Field electron emission from protruded GO and rGO sheets on CuO and Cu nanorods

Abstract

Graphene and its derivatives such as graphene oxide (GO) and reduced graphene oxide (rGO) are the potential candidates for high-performance field emission devices owing to their unique geometry and electrical properties. However, flat surface of GO and rGO results in lower field emission efficiency due to emission of electrons only from sharp edges of GO and rGO sheets. In the present study, GO and rGO layers were deposited on both CuO and Cu nanorods (NRs) to enable maximum field emission current density at low applied field via geometrical field enhancement. CuO NRs were synthesized on Cu foil using wet chemical method and Cu NRs were produced through chemical and thermal reduction of CuO NRs. GO layers were deposited on CuO and Cu NRs through dip coating method. GO was converted to rGO through thermal reduction. A comparative study of the field emission properties of CuO, GO@CuO, rGO@CuO, Cu_H2, GO@Cu_H2, rGO@Cu_H2, Cu_NaBH4, GO@Cu_NaBH4, rGO@Cu_NaBH4 samples was performed. The basic idea behind deposition of GO and rGO sheets on CuO and Cu NRs was to create sharp protrusions in GO and rGO sheets to achieve enhanced field emission properties. Local field enhancement at the apex of sharp protrusions allows tunneling and hence emission of electrons from tips at considerable lower voltage. Highest current density and highest field enhancement factor were obtained in thermally reduced GO@CuO (i.e rGO@CuO) sample.