Enhancing Oxygen Reduction Electrocatalytic Activity by Constructing Carbon Dot-Cobalt (CD@Co) Composites

The oxygen reduction reaction (ORR) serves as the core cathodic reaction for fuel cells. However, the sluggish ORR kinetics and high cost of Pt-based catalysts severely restrict the commercialization of fuel cell devices. Herein, a facile in-situ synthetic strategy is developed to fabricate carbon dot-supported cobalt (CD@Co) electrocatalysts, in which carbon dots (CDs) act as both reducing agent and structural modulator. With the aim of optimizing catalytic activity and stability, the effects of CDs dosage on Co dispersion, nitrogen configuration and ORR performance are systematically investigated. The optimized CD@Co-0.12 exhibits a half-wave potential of 0.89 V (vs. RHE) and a limiting current density of 4.47 mA·cm − 2 , outperforming commercial 20% Pt/C (E 1/2 = 0.85 V). Kinetic analysis reveals a Tafel slope of 90.65 mV·dec − 1 and a near-four-electron transfer pathway ( n  ≈ 3.78). After 5000 CV cycles, only negligible potential decay is observed, demonstrating excellent stability. This work provides a low-cost and scalable strategy for designing high-performance non-precious metal ORR catalysts. Graphical Carbon dot regulated CD@Co non-precious electrocatalyst toward efficient alkaline oxygen reduction reaction