Vertical graphene and nanodiamond composited films prepared by loading monodispersed molybdenum atoms and annealing

Abstract

Graphene/nanodiamond composited films, normally prepared by chemical vapor deposition, have attracted considerable attention due to their exceptional performance in terms of electrochemical properties, hardness and wear resistance. Here, we propose a method for preparing graphene/nanodiamond composited films by loading Mo atoms on vertical graphene sheets (VGs) and annealing them to let graphene transition to diamond under ordinary pressure. Using this method, graphene/nanodiamond composited films with different contents of diamond were prepared. It was found that after annealing at 700 °C under ordinary pressure, monodispersed Mo atoms were uniformly distributed on VGs, and a large amount of graphene transitioned to diamond, resulting in significantly reduced background current and electrochemical active area. When the annealing temperature was increased to 1100 °C, the Mo atoms agglomerated, and only a small amount of graphene transitioned to diamond, resulting in a higher content of graphene and a smaller content of diamond compared with the 700 °C annealed sample, possessing high background current and high electrochemically active area. This suggests that better dispersed Mo atoms lead to more VGs-to-diamond transition under ordinary pressure. This study provides a method for preparing graphene/nanodiamond composited films and also a way to control the content of diamond by annealing Mo-atom-loaded VGs under different temperatures.