Two-Dimensional Wrinkled N-Rich Carbon Nanosheets Fabricated from Chitin via Fast Pyrolysis as Optimized Electrocatalyst
Lingfeng Gao, Daofa Ying, Tao Shen, Yiran Zheng, Jie Cai, Deli Wang, Lina Zhang
Abstract
Two-dimensional (2D) carbon nanosheets have been widely applied in many fields, and introduction of controllable N species and a wrinkled structure in 2D carbon is an appealing strategy to optimize their properties. Herein, we report a straightforward strategy for bifunctional regulation on the surface morphology (from a smooth to a wrinkled structure) and N doping of 2D carbon nanosheets by fast-pyrolyzing chitin nanosheets, which was obtained via a “top-down” exfoliation method. Our findings demonstrated that the heating rate was a key to determine the 2D wrinkled structure and type of N doping of the carbon nanosheets, and 2D wrinkled carbon nanosheets (PCNs-800-10) with hierarchical pores and enriched N species could be obtained under an optimized pyrolysis condition (ramp rate 10 °C min–1, at 800 °C for 2 h). When used as a metal-free electrocatalyst for the oxygen reduction reaction (ORR), PCNs-800-10 exhibits admirable activity, high selectivity, and excellent cycling durability of over 10 000 cycles. This was the first study to achieve the simultaneous regulation on both the wrinkled structure and the N species of 2D carbons by utilizing natural nitrogen-containing chitin without utilizing any substrates and nitrogen-containing additives, which can be extended to many other energy storage/conversion materials.