Oxygenation of Diamond Surfaces via Hummer’s Method

Oxygen bonded with diamond surfaces impacts important properties such as electrical conductivity, Schottky barrier height, field emission, and chemical reactivity. Though processes such as thermal, hydrogen plasma, etc., are efficient in oxidizing the hydrogen-terminated diamond surfaces, the oxidation of pristine diamond surfaces through wet chemical treatments is still in its infancy. Herein, we investigated the efficacy of Hummer’s method, one of the most celebrated chemical oxidation procedures to convert graphite to graphene oxide, to oxidize the pristine diamond surfaces. We attempted to oxidize both microcrystalline diamond powders and polycrystalline diamond wafers. Due to the presence of an acidic oxidative environment and the formation of strong oxidizing agents such as Mn₂O₇ and MnO₃⁺ during the course of the reaction, Hummer’s method is found to be very effective in oxidizing the pristine diamond surfaces. The degree of oxygen termination is validated through various spectroscopic and surface probe measurements. Microcrystalline diamond powder is more prone to oxidation to polycrystalline diamond wafers due to excess surface area, and many facets with different dangling bond densities are exposed to the oxidizing medium. The experimental observations are endorsed through molecular dynamics simulations.