Highly Selective Electroreduction of CO to CH on Cu-Pd Alloy Catalyst: the Role of Palladium-Adsorbed Hydrogen Species and Blocking Effect.

Electroreduction of CO to chemical fuels offers a promising strategy for controlling the global carbon balance and addressing the need for the storage of intermittent renewable energy. In this work, it is demonstrated that tuning adjacent active sites enables the selection of different reaction pathways for generating C or C products during the electroreduction of CO. Cu and Cu-Pd alloy catalysts with different atomic ratios are synthesized and investigated to elucidate their different electroreduction selectivities for CO electroreduction. Cu catalyst favors the formation of C products since the neighboring active Cu sites are beneficial for coupling adjacently adsorbed CO and CHO intermediates. Cu alloyed with Pd introduces a blocking effect and increases the intermolecular distance between adjacent adsorbed CO and CHO intermediates. Therefore the selectivity for the CH pathway decreas while the CH pathway is enhanced. Moreover, the existence of adsorbed H species on Pd atoms also played a significant role in boosting CO electroreduction to CH by facilitating the hydrogenation of CO intermediates. This work reveals the key role of H species adsorbed on Pd atoms and the blocking effect between active sites for CH formation, which is helpful for the design of copper-based catalysts for desired products.