Insights into the electrocatalytic reduction of CO₂on metallic silver surfaces

Abstract

The electrochemical reduction of CO2 could allow for a sustainable process by which renewable energy from wind and solar are used directly in the production of fuels and chemicals. In this work we investigated the potential dependent activity and selectivity of the electrochemical reduction of CO2 on metallic silver surfaces under ambient conditions. Our results deepen our understanding of the surface chemistry and provide insight into the factors important to designing better catalysts for the reaction. The high sensitivity of our experimental methods for identifying and quantifying products of reaction allowed for the observation of six reduction products including CO and hydrogen as major products and formate, methane, methanol, and ethanol as minor products. By quantifying the potential-dependent behavior of all products, we provide insights into kinetics and mechanisms at play, in particular involving the production of hydrocarbons and alcohols on catalysts with weak CO binding energy as well as the formation of a C-C bond required to produce ethanol.

Standards and Protocols for Data Acquisition and Reporting for Studies of the Electrochemical Reduction of Carbon Dioxide

“…In contrast to Cu, Ag predominately produces H 2 and CO, with CO Faradaic efficiencies exceeding 90% at an applied potential of -1 V vs RHE. 17,18 Furthermore, the product distribution obtained over Ag is less facet-dependent than that observed over Cu. 17 To illustrate Surface preparation methods can also introduce additional variations in activity and selectivity between samples of the same metal due to the impact that these pretreatments have on 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 the purity and distribution of facets at the electrode surface.…”

CO2 Reduction: From the Electrochemical to Photochemical Approach

“…Such a dependence now is understood as Ag (110) binds COOH more strongly than other facets 69. In addition to CO and H 2 as the major products, Jaramillo and co‐workers identified four minor reduction products including formate, methane, methanol, and ethanol 71. They found that H 2 was dominant at low and high overpotentials, while CO overtook H 2 in the medium overpotential region.…”

Microstructure, surface chemistry and electrochemical response of Ag|AgCl sensors in alkaline media

“…away from the Ag substrate into the bulk solution (as schematically shown in Fig. 9c) [50]. The absorption of impurities at the surface of the AgCl layer was previously discussed in ''Surface chemistry and composition'' section.…”

“…The presence of C-based compounds is most likely related to a large extent to the (electro) chemical transformations within the process of anodization (lab air), in the sense that: enhanced surface area of the D sensor, together with the wellknown catalytic activity of Ag toward CO 2 reduction reactions, will bring about not only C-based compounds formation, but also reduction of Ag ? to metallic silver [50].…”