Rational Design of Silver Sulfide Nanowires for Efficient CO2 Electroreduction in Ionic Liquid

Electroreduction of CO 2 holds the promise for the utilization of CO 2 and the storage of intermittent renewable energy. The development of efficient catalysts for effectively converting CO 2 to fuels has never been more imperative. Herein, we successfully synthesized Ag 2 S nanowires (NWs) dominating at the facet of (121) using a modified facile one-step method and utilized them as a catalyst for electrochemical CO 2 reduction reaction (CO 2 RR). Ag 2 S NWs in ionic liquid (IL) possess a partial current density of 12.37 mA cm –2, ∼14- and ∼17.5-fold higher than those of Ag 2 S NWs and bulk Ag in KHCO 3, respectively. Moreover, it shows significantly higher selectivity with a value of 92.0% at the overpotential (η) of −0.754 V. More importantly, the CO formation begins at a low η of 54 mV. The good performance originates from not only the presence of [EMIM–CO 2 ] + complexes but also the specific facet contribution. The partial density of states (PDOS) and work functions reveal that the d band center of the surface Ag atom of Ag 2 S(121) is closer to the Fermi energy level and has a higher d-electron density than those of Ag(111) and Ag55, which lowers transition state energy for CO 2 RR. Besides, density functional theory (DFT) calculations indicate that the COOH* formation over Ag 2 S is energetically more favorable on (111) and (121) facets than that on Ag(111) and Ag55. Therefore, we conclude that the significantly enhanced performance of Ag 2 S NWs in IL synergistically originates from the solvent-assisted and specific facet-promoted contributions. This distinguishes Ag 2 S NWs in IL as an attractive and selective platform for CO 2 RR.