Selective CO₂ Electrochemical Reduction Enabled by a Tricomponent Copolymer Modifier on a Copper Surface

Abstract

Electrochemical CO2 reduction over Cu could provide value-added multicarbon hydrocarbons and alcohols. Despite recent breakthroughs, it remains a significant challenge to design a catalytic system with high product selectivity. Here we demonstrate that a high selectivity of ethylene (55%) and C2+ products (77%) could be achieved by a highly modular tricomponent copolymer modified Cu electrode, rivaling the best performance using other modified polycrystalline Cu foil catalysts. Such a copolymer can be conveniently prepared by a ring-opening metathesis polymerization, thereby offering a new degree of freedom for tuning the selectivity. Control experiments indicate all three components are essential for the selectivity enhancement. A surface characterization showed that the incorporation of a phenylpyridinium component increased the film robustness against delamination. It was also shown that its superior performance is not due to a morphology change of the Cu underneath. Molecular dynamics (MD) simulations indicate that a combination of increased local CO2 concentration, increased porosity for gas diffusion, and the local electric field effect together contribute to the increased ethylene and C2+ product selectivity.

The application of amine-based materials for carbon capture and utilisation: an overarching view

“…phenylpyridinium in porous random copolymers can increase polymer film robustness. 223 Xie et al screened six amino acids as additives to copper nanowire catalysts. 224 Glycine led to the greatest improvement, increasing the FE of ethylene production from 9.5% to 24.0%.…”

Breaking Scaling Relationships in CO2 Reduction on Copper Alloys with Organic Additives

“… 7 , 12 − 15 Promising strategies for improving CO 2 R selectivity for C 2+ products include changing catalyst morphology 16 − 19 and electrolyte composition, 14 , 20 employing bimetallic systems and alloys, 21 − 23 and adding organic modifiers. 24 − 29 While these techniques may facilitate altered product distributions, they are not amenable to identifying empirical scaling relationships due to substantial variation in catalyst preparation and electrochemical testing conditions across independent studies. It is consequently pertinent to conduct studies that systematically and broadly vary select parameters.…”

Breaking Scaling Relationships in CO2 Reduction on Copper Alloys with Organic Additives

“…38 Also, the alloying elements substantially alter other aspects of the product distribution, making this collection of catalyst electrodes particularly well-suited for inferring intrinsic reactivity trends; the catalyst morphology is kept relatively constant with respect to the compendium of results in the literature. 9,12,14,15,[18][19][20][22][23][24]30,39 For example, through study of well-defined Cu surfaces, Hori and others identified that the relative production of CH4 and C2H4 is highly facet-dependent. 13 The distribution of exposed facets of a polycrystalline fcc-phase metal electrode could be altered via alloying due to changes in growth kinetics and/or relative surface energies upon addition of the alloying element, which would in principle provide a method to break the CH4-C2+ scaling relationship by tuning catalyst composition.…”

“…[10][11][12][13] Promising strategies for improving CO2R selectivity for C2+ products include changing catalyst morphology [14][15][16][17] and electrolyte composition, 12,18 employing bimetallic systems and alloys, [19][20][21] and adding organic modifiers. [22][23][24][25][26][27] However, identifying empirical scaling relationships from the published data is challenging due to substantial variation in catalyst preparation and electrochemical testing conditions across independent studies, highlighting the need for studies that systematically and broadly vary select parameters.…”