posted on 2022-01-12, 16:36authored byJing He, Tianlong Zheng, Duojie Wu, Shuomeng Zhang, Meng Gu, Qinggang He
As one of the most promising non-noble
metal electrocatalysts for
the oxygen reduction reaction (ORR), previous investigations on Fe–N–C
materials have mainly focused on the innovation of synthetic methods,
identification of active sites, and structure optimization, but the
intrinsic properties of carbon supports used to anchor Fe–Nx active sites have often been neglected.
Herein, graphene oxide (GO) and reduced GO (rGO) are used as support
models for heteroatom doping to prepare Fe–N–C catalysts.
The obvious and easily distinguishable defects and the content of
oxygen-containing functional groups in GO and rGO directly determined
the doping content, structure type, and coordination environment of
N and Fe. Notably, through analysis of the surface potential as a
common parameter measured by Kelvin probe force microscopy, local
work functions of these graphene-based catalysts at the nanoscale
and their statistical averages were used to study the distribution
of active sites and their association with ORR kinetics. This insight
into the influence of carbon support structure properties on active
sites and the work function–ORR performance relationship may
provide guidance for exploring the origin of ORR activity and designing
better non-noble metal electrocatalysts.