Hierarchically 3D Porous Ag Nanostructures Derived from Silver Benzenethiolate Nanoboxes: Enabling CO₂ Reduction with a Near-Unity Selectivity and Mass-Specific Current Density over 500 A/g

Abstract

Silver nanostructures with hierarchical porosities of multiple length scales have been synthesized through electrochemical reduction of silver benzenethiolate nanoboxes. The porous Ag nanostructures exhibit superior catalytic performance toward electrochemical reduction of CO 2 . The Faradaic efficiency of reducing CO 2 to CO can be close to 100% at high cathodic potentials, benefiting from the readsorbed benzenethiolate ions on the Ag surface that can suppress the hydrogen evolution reaction (HER). Density functional theory calculations using the SCAN functional reveal that the disfavored H binding on the benzenethiolate-modified Ag surface is responsible for inhibiting the HER. The mass-specific activity of CO 2 reduction can be over 500 A/g because the multiple-scale porosities maximize the diffusion of reactive species to and away from the Ag surface. The unique multiscale porosities and surface modification of the as-synthesized Ag nanostructures make them a class of promising catalysts for electrochemical reduction of CO 2 in protic electrolytes to achieve maximum activity and selectivity.

In situ construction of thiol-silver interface for selectively electrocatalytic CO2 reduction

“…1(a)). Nanostructured Ag supported by porous carbon could be intentionally obtained with significantly increased specific surface area and thiol-mediated active sites for high intrinsic ECR activity, confinement effect on the reaction intermediates for high selectivity, as well as strong interaction between the thiol molecules and silver with a result of high stability [23,[35][36][37][38][39][40][41]. Compared with common Ag NPs without Ag-thiol motifs, it has higher CO 2 conversion activity and the highest Faradaic efficiency (FE) of 86.7% at −1.0 V versus reversible hydrgen electrode (RHE).…”

Surface Oxidized Ag Nanofilms Towards Highly Effective CO2 Reduction

“…Lots of efforts have been concentrated on Ag‐based electrocatalysts, aiming at higher CO selectivities at lower overpotentials. Various Ag nanomaterials with high specific surface areas, such as nanoparticles, [26,27] nanosheets, [28] nanowire [25] and porous Ag [29,30] have been reported, which offer mass‐transport advantages in CO 2 reduction. In addition, more efforts were devoted to improving the intrinsic activity of Ag sites for CO 2 reduction, for example, by engineering more low‐coordinated sites [25,26] and active crystal planes [31] .…”

Ag Nanowires/C as a Selective and Efficient Catalyst for CO2 Electroreduction

“…Three-dimensional porous Ag, or Ag foam electrodes, present remarkable Faradic efficiencies of CO, over 90% [30,31]. However, a large quantity of Ag is required to achieve high catalytic activity on these macroscopic Ag bulk electrodes, which is the inherent defect of Ag bulk materials.…”