Graphene nano-cutting using biologically derived metal nanoparticles

We have developed a novel technique to cut graphene films using catalytic metal nanoparticles derived from ferritin, which is one of the proteins that contain a constant amount of Fe oxide in its inner core. For site-selective adsorption of ferritin molecules to sapphire surfaces that are partially covered with graphene films, two methods, dipping and spin-coating, were used. Graphene films were etched by the Fe-catalytic reaction with hydrogen gas at elevated temperatures. It was found that ferritin adsorption sites are controlled by graphene film edges, atomic steps of the sapphire substrate, and solution condition such as molecular concentration and ionic strength. We demonstrate that high density nanoribbons can be fabricated by using the uniformly-sized catalyst nanoparticles derived from ferritin and the aligned etching technique guided by the atomic structures of the substrate surface.