Multilayer meso–microporous carbon nanomesh: an effective oxygen reduction electrocatalyst

Abstract

The exploration and development of electrocatalysts with high utilization of active sites toward the oxygen reduction reaction (ORR) is crucial for zinc–air batteries. Nitrogen-doped carbon catalysts have emerged as attractive candidates. However, they suffer from low utilization of active sites since the bulk carbon matrix exhibits numerous mass transfer ‘dead zones’. Herein, a thermal exfoliation and etching strategy is employed to synthesize an accordion-like N-doped carbon nanomesh (A-NC-M) using a novel multilayer two-dimensional (2D) zeolitic imidazolate framework (ZIF) as the precursor rather than a conventional bulk three-dimensional (3D) ZIF. The as-prepared A-NC-M inherits the multilayer 2D shape of the ZIF precursor and has a unique hierarchically interconnected nanomesh structure with many mesopores and micropores. Taking advantage of the high utilization of active sites, large surface areas (1512.3 m² g⁻¹), and fast mass/electron transport of the 2D layered structure, A-NC-M as an ORR electrocatalyst displays a half-wave potential of 0.899 V in 0.1 M KOH, surpassing the benchmark Pt/C by 42 mV. The zinc–air battery assembled by the A-NC-M catalyst delivers a higher power density and specific capacity than those of Pt/C. This study provides insight into the rational construction of novel carbon nanostructures for extended electrocatalytic and energy applications.