Enhanced Electrochemical CO₂ Reduction to Formate on Poly(4-vinylpyridine)-Modified Copper and Gold Electrodes

Abstract

Developing active and selective catalysts that convert CO2 into valuable products remains a critical challenge for further application of the electrochemical CO2 reduction reaction (CO2RR). Catalytic tuning with organic additives/films has emerged as a promising strategy to tune CO2RR activity and selectivity. Herein, we report a facile method to significantly change CO2RR selectivity and activity of copper and gold electrodes. We found improved selectivity toward HCOOH at low overpotentials on both polycrystalline Cu and Au electrodes after chemical modification with a poly­(4-vinylpyridine) (P4VP) layer. In situ attenuated total reflection surface-enhanced infrared reflection-adsorption spectroscopy and contact angle measurements indicate that the hydrophobic nature of the P4VP layer limits mass transport of HCO3 – and H2O, whereas it has little influence on CO2 mass transport. Moreover, the early onset of HCOOH formation and the enhanced formation of HCOOH over CO suggest that P4VP modification promotes a surface hydride mechanism for HCOOH formation on both electrodes.

Facet Dopant Regulation of Cu2O Boosts Electrocatalytic CO2 Reduction to Formate

“…d) FE HCOO − of advanced Cu‐based CO 2 RR catalysts. (Cu foam, [ 22 ] P4VP‐modified Cu, [ 23 ] HOD‐CuO, [ 24 ] Cu 2 O/CuS, [ 14b ] Cu fiber felt, [ 25 ] Cu 2 O/Cu@NC‐800, [ 26 ] CuS x , [ 14a ] Cu‐Au bimetallic, [ 27 ] CuS/N,S‐rGO, [ 28 ] HCS/Cu‐0.12, [ 29 ] and this work). e) Stability test of S3‐Cu 2 O‐70 at −0.9 V RHE in 0.1 m KHCO 3 electrolyte.…”

“…The S3-Cu 2 O-70 electrocatalyst shows excellent long-term stability with more than 80 h operation at −0.9 V RHE in the H-cell, and no obvious declines in FE and current density of formate could be observed (Figure 4e). Figure 4d and Table S3 (Cu foam, [22] P4VP-modified Cu, [23] HOD-CuO, [24] Cu 2 O/CuS, [14b] Cu fiber felt, [25] Cu 2 O/Cu@NC-800, [26] CuS x , [14a] Cu-Au bimetallic, [27] CuS/N,S-rGO, [28] HCS/Cu-0.12, [29] and this work). e) Stability test of S3-Cu 2 O-70 at −0.9 V RHE in 0.1 m KHCO 3 electrolyte.…”

Porous Polymer Materials for CO2 Capture and Electrocatalytic Reduction

“…P4VP is an N-heteroaromatic polymer with a mesoporous structure that allows easy diffusion of small molecules and anions through the polymer network [ 117 , 118 ]. Nowadays, this N-polymer has been introduced into the electrochemical reduction of CO 2 reactions, and Koper and colleagues [ 119 ] showed a significant improvement in the selectivity of polycrystalline Cu and Au electrodes for HCOOH at low overpotentials after chemical modification by using poly(4-vinyl pyridine) (P4VP) layers.…”

Polymer-Regulated Electrochemical Reduction of CO2 on Ag

“…12,13,31 Spectroscopic evidence demonstrated less adsorbed CO on the P4VP-covered Cu and a higher ratio of the dissolved CO 2 relative to HCO 3 − on P4VP-covered Au, suggesting inhibited mass transport of H 2 O and HCO 3 − . 13 Aqueous mass transport effects were also supported through the modification of the hydrophilicity/hydrophobicity of the electrode interface with P4VP. Similar hydrophobicity effects were observed when alkanethiols were anchored to Cu dendrites.…”

“…In this vein, substantial research has gone toward understanding the numerous reaction pathways of the eCO 2 RR on bare metal surfaces. , While pristine electrode surfaces serve the critical role of building a foundation of understanding in the laboratory, such electrodes are not representative of those used in commercial systems. Without considering the potential complexity in the chemical makeup of CO 2 feedstocks (e.g., trace amounts of hydrocarbons), high-surface-area catalysts developed for high durability and reaction rates are typically produced by using a variety of third-party additives. ,, Of these strategies, molecules containing polar organic functional groups and even polymeric materials are a cornerstone and of late have been shown to have a critical influence over the activity and selectivity of metal catalysts for the eCO 2 RR. − …”