Thermally enhanced graphitic domains of graphene oxide for bifunctional single atom catalyst.

Previous studies indicate that application related properties of graphene oxide (GO) can be significantly improved by enhancing its graphitic domain size through thermal diffusion and clustering of functional groups. Here, we present the first direct observation of this size enhancement of graphitic domains from originally 200 nm2. The range of possible applications for thermally enhanced GO is extended by showing improved catalytic activity for hydrogen evolution reaction. We further examine its potential as a support for single atom (Fe) bifunctional oxygen/hydrogen evolution reaction catalyst. In this study, a highly efficient oxygen evolution reaction catalyst is synthesized by simply mixing aqueous GO solution and FeCl3, reaching overpotential values of 320 mV which is comparable to commercial benchmark IrO2. Moreover, we reveal the critical role of mass transport along GO laminates for the catalytic activity of such system.