Electric Field Mediated Selectivity Switching of Electrochemical CO₂ Reduction from Formate to CO on Carbon Supported Sn

Abstract

Decades of electrochemical CO2 reduction research have led to established rules about the product selectivity, i.e., bare tin yields formic acid as the main product. Here, we present Sn nanoparticles supported on carbon nanotubes (CNTs) in a hollow fiber (Sn-CHF), which produce CO with 10 times higher selectivity than formate. Density functional theory calculations reveal that a strong interfacial field induced by the carbon support enhances the rate-limiting CO2 adsorption and thus CO production on Sn nanoparticles, whereas the field-insensitive formate and hydrogen production routes were completely suppressed and occurred mainly from carbon sites. Modification of the interfacial electric field via exchange of the electrolyte-containing cation from Li+ to Cs+ induces an unprecedented 2 orders of magnitude change in the CO current while keeping the other products almost unchanged. This work demonstrates how electrochemical selectivity rules can be modulated by controlling the interfacial field, thus opening up new windows for electrocatalyst design.

Effect of the oxidation state and morphology of SnOx-based electrocatalysts on the CO2 reduction reaction

“…Additionally, we can confirm that Sn 4+ is not the active site of the CO 2 reduction reaction. This corresponds to previously published data, for example, Lee et al [38] showed that, under neutral conditions, metallic Sn is most likely the active site of CO 2 RR. On the other hand, some authors have found that the Sn electrode possesses an oxide layer and shows excellent catalytic activity for CO 2 reduction, and that the Sn electrode removed its oxide layer, resulting in poor catalytic activity for CO 2 reduction, but with the hydrogen evolution reaction accelerating [23].…”

Nanoporous Intermetallic Cu3Sn/Cu Hybrid Electrodes as Efficient Electrocatalysts for Carbon Dioxide Reduction

“…With an aim to replace Au‐ and Ag‐based high‐cost materials, considerable research efforts have been focused on developing various electrocatalysts based on earth‐abundant elements. These include monometallic Cu atomic nanosheets [ 18 ] and pairs, [ 19 ] Sn nanoparticles, [ 20 ] Zn nanosheets, [ 21,22 ] bimetallic alloys of Cu with Al, [ 23 ] In [ 24 ] and Sn, [ 25–28 ] metal oxides, [ 29,30 ] and chalcogenides, [ 31,32 ] as well as single‐atom Mn, Fe, Co, and Ni carbonitrides [ 33–38 ] and organometallic complexes. [ 39,40 ] Nevertheless, most of them still require high overpotentials to deliver desirable current densities due to their modest activity toward the reduction of chemically inert CO 2 molecule.…”

From CO2 to Value-Added Products: A Review about Carbon-Based Materials for Electro-Chemical CO2 Conversion

“…This material with encapsulated Ni nanoparticles and abundant doped nitrogen atoms leads to a great improvement in the catalytic activity to produce CO (FE equal to 97.7% at −0.7 V vs. RHE). Lee and co-workers [203] studied the effect of the interfacial field in the CO 2 reduction reaction environment using Sn nanoparticles supported on entangled carbon nanotubes. Interfacial field modulation is a recent strategy that can have a significant impact on catalyst selectivity.…”