Confined Nanospace Synthesis of Less Aggregated and Porous Nitrogen-Doped Graphene As Metal-Free Electrocatalysts for Oxygen Reduction Reaction in Alkaline Solution

A facile and low-emission strategy is used for preparation of porous nitrogen-doped graphene (NGR) in a confined nanospace. The negative charged graphene oxide (GO) serves as a substrate for deposition of electropositive metal amine complex and then thin layer of silica (SiO2) is formed onto the copper amine ion-coated GO. Carbonization of copper amine ion-coated GO in a confined nanospace of SiO2 and the subsequent removal of the Cu particles and SiO2 layer produces less aggregated and porous nitrogen-doped graphene (NGR). NGR materials are highly active, cheap, and selective metal-free electrocatalysts for the oxygen reduction reaction (ORR) in alkaline solution. The electron transfer for ORR at NGR catalysts is found to be around 4 at potentials ranging from -0.35 to -0.70 V. NGR may be further exploited as potentially efficient and inexpensive nonmetal ORR catalysts with good selectivity and long-term stability in alkaline solution.