Ag Displacement on Cu Foam with Additives for Electrochemical Reduction of Carbon Dioxide to Carbon Monoxide

Abstract

For electrochemical reduction of carbon dioxide to carbon monoxide, an Ag catalyst supported by Cu foam was prepared electrochemically by bubble-templated Cu electrodeposition and subsequent Ag galvanic displacement. The morphology and crystal structure of the displaced Ag on the Cu foam varied significantly depending on the type of additive. Electrochemical analysis revealed variations in the electrochemical surface area and different Ag and Cu surface compositions depending on the type of additive used in the Ag galvanic displacement step. Among the prepared Ag/Cu foams, the foam having the highest Ag(220)/Ag(111) ratio exhibited the highest CO Faradaic efficiency at a certain constant potential. In the potential range between −0.46 and −0.96 V RHE , the Ag(220)/Ag(111) ratio significantly affected the normalized CO partial current, showing the importance of control of a certain facet in the Ag crystal structure by the additives.

Electrodeposited AgCu Foam Catalysts for Enhanced Reduction of CO2 to CO

“…Interestingly, AgCu catalysts exhibit similar selectivities as the pure Ag foam catalyst. When comparing the recent reports on AgCu systems with our study, the studied catalysts exhibit a significant improvement in CO selectivity especially at lower overpotentials (−0.4 to −0.7 V vs RHE). ,,, …”

“…When comparing the recent reports on AgCu systems with our study, the studied catalysts exhibit a significant improvement in CO selectivity especially at lower overpotentials (−0.4 to −0.7 V vs RHE). 27,30,31,41 To better understand this interesting behavior of AgCu catalysts toward CO formation, CO partial current densities are calculated from the amount of CO detected at the potential of interest and their respective steady state current from chronoamperometry. Figure 7a shows the CO current densities plotted as a function of the overpotentials, assuming a thermodynamic reduction potential of −0.11 V vs RHE for CO 2 to CO. 22 All the electrodeposited catalysts exhibit enhanced catalytic current density compared to bulk Ag foil.…”

“…Chang et al prepared bimetallic AgCu by galvanostatically displacing Cu with Ag from an electrodeposited Cu and reported a volcano-like curve for the faradaic efficiency of C 2 products with a maximum of 14% at −0.75 V vs RHE. However, many other researchers including us were able to report higher values on similar Cu structures without Ag. , AgCu foams prepared by Lee et al using a similar synthetic route via galvanostatically displacing electrodeposited Cu with Ag showed the highest faradaic efficiency of 17.8% for CO at −0.66 V vs RHE in 0.1 M KHCO 3 solution . The CO FEs are proposed to be proportional to the Ag(220)/Ag(111) ratio, which is controlled using various additives.…”

“…28,29 AgCu foams prepared by Lee et al using a similar synthetic route via galvanostatically displacing electrodeposited Cu with Ag showed the highest faradaic efficiency of 17.8% for CO at −0.66 V vs RHE in 0.1 M KHCO 3 solution. 30 The CO FEs are proposed to be proportional to the Ag(220)/Ag(111) ratio, which is controlled using various additives. When Cu is electro-deposited together with Ag, the electrodeposited Ag 57 Cu 43 outperformed the electrodeposited Ag under similar conditions by more than 2 times in terms of mass activity at −0.83 V vs RHE.…”

Facile and large‐scale production of Ag nanoparticles for selective electrochemical CO2 reduction reaction

“…While metals such as Au, Ag, Zn, Pd, and Ga are good candidates, 6 both Au and Ag are more efficient electrocatalysts for CO production than the other metals. Ag is more suitable than Au for large scale applications because of its low cost 7 …”