Rational design of vitamin C/defective carbon van der Waals heterostructure for enhanced activity, durability and storage stability toward oxygen reduction reaction

Metal-free defective carbon materials with abundant active sites have been widely studied as low-cost and efficient oxygen reduction reaction (ORR) electrocatalysts in metal-air batteries. However, the active sites in defective carbon are easily subjected to serious oxidation or hydroxylation during ORR or storage, leading to rapid degradation of activity. Herein, we design a van der Waals heterostructure comprised of vitamin C (VC) and defective carbon (DC) to not only boost the activity but also enhance the durability and storage stability of the DC-VC electrocatalyst. The formation of VC van der Waals between DC and VC is demonstrated to be an effective strategy to protect the defect active sites from oxidation and hydroxylation degradation, thus significantly enhancing the electrochemical durability and storage anti-aging performance. Moreover, the DC-VC van der Waals can reduce the reaction energy barrier to facilitate the ORR. These findings are also confirmed by operando Fourier transform infrared spectroscopy and density functional theory calculations. It is necessary to mention that the preparation of this DC-VC electrocatalyst can be scaled up, and the ORR performance of the largely produced electrocatalyst is demonstrated to be very consistent. Furthermore, the DC-VC-based aluminum-air batteries display very competitive power density with good performance maintenance.