“Charging” the cigarette butt: heteroatomic porous carbon nanosheets with edge-induced topological defects for enhanced oxygen evolution performance

Owing to the complexity of electron transfer pathways, the sluggish oxygen evolution reaction process is defined as the bottleneck for the practical application of Zn-air batteries. In this effort, metal nanoparticles (Co, Ni, Fe, etc.) encapsulated within nitrogen-doped carbon materials with abundant edge sites were synthesized by one-step pyrolysis treatment using cigarette butts as raw materials, which can drastically accelerate the overall rate of oxygen evolution reaction by facilitating the adsorption of oxygenated intermediates by the edge-induced topological defects. The prepared catalyst of nitrogen-doped carbon porous nanosheets loaded with Co nanoparticles (Co@NC-500) exhibits enhanced catalytic activity toward oxygen evolution reaction, with a low overpotential of 350 mV at the current density of 10 mA·cm⁻². Furthermore, the Zn-air battery assembled with Co@NC-500 catalyst demonstrates a desirable performance affording an open-circuit potential of 1.336 V and power density of 33.6 mW·cm⁻², indicating considerable practical application potential.