Holey graphene denotes graphene with nanoholes in its basal plane. If the edge atoms around the holes are arranged to zigzag configuration, nonbonding π-electrons will emerge on these edge atoms and couple with itinerant π-carriers in the graphene basal planes, resulting in what have been referred to as “localized π-edge” or “Fujita” states. These states resemble those in traditional <i>3d</i> metal magnets, offering a potential explanation for some of the observed catalytic activities in the recent development of carbon-based metal-free catalysts. However, the intrinsic electrocatalytic behavior of zigzag edges in holey graphene materials has not been studied. This is because holey graphene materials fabricated by the currently-available approaches exhibit multiple types of defects concurrently, which are difficult to decouple to understand the impacts of each individual structure on the observed catalytic performance.<br/>Recently, our group developed novel approaches which enable fabrication of holey graphene materials with their basal planes nearly intact. Interestingly, the fabrication methods also beget holes with edges that are rich in zigzag geometry. The nearly pristine nature of their basal planes allows us to unambiguously study the electrocatalytic properties of zigzag edges. For the first time, it revealed that the zigzag edges are able to electrochemically catalyze oxygen reduction and the apparent electron transfer number is near to 4 in acidic conditions and around 2.5 in basic conditions. The results are in sharp contrast to the recent results with carbon materials with various defects. Careful control experiments were designed to exclude possible effects of Fe impurities originating from the starting graphite on the ORR performance. These interesting results and a molecular level understanding of these unusual and interesting results will be discussed in this presentation.

Probing the electrocatalytic behavior of zigzag edges in holey graphene nanoplatelets

256th National Meeting (2018)

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