Sn-decorated Cu (Cu-Sn) electrodes were proposed as an alternative to Ag-and Au-based electrocatalysts for the selective reduction of CO 2 to CO. Here we demonstrate that selectivity does not only depend on catalyst surface composition, but is strongly affected by the electrode morphology. At current densities above 10 mA•cm -2 , we find that morphology can control the CO 2 reduction pathways to CO and other products, including the competing H 2 evolution, on the Cu-Sn surface. An electrode design with dendritic morphological features yields the highest CO partial current density of 11.5 mA•cm -2 at -1.1 V vs. RHE, avoiding the significant loss of CO selectivity observed for an electrode with less sharp, rounder morphological features. Efficient CO 2 mass transport to the catalyst surface and a high local CO 2 concentration, promoted by the dendritic structure, stabilize the Cu-SnO overlayer, suppress the competing H 2 evolution reaction, and maintain CO selectivity above 85% over a wide potential range.
A catalyst plays a key role in the electrochemical reduction of CO2 to valuable chemicals and fuels. Hence, the development of efficient and inexpensive catalysts has attracted great interest from both the academic and industrial communities. In this work, low‐cost catalysts coupling Cu and Zn are designed and prepared with a green microwave‐assisted route. The Cu to Zn ratio in the catalysts can be easily tuned by adjusting the precursor solutions. The obtained Cu–Zn catalysts are mainly composed of polycrystalline Cu particles and monocrystalline ZnO nanoparticles. The electrodes with optimized Cu–Zn catalysts show enhanced CO production rates of approximately 200 μmol h−1 cm−2 with respect to those with a monometallic Cu or ZnO catalyst under the same applied potential. At the bimetallic electrodes, ZnO‐derived active sites are selective for CO formation and highly conductive Cu favors electron transport in the catalyst layer as well as charge transfer at the electrode/electrolyte interface.
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