Gas-Phase Pd Clusters-Modified Mesoporous Copper Oxide Hollow Spheres As Electrocatalysts for CO2 Reduction to Ethylene

Abstract

Renewable energy-driven electrochemical CO2 conversion to value-added chemicals is a prospective strategy for addressing global carbon emission and energy consumption issues worldwide. Until today, only copper-based electrocatalysts can successfully transform CO2 into C2H4 or other desirable C2+ products, but their stability and product selectivity remain insufficient.1 Oxide-derived Cu mesoporous foam catalysts currently show the best selectivity toward C2+ product formation at particularly low overpotentials due to the availability of specific surface sites for C−C coupling in their structure and to the temporal trapping of gaseous intermediates inside the mesoporous catalyst material during CO2 electrolysis.2 To further improve their stability and product selectivity their surface can be modified with metallic clusters that can promote the adsorption of CO2 and the subsequent formation of intermediates. In particular, Pd clusters provide a favorable surface for the initial adsorption of CO2,3 while inducing a continuous restructuring of the Cu surface that maintains its catalytic properties for CO2 reduction to hydrocarbons.4 Herein, we report a novel highly efficient electrocatalyst for CO2 conversion in C2+ products based on mesoporous oxygen-rich copper hollow spheres prepared by a colloid templating method, whose surface is uniformly modified by the deposition of different loadings of well-defined Pd clusters of ca. 3 nm diameter using the laser ablation cluster beam deposition (CBD) technology.5 Primary electrochemical results show that these electrodes are able to reduce CO2 to ethylene with a faradaic efficiency of more than three times higher than that of commercial Cu2O nanoparticles under the same reaction conditions. A clear phase transition from CuO to Cu2O and metallic Cu is occurring under CO2 electro-reduction conditions as highlighted by XRD.These remarkable performances are likely originating from the facile gas charge transport via the mesoporous structure of the oxygen-rich copper spheres as imaged by SEM (Figure 1) as well as from their high surface area, which allows a high catalytic activity and a uniform accommodation of the metallic clusters.As CBD is a versatile technique that allows the deposition of virtually any type of well-defined cluster on a large variety of support, this work provides an attractive avenue to achieve stable selective multicarbon products via rational electrode design. References Kuhl KP, et al., Energy and Environmental Science, 2012;5 (5):7050-7059.Abhijit Dutta, et al., ACS Catal. 2016, 6, 3804−3814Sichao Ma, et al., J. Am. Soc. 2017, 139, 47−50Zhe Weng, et al., Angew. Int. Ed. 2017, 56, 13135 –13139Chinnabathini V. C., et al., Nanoscale, 2023, DOI: 10.1039/D2NR07287D. Figure 1