Superstructured Carbon with Enhanced Kinetics for Zinc-Air Battery and Self-Powered Overall Water Splitting.

Abstract

The present study proposes a novel engineering concept for the customization of functionality and construction of superstructure to fabricate 2D monolayered N-doped carbon superstructure electrocatalysts decorated with Co single atoms or Co2 P nanoparticles derived from 2D bimetallic ZnCo-ZIF superstructure precursors. The hierarchically porous carbon superstructure maximizes the exposure of accessible active sites, enhances electron/mass transport efficiency, and accelerates reaction kinetics simultaneously. Consequently, the Co single atoms embedded N-doped carbon superstructure (Co-NCS) exhibits remarkable catalytic activity toward oxygen reduction reaction, achieving a half-wave potential of 0.886V versus RHE. Additionally, the Co2 P nanoparticles embedded N-doped carbon superstructure (Co2 P-NCS) demonstrates high activity for both oxygen evolution reaction and hydrogen evolution reaction, delivering low overpotentials of 292mV at 10mAcm-2 and 193mV at 10mAcm-2 respectively. Impressively, when employed in an assembled rechargeable Zn-air battery, the as-prepared 2D carbon superstructure electrocatalysts exhibit exceptional performance with a peak power density of 219mWcm-2 and a minimal charge/discharge voltage gap of only 1.16V at 100mAcm-2 . Moreover, the cell voltage required to drive an overall water-splitting electrolyzer at a current density of 10mAcm-2 is merely 1.69V using these catalysts as electrodes.