Pre-leaching strategy for tuning porosity and composition to generate Co2P/Co@P/N-doped carbon towards highly efficient bifunctional oxygen electrocatalysis

Abstract

Constructing porous nonprecious metal heteroatom-doped carbon catalysts with efficient and robust electrocatalytic properties for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is identified as a pivotal part for propelling practical application of diverse energy-related devices. This study reports a facile and eco-friendly method to synthesize micro-/mesoporous Co2P/Co-embedded P/N co-doped carbon (Co/P/N–CNP) material through H3PO4-selective-etching ZIF-67 precursor and subsequent pyrolysis. H3PO4 not only acts as an etching agent to engineer ZIF’s porosity but also is an ideal phosphorus source for P-doping in carbon matrix and the formation of Co2P, which greatly enriches the electrocatalytic active sites for obtained carbon catalysts. Pyrolyzed hybrid carbon nanomaterial (Co/P/N–CNP) is decorated by multiwalled carbon nanotubes and possesses micro- and mesopores simultaneously, which facilitate the exposure for more active sites and the diffusion of reactive species in the ORR/OER electrocatalytic process. Thanks to the promising physicochemical characteristics, finely-tuned Co/P/N–CNP catalyst manifests excellent bifunctional electrocatalytic activity compared with commercial Pt/C (for ORR) and RuO2 (for OER) in alkaline media. This simple strategy paves a new avenue for its further application in catalyst fabrication for energy storage and conversion.