Electro-reduction of carbon dioxide at low over-potential at a metal–organic framework decorated cathode

Abstract

Electrochemical reduction of carbon dioxide is a clean and highly attractive strategy for the production of organic products. However, this is hindered severely by the high negative potential required to activate carbon dioxide. Here, we report the preparation of a copper-electrode onto which the porous metal–organic framework [Cu2(L)] [H4L = 4,4′,4″,4′′′-(1,4-phenylenebis(pyridine-4,2,6-triyl))tetrabenzoic acid] can be deposited by electro-synthesis templated by an ionic liquid. This decorated electrode shows a remarkable onset potential for reduction of carbon dioxide to formic acid at −1.45 V vs. Ag/Ag+, representing a low value for electro-reduction of carbon dioxide in an organic electrolyte. A current density of 65.8 mA·cm−2 at −1.8 V vs. Ag/Ag+ is observed with a Faradaic efficiency to formic acid of 90.5%. Electron paramagnetic resonance spectroscopy confirms that the templated electro-synthesis affords structural defects in the metal–organic framework film comprising uncoupled Cu(II) centres homogenously distributed throughout. These active sites promote catalytic performance as confirmed by computational modelling.

Au-activated N motifs in non-coherent cupric porphyrin metal organic frameworks for promoting and stabilizing ethylene production

“…Among the diverse electrocatalysts explored for CO 2 RR, metalorganic frameworks (MOFs) represent a unique category with well-defined and tunable topologic/chemical structure comprising atomically isolated active sites that not only facilitate charge transfer and mass transport, but also help furnish mechanistic understanding on the catalytic process 19,20 . However, most of the reported MOFs, in their pristine form, produce mainly C 1 products such as CO, HCOOH, and CH 4 7,21,22 . This probably arises from the distance between separated active sites in the reticular network that prohibit efficient C-C coupling, which otherwise would be more advantageous if the active sites were adjacent to each other in close proximity 23 .…”

Metal–Organic Frameworks as Heterogeneous Electrocatalysts for Water Splitting and CO2 Fixation

“…In 2020, the Schröder group developed the Cu 2 (L)-e/Cu electrode via electrochemically synthesized nano-MOF on Cu foam carrier using ionic liquid as a template (Figure a–c) . The Cu 2 (L)-e/Cu electrode (1449 m 2 g –1 ) had excellent stability and conductivity and demonstrated superior electrocatalytic activity for reducing CO 2 to HCOOH with the −1.45 V onset potential (vs Ag/Ag + ).…”

“…(a) The [Cu 2 (L)] structure; (b) Cu 2 (L)-e/Cu electrode photograph; (c) SEM images of the Cu 2 (L)-e/Cu electrode; (d) current density and time plot; (e) current density and potential plot; (f) FE HCOOH and potential plot (red: Cu 2 (L)-e/Cu, blue: HKUST-1-e/Cu and black: Cu 2 (L)-t/CP). Reproduced with permission from ref . Copyright 2020 Macmillan Publishers.…”

Tailoring the Surface and Interface Structures of Copper‐Based Catalysts for Electrochemical Reduction of CO2 to Ethylene and Ethanol

“…[22][23][24][25] For the interface structures, they mainly change the microenvironment of reaction for CO 2 RR. Typically, the organic molecules or polymers' modification on the catalyst surface can regulate the local concentration of intermediates and tune the product distribution; [26][27][28][29] the electrolyte ions can adsorb to the surface of catalyst and produce different ions effects during the CO 2 RR process. [30][31][32][33] Combined with the theoretical calculations, a variety of active sites and reaction mechanisms for CO 2 -to-ethylene/ethanol have also been proposed.…”