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

Abstract

The electrocatalytic reduction of CO2 at carbon-supported Au-Pd core-shell nanoparticles is systematically investigated as a function of Pd shell thickness. Liquid and gas phase products were determined by off-line 1 H NMR and on-line electrochemical mass spectrometry (OLEMS). Our results uncover the relationship between the nature of products generated and the Pd shell thickness. CO and H2 are the only products generated at 1 nm thick shells, while shells of 5 and 10 nm produced HCOO -, CH4 and C2H6. The concentration of HCOO -detected in the electrolyte was dependent on the applied potential, reaching a maximum Faradaic efficiency of 27% at -0.5 V vs. RHE for 10 nm thick shells. We conclude that collisions between absorbed hydrogen at relaxed Pd lattices and strongly bound "COlike" intermediates promote the complete hydrogenation to C1 and C2 alkanes, without the generation of other products such as alcohols and aldehydes.

Free Standing Nanoporous Palladium Alloys as CO Poisoning Tolerant Electrocatalysts for the Electrochemical Reduction of CO2 to Formate

“…An expansive leap in both the distribution of products and product selectivity for the CO2RR occurred with the transition from bulk polycrystalline metals 9 to nanostructured materials 15,37,44,[60][61][62][63] . This is especially true for Pd.…”

“…The 2-electron CO2RR to HCOO -(near neutral bicarbonate electrolytes), with a reversible potential of approximately 0.02 V vs. RHE 39 has been termed an electrohydrogenation process where the simultaneous transfer of a proton and electron forms an 4 adsorbed HCOOad intermediate rather than COad 37 . The source of the high electrohydrogenation activity of Pd has been suggested to be due to its ability to form a saturated hydride phase near 0 V vs. RHE [40][41][42] , H/Pd ratios as high as 0.7 43 . The difference in observed FE and selectivity for HCOOwhen comparing planar, polycrystalline electrodes to nanostructured materials is likely related to the rate of formation and degree/ease of participation of the α,β-PdH active phase, which is likely more facile on nanostructured surfaces with a higher defect density 37,41,44,45 .…”

Facile Deposition of Cu−SnOx Hybrid Nanostructures on Lightly Boron‐Doped Diamond Electrodes for CO2 Reduction

“…Such change in lattice direction in a Cu/SnO 2 core/shell nanostructure was suggested for superior and selective CO 2 reduction. Similarly; activity and product selectivity in electrochemical CO 2 reduction are reported to be dependent on the thickness of Cu and Pd shells in the Au/Cu and Au/Pd core/shell nanostructures, respectively ,. In addition to alloy and core/shell catalysts which show cooperative effects to reduce CO 2 selectively, surface oxides of the catalysts also play crucial role in CO 2 reduction reaction ,.…”

“…Similarly thin SnO 2 coatings on the Cu and Ag 3 Sn core/shell nanoparticles showed selective electrochemical production of CO and HCOOH, respectively ,. Activities of other core/shells and alloys materials are also reported to be higher towards electrochemical CO 2 reduction . Probable reasons of these alloys and core‐shells catalysts for higher selectivity and activity in electrochemical CO 2 reduction have been carried out by the research community.…”

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

“…In order to solve these problems, bimetallic have received attention for excellent electrocatalytic capabilities compared to monometal . Though bimetallic Pd‐based nanoparticles such as Pd−Au , Pd−Cu show pretty catalytic activity, the problem of selectivity and CO poisoning is still presence. Among various metals researched, Indium has been chosen for its excellent catalytic performance and ability of electrochemical CO 2 conversion to formate at comparatively low overpotential .…”