Catalytic sub-surface etching of nanoscale channels in graphite

TL;DR

This paper demonstrates sub-surface etching of graphite using Ni nanoparticles, creating tunnel networks that preserve surface properties, enabling potential applications in storage and sensing.

Contribution

It introduces a novel method for sub-surface nanopore formation in graphite via catalytic Ni nanoparticles, expanding nano-patterning techniques.

Findings

Formation of tunnel networks in graphite confirmed by SEM and STM.

Top layers bend inward over tunnels without altering local density of states.

Potential for chemical modification and applications in storage or sensing.

Abstract

Catalytic hydrogenation of graphite has recently attracted renewed attention, as a route for nano-patterning of graphene and to produce graphene nano-ribbons. These reports show that metallic nanoparticles etch surface layers of graphite, or graphene anisotropically along the crystallographic zigzag <11-20> or armchair <1010> directions. On graphene the etching direction can be influenced by external magnetic fields or the substrate. Here we report the sub-surface etching of highly oriented pyrolytic graphite (HOPG) by Ni nanoparticles, to form a network of tunnels, as seen by SEM and STM. In this new nanoporous form of graphite, the top layers bend inward on top of the tunnels, while their local density of states remains fundamentally unchanged. Engineered nanoporous tunnel networks in graphite allow further chemical modification and may find applications in storage or sensing.