perforation

Perforation by oxidation

Growing highly oriented graphite with intrinsic arbitrary curvature will be the first step in some convenient processes for patterning graphite. While continuous curved crystals of pure graphite will be useful for cookware and insulation, applications like filtration and electronics require perforated material.

At least two methods can be suggested for selectively perforating origami-like, dendritic, or other curved variants of graphite. The obvious method is to oxidize (or burn) the material, relying on the sharp bends to be more reactive than flat graphite[10]. One possible complication with this method is that oxidative etching can produce etch pits at defects within seemingly ideal graphite[11], as well as at visible kinks.

Etching or dissolving the catalytic or oxidizing particles leaves a pure, perforated graphite sample. Perforated graphite can be used for filtration or electronic devices.

If the discontinuous film is a suitable oxidation catalyst, like MoO₃, or some oxidizing species like KNO₃, heating the graphite will cause localized oxidation[1,11].

Metal or other non-volatile substance evaporated onto the sample will accumulate at sites of high curvature, when the sample is heated. This trick has been used to locate graphene edges on more conventional graphite samples[12].

The catalyst is easily removed by acid etching. Hollow semispherical shells have already been produced this way.

Initially, a typical curved graphite sample will be attached to the metal used to catalyze its synthesis. In the case of free-standing membranes, skip the next step.

Another procedure for selective oxidation of curved graphite is illustrated below: