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

Abstract

Pd nanoparticles have been supported onto different novel carbon materials to be used in the electroreduction of CO 2 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 CO 2 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 CO 2 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-1.0 V vs Ag/AgCl. Finally, a different catalytic activity towards the CO 2 reduction reaction was observed for the different electrocatalysts, indicating an influence of the carbon support.

Electrochemical Reduction of Carbon Dioxide at Gold‐Palladium Core–Shell Nanoparticles: Product Distribution versus Shell Thickness

“…Indeed, Pérez‐Rodríguez et al. suggested that CO 2 reduction at Pd nanoparticles leads to the formation of a range of adsorbed intermediates such as HCOO ads , HCO ads and CH x species, which can be linked to the oxidation current observed in the positive‐going scan . However, these responses can be associated with H desorption processes that are shifted to more positive potentials because of surface‐adsorbed species formed previously during CO 2 reduction …”

“…Therefore, all electrochemical signals and any products formed can be attributed directly to the reduction of dissolved CO 2 . In view of the pH sensitivity of the CO 2 reduction reaction, control experiments require the solution pH to be the same in the absence and presence of CO 2 , which is often overlooked . Accordingly, the pH of Ar‐saturated Na 2 SO 4 was adjusted to pH 4 using 0.5 m H 2 SO 4 to ensure that it was the same pH as the CO 2 ‐saturated electrolyte.…”

pH effect on electrocatalytic reduction of CO2 over Pd and Pt nanoparticles

“…One challenge for CO 2 reduction is to compete with facile hydrogen evolution reaction (HER) that lowers Faradaic efficiencies toward products from CO 2 reduction [2]. Both CO 2 reduction and HER are closely associated with the adsorbed hydrogen that not only is a key intermediate for HER [3,4], but also participates in the formation of intermediates derived from adsorbed CO 2 [5][6][7][8][9]. Therefore, the reaction pathway of the adsorbed hydrogen on active sites plays important roles in activity and selectivity toward CO 2 reduction.…”

Effect of graphene with nanopores on metal clusters

“…[1][2][3][4][5] The property of metal nanoclusters is one of the major factors in determining catalytic performance. [6][7][8][9] However, the nature of support materials often has a substantial influence on the adsorption ability and catalytic activity of metal nanoclusters.…”