Advances in understanding the regulation effect of carbon dots on intrinsic activity of metal and metal-free catalysts for electrocatalysis reaction

•Application of CDs to regulate intrinsic structure of metal or metal-free materials.•The structure–activity relationship towards CDs-based composite is revealed.•Opportunities and challenges for application of CDs-based materials are discussed. Electrochemical energy conversion and storage devices support a promising green, efficient renewable way to solve energy-supply shortages and environmental problems. To promote reaction rates of involved electrochemical reactions, non-metal or noble metal electrocatalysts are elaborately designed. For optimizing the intrinsic structure and decreasing the cost, functional carbon dots (CDs) are chosen to add into these metal or metal-free materials, benefitting from their unique advantages of abundant surface functional groups, excellent electron acceptor/donor properties and high specific surface area. This review aims to support a summary of recent breakthrough in the application of CDs to regulate intrinsic structure of metal or metal-free materials including dispersibility, utilization efficiency, electronic state, partial charge distribution, and coordination environment of active atom-sites. Moreover, electrocatalytic performances (including stability, conductivity and antitoxicity, etc.) are also systematically investigated. Except that, the potential opportunities and challenges for application of CDs-based materials in the future are also discussed to promote the development of this field.