Chemical vapor deposition of graphene on liquid metal catalysts

Several molten metals and their alloys were used for graphene growth by atmosphere pressure chemical vapor deposition. It was found that liquid gallium (Ga) has very effective catalytic ability for graphene formation. Graphene with a controllable thickness and quality can be synthesized on a molten Ga surface only in a few minutes. Compared to solid catalysts, several new and unexpected results have been observed on Ga surface including graphene formation on a liquid surface at high temperature and keeping on a liquid surface at room temperature, time-dependent thickness control and a decrease in quality with increasing hydrogen flow. These growth characteristics can be attributed to the distinct differences in physical/chemical properties of liquid catalysts versus solids, and consequently distinct catalytic behaviors with the precursor gas. Other molten metals and alloys, including indium, tin, tin-nickle and tin-copper etc., were also explored for graphene synthesis. Use of liquid catalysts opens a new window for graphene synthesis. (C) 2012 Elsevier Ltd. All rights reserved.