Pd catalysts supported onto nanostructured carbon materials for CO2 valorization by electrochemical reduction

Pd nanoparticles have been supported onto different novel carbon materials to be used in the electroreduction of CO2 to high-added value products. Carbon nanocoils (CNCs), carbon nanofibers (CNFs) and ordered mesoporous carbon materials (OMCs) have been studied as support of the catalysts. In addition, Pd catalyst supported onto Vulcan XC-72R has been synthesized in order to establish a comparison with the commercial support. In this way, the influence of the carbon material on the physicochemical and electrochemical properties of the catalysts for the CO2 electroreduction process can be analyzed. Supports presented different morphologies and structures. CNFs and CNCs exhibited a crystalline structure with well-aligned graphitic layers and OMCs a hexagonal ordered structure composed of not crystalline carbon. Finally, Vulcan presented an intermediate structure between amorphous and graphitic. These differences do not affect significantly the average Pd crystallite size, although a different metal dispersion was found depending on the carbon material. On the other hand, cyclic voltammetry studies showed that CO2 was effectively reduced to other species at the surface of Pd/C catalysts. Additionally, it was proved that these species were adsorbed onto Pd at -1.0V vs Ag/AgCl. Finally, a different catalytic activity towards the CO2 reduction reaction was observed for the different electrocatalysts, indicating an influence of the carbon support. (C) 2014 Elsevier B.V. All rights reserved.