The synergistic effect of nitrogen and fluorine co-doping in graphene quantum dot catalysts for full water splitting and supercapacitor

•N and F doped GQDs were synthesized by two-step functionalization method.•N,F-GQDs exhibit enhanced electrocatalytic and electrochemical reaction activities.•N,F co-doped GQDs efficiently work on HER, OER, and supercapacitor. Development of efficient electrochemical catalysts is crucial for clean energy technologies such as water splitting, and batteries, etc. Despite large amounts of electrocatalyst research, it remains a challenge to eco-friendly non-metal catalyst showing high performance as much as novel metal. To achieve high performance as much as noble-metal, carbon nanomaterials (CNMs) have been attracted as a candidate to the widespread application using electrochemical reaction. Herein, we report nitrogen, and fluorine co-doped graphene quantum dot (N,F-GQDs) synthesized by two-step functionalizing method for highly efficient overall water splitting. N,F-GQDs demonstrate electrocatalytic effect toward HER, and OER, and is fabricated as two-electrode full-water splitting showing good stability at various potential points. Furthermore, due to fluorine treatment, prepared N,F-GQDs exhibits enhanced electrochemical reaction property, which can induce capacitance due to the large difference of electronegativity between fluorine and carbon. N,F-GQDs is applied for the anode of super capacitance in the three-electrode system and reveal specific capacitance of 270 F g−1 at 1 mV s−1 from CV curves, and GCD capacitance of 244 F g−1 at 3 mA cm−2. This work provides a new avenue for enhancing both activities of the electrocatalytic and electrochemical reaction.