Steering surface reconstruction of copper with electrolyte additives for CO2 electroreduction

Abstract

Electrocatalytic CO2 reduction to value-added hydrocarbon products using metallic copper (Cu) catalysts is a potentially sustainable approach to facilitate carbon neutrality. However, Cu metal suffers from unavoidable and uncontrollable surface reconstruction during electrocatalysis, which can have either adverse or beneficial effects on its electrocatalytic performance. In a break from the current catalyst design path, we propose a strategy guiding the reconstruction process in a favorable direction to improve the performance. Typically, the controlled surface reconstruction is facilely realized using an electrolyte additive, ethylenediamine tetramethylenephosphonic acid, to substantially promote CO2 electroreduction to CH4 for commercial polycrystalline Cu. As a result, a stable CH4 Faradaic efficiency of 64% with a partial current density of 192 mA cm−2, thus enabling an impressive CO2-to-CH4 conversion rate of 0.25 µmol cm−2 s−1, is achieved in an alkaline flow cell. We believe our study will promote the exploration of electrochemical reconstruction and provide a promising route for the discovery of high-performance electrocatalysts.

Rational Manipulation of Intermediates on Copper for CO2 Electroreduction Toward Multicarbon Products

“…Our recent work demonstrated that ethylenediamine tetramethylenephosphonic acid (EDTMPA) molecules preferentially adsorb on Cu (110) during the CO 2 RR, inducing the selective generation of Cu (110) facets with an intrinsically high *CO binding strength (Fig. 3f, g) [39]. These studies demonstrate that the adsorption of intermediates or electrolyte additives on the catalyst surface can induce the formation of specific crystal facets with high activity; these facets are beneficial for the adsorption and conversion of intermediates.…”

“…Reproduced with permission from Ref. [39]. Copyright 2022 Springer Nature examined by thermal desorption spectroscopy.…”

“…Notably, special adsorption additives can also modulate the local proton feeding microenvironment. Our group [39] has explored boosting proton feeding toward Cu surfaces using EDTMPA additives. The adsorbed EDTMPA serves as a proton-delivering medium that accelerates the dissociation of water, providing abundant *H to assist *CO protonation toward *CHO.…”

“…To improve the selectivity and activity of C 2+ products, a variety of strategies such as grain boundary exposure [34][35][36], heteroatom doping [37,38], and local microenvironment regulation [39,40] were developed to manipulate the adsorption state of intermediates and facilitate their deep reduction.…”

Selectivity and Intrinsic Activity of Functionalized Cu Surfaces: Can the CO2 Reduction Reaction be Improved on Cu?

“…Functionalizing the Cu surface with molecular modifiers has also been attempted in vaporfed systems. 23,27,43,80,96,97 would likely be possible to take some of the functionalized catalysts from aqueous-phase experiments and incorporate them into a GDE setup, or to do a similar data analysis for already existing experimental articles with a functionalized Cu surface in a vapor-fed environment as we have here done for systems in aqueous solution, 23,27,43,80,96,97 there is a great need for benchmarking with regards to GDE systems. This is especially true in terms of intrinsic activity for a similar CO 2 RR data analysis as we have done here to be performed on GDEs.…”