Cu-based N-doped/undoped graphene nanocomposites as electrocatalysts for the oxygen reduction

The development of efficient electrocatalysts for the energy-related reactions, based on earth-abundant elements, is extremely important for a sustainable energetic future. Herein, we report the application of Cu nanoparticles supported on undoped and N-doped graphene—Cu/GOE and Cu/GOE-u composites, respectively—as electrocatalysts for the oxygen reduction reaction (ORR). All the materials showed ORR electrocatalytic activities in alkaline medium. The Cu/GOE-u composite exhibited the most promising performance, with an onset potential of 0.84 V and a current density of j L = − 4.4 mA cm −2 (vs. 0.84 V and − 2.8 mA cm −2 for Cu/GOE), which revealed the great influence of the created Cu–N x /C active sites on the ORR electrocatalytic activity. The pure GOE-u support showed worse performance than the GOE, demonstrating that the N-doping advantage is not linear and also depends on the type and amount of accessible active sites created. The N-doping allowed an increase in the selectivity for the 4-electron process, resulting in a % of H 2 O 2 produced