▎ 摘　　要

The development of efficient and stable bifunctional electrocatalysts is extremely important and challenging, especially when it comes to simultaneous electro-reduction of CO2 (ECR CO2) and electro-oxidation of organic dyes. Herein, nanorods of Co3O4 that self-assemble into Co3O4 nanospheres were anchored on nitrogen-doped reduced graphene oxide (Co3O4/N-RGO) frameworks via a hydrothermal method. Thorough physicochemical analysis revealed the small-size crystallites, the inherence of the intersheet network, and the large specific surface area of the Co3O4/N-RGO nanocomposites. X-ray photoelectron spectroscopy analysis showed that the N-doped RGO could be involved in the electronic modification of Co atoms, resulting in more Co2+ active species on the surface of the Co3O4/N-RGO nanocomposite. Electrochemical studies revealed that the Co3O4/N-RGO bifunctional electrocatalyst showed structural stability and low interface and charge transfer resistance than that of the Co3O4 catalyst. It was found that paired Co3O4/N-RGO symmetric electrodes possessed an efficient cathodic reduction of CO2 with 195 mu mol/(L cm(2)) yield of CH3OH and faradic efficiency (FE) of 74.8% and an anodic degradation of methylene blue (MB) dye at -0.7 V versus RHE (a reversible hydrogen electrode) in 1.0 M KOH alkaline solution over 60 min. A possible mechanism for bifunctional electrocatalytic reduction of CO2 and oxidation of an MB dye is schematically demonstrated. The research study highlights the potential use of Co3O4/N-RGO as a bifunctional electrocatalyst in the reduction of atmospheric hazardous wastes and the production of value-added chemicals.