Synthesis of graphene-quantum-dots decorated metal-free carbon nitride for effective electrocatalysts in redox-mediated electrolyte

Defect engineering of N/C 3 N 4 two-dimensional material provides an efficient way to tune the electronic structures and make more active sites for electrocatalysis, which is attractive for electrochemical energy storage applications. Other than modification of heteroatoms on the top of C 3 N 4 two-dimensional material as a photosensitizer, electrolyte design is very desirable to enrich the research area and provides a wide range of choices for diverse applications. Herein, the graphene quantum dots (GQDs) decorated N doped g-C 3 N 4 electrocatalysts for water splitting were fabricated, which exhibited enhanced electron transfer efficiency, better electrocatalytic performance, and long-term stability. The electrochemical performances of GQDs@C 3 N 4+ x in neutral, acidic, alkaline, and redox-mediated electrolytes were investigated, respectively. The GQDs@C 3 N 4+ x electrode displays excellent activity toward electrocatalytic reaction in redox-mediated solution. The increase in electrocatalytic performance could be attributed to the reaction of redox species with the surface holes and the defects of GQDs@C 3 N 4+ x , leading to a better separation of the excited electron-hole pairs. Thus, this work greatly broadens the application prospects of carbon nitrogen complex by rational defect engineering and electrolyte regulation.