Nitrogen, Sulfur Co-doped Carbon Derived from Naphthalene-Based Covalent Organic Framework as an Efficient Catalyst for Oxygen Reduction

Developing highly efficient and low-cost electrocatalysts toward oxygen reduction reaction (ORR) is crucial for novel electrochemical energy conversion systems. In this work, we fabricated an efficient metal-free ORR catalyst with high porosity and surface area (1116 m(2) g(-1)) from a naphthalene-based covalent organic framework. The catalyst exhibits a superior ORR performance to the commercial Pt/C catalyst (with its half-wave potential 30 mV more positive) and outperforms most recently reported metal-free ORR catalysts. In addition to high ORR performance, our catalyst also demonstrates excellent methanol tolerance, outstanding stability, and high catalytic efficiency (nearly 100% four-electron path selectivity). By studying catalysts' structures and compositions, we found that the sulfur introduction can not only increase the total and ORR active N contents effectively but also grant catalysts much higher surface areas, all of which, we suggest, should be the reasonable origins for our catalyst's outstanding catalytic performance.