Controlled Preparation of Silver Catalysts with Preferred Crystal Facets by Ionic Liquid-Assisted Electrodeposition for CO 2 Electroreduction

The performance of the CO 2 reduction reaction (CO 2 RR) of silver (Ag)-based catalysts is critically influenced by their crystal composition and morphology. Herein, a novel strategy for regulating the crystal composition and morphology of Ag catalysts using ionic liquids (ILs) as electrodeposition solvents was proposed. The results of structure characterization and theoretical calculations demonstrated that the unique dichloroargentate formation, induced by the IL 1-butyl-3-methylimidazolium chloride ([Bmim]Cl), could be superiorly adsorbed on the Ag(111) crystal surface. The dichloroargentate could act as a capping agent and gain electrons rapidly during electrodeposition. This phenomenon led to the formation of dendritic electrodeposited Ag composed with nanoparticles dominated by Ag(111) compared with that prepared without [Bmim]Cl. The electrocatalysts exhibited excellent CO 2 RR performance because the favorable adsorption of ILs on the surface of electrodeposited Ag increased the CO 2 concentration on the electrode surface and stabilized the CO 2 RR reaction intermediates, which achieved the highest FE CO of 99.86% and the j CO of 31.37 mA cm –2 . The maximum j CO on this Ag catalyst could reach 83.40 mA cm –2, with the FE CO exceeding 95% across a broad 0.4 V potential window. This work provided a feasible strategy for effectively tailoring the crystal composition and morphology of electrocatalysts by regulating the existence of electrodeposited precursors through ILs.