Gentle Graphene Oxidation Via Atomic Oxygen

Graphene’s exceptional popularity stems from the expectation that the material’s properties will lead to applications in electronics and other areas. But those applications typically require mating graphene chemically with other materials to build functional devices. Unfortunately, graphene’s inertness can thwart efforts to fabricate such devices. Researchers commonly deal with the inertness via harsh acidic oxidation, which endows the material with oxygen-containing functional groups. In subsequent steps, scientists typically reduce oxidized graphene chemically or thermally to restore its native properties. But the reduction is incomplete, and the process leaves graphene with defects and undesirable properties. A team led by Northwestern University’s James E. Johns and Mark C. Hersam reports that those problems can be avoided by oxidizing instead with atomic oxygen, which they prepare by splitting O₂ thermally (J. Am. Chem. Soc. 2013, DOI: 10.1021/ja408248z). In a proof-of-concept test, the team alternately exposed graphene to oxygen atoms and diethylzinc, which formed a stable, uniform coating of zinc oxide nanoclusters. Metal oxide-coated graphene is used in electronics and photocatalysis. Surface analyses show that the method leaves graphene’s morphology intact and defect-free, the team reports.