Highly Selective and Active Pd-In/three-dimensional Graphene with Special Structure for Electroreduction CO2 to Formate

Electrocatalytic reduction of CO2 to formate on carbon based electrodes is known to suffer from low electrochemical reaction activity and product selectivity. Pd/three-dimensional graphene (Pd/3D-RGO), In/3D-RGO and Pd-In/3D-RGO for the electrochemical reduction of CO2 were prepared by a mild method that combines chemical and hydrothermal. The metal/3D-graphenes (metal/3D-RGO) were characterized by scanning electron microscopy, X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy (XPS). Cyclic voltammetry and the ion chromatography were performed to investigate the electrochemical performance of the metal/3D-RGO. The morphology and dispersion of metal/3D-RGO are 3D structure with amount of interconnected pores with metal NPs loading on the fold. And the Pd-0.5-In-0.5/3D-RGO show excellent surface performance with well dispersion and smallest particle size (12.8nm). XPS reveal that binding energy of Pd (In) NPs is shifted to negative energy, for the metal lose electrons in metal and combine with C, which is demonstrated in the HNO3 experiment. The peak potential of Pd-0.5-In-0.5/3D-RGO is -0.70V (vs. Ag/AgCl), which is more positive than In-1.0/3D-RGO (-0.73V) and Pd-1.0/3D-RGO (-1.2V). The highest faradaic efficiency (85.3%) happens in Pd-0.5-In-0.5/3D-RGO at -1.6V vs. Ag/AgCl. In these experiments, the special structure that metal NPs combine with C and the bimetal NPs give a direction to convert CO2 to formate.