Graphene signatures: Identifying graphite and graphene grades via radio frequency heating

The need for reliable metrics for characterizing graphene nanosheet thickness and quality has increased, particularly as graphene production is scaled beyond kg-levels and utilized in a range of commercial applications. Here, we demonstrate a bulk, rapid testing methodology that distinguishes graphene from graphite based on our recent findings that electromagnetic fields induce rapid heating in carbon nanomaterials. For a range of graphene-family materials, we measure the heating rate as a function of frequency in response to a non-contact radio frequency field (70–130 MHz). These trends are markedly different depending on the number of layers present in the sample, with graphene products heating substantially more than parent graphite materials. Also, distinct graphene grades have a unique frequency-dependent heating response, which allows for a given graphene sample to be matched with a reference graphene grade, as confirmed by user-blind tests.