Charge transfer of carbon nanomaterials for efficient metal-free electrocatalysis

Recently, carbon-based metal-free electrocatalysts (C-MFECs) have drawn considerable research attention because of their attractive physicochemical characteristics, cost-effectiveness, and ability to convert and store energy efficiently. Efficient intramolecular charge transfer among different parts of the carbon electrocatalyst and/or intermolecular charge transfer between electrocatalyst and electrolyte dictate the ultimate energy conversion performance. Experimental results and theoretical analyses have demonstrated that rational design of metal-free carbon nanomaterials, coupled with proper intramolecular charge transfer through heteroatom doping, incorporation of Stone-Wales defects, and/or intermolecular charge transfer through adsorption of appropriate molecules/moieties, can promote efficient electrocatalysis. In this article, we will first provide the related theoretical principles and then present an overview on the rational design and development of C-MFECs for efficient charge transfer, followed by elucidating charge-transfer processes for different electrocatalytic reactions related to renewable energy conversion and environmental remediation technologies. Finally, the current challenges and future perspectives in this exciting field will be discussed.