Ultrathin Hollow Co/N/C Spheres from Hyper‐Crosslinked Polymers by a New Universal Strategy with Boosted ORR Efficiency

Abstract

AbstractPorous carbon materials with hollow structure, on account of the extraordinary morphology, reveal fascinating prospects in lithium‐ion batteries, electrocatalysis, etc. However, collapse in ultrathin carbon spheres due to insufficient rigidity in such thin materials obstructs further enhanced capability. Based on hyper‐crosslinked polymers (HCPs) with sufficient pore structure and rigid framework, a new bottom‐up strategy is proposed to construct SiO2@HCPs directly from aromatic monomers. Heteroatom and function groups can be facilely introduced to the skeleton. The thickness of HCPs’ wall can be tuned from 9 to 20 nm, which is much thinner than that of hollow sphere synthesized by the traditional method, and the sample with a thickness of 20 nm shows the highest surface area of 1633 m2 g−1. The oxygen reduction reaction is conducted and the CoNHCS electrocatalysts with an ultrathin thickness of 5 nm display higher half‐wave potential than those of bulk samples, even better than commercial Pt/C electrode. On account of the hollow structure, the relative current density loss of electrocatalysts is only 4.1% in comparison with 27.7% in Pt/C electrode during the 15 000 s test, indicating an obvious higher long‐term stability. The new strategy to construct hollow HCPs may shed light on efficient chemical catalysis, drug delivery, and electrocatalysis.