Ultra-small Co/CoO_(x) nanoparticles dispersed on N-doped carbon nanosheets for highly efficient electrocatalytic oxygen evolution reaction

摘要

In this paper,we report a facile strategy to synthesize Co-BDC-NH2 material,which is used as a precursor towards an excellent OER electrocatalyst by thermal annealing in nitrogen.Ultra-small Co/Co Oxnanoparticles were uniformly dispersed on the rhombus N-doped carbon(NC)nanoflakes.Transmission electron microscopic,X-ray diffraction spectrometric,and X-ray photoelectron spectroscopic analyses revealed the coexistence of metallic Co and Co oxides nanoparticles.It was found that Co/CoO_(x)@NC obtained at 500°C annealing temperature exhibited the highest electrocatalytic OER activity,with 307 and375 m V overpotential to achieve 10 and 100 m A cm^(-2) current densities.Besides,thanks to the in-situ annealing process,Co/CoO_(x)@NC showed excellent catalytic stability with 97.4%current density retention after 24 h electrolysis at 1.66 V vs.RHE electrode potential.Further investigations revealed that the ultrasmall Co/Co Oxnanoparticles distributed on N-doped carbon template contribute significantly towards OER electrocatalysis through enlarging the activity surface areas and enhancing the intrinsic electrochemical activity due to the presence of metallic Co.