Facile Synthesis of Sub‐Nanometric Copper Clusters by Double Confinement Enables Selective Reduction of Carbon Dioxide to Methane

Abstract

Previous density-functional theory (DFT) calculations show that sub-nanometric Cu clusters (i.e., 13 atoms) favorably generate CH 4 from the CO 2 reduction reaction (CO 2 RR), but experimental evidence is lacking. Herein, a facile impregnation-calcination route towards Cu clusters, having a diameter of about 1.0 nm with about 10 atoms, was developed by double confinement of carbon defects and micropores. These Cu clusters enable high selectivity for the CO 2 RR with a maximum Faraday efficiency of 81.7 % for CH 4. Calculations and experimental results show that the Cu clusters enhance the adsorption of *H and *CO intermediates, thus promoting generation of CH 4 rather than H 2 and CO. The strong interactions between the Cu clusters and defective carbon optimize the electronic structure of the Cu clusters for selectivity and stability towards generation of CH 4. Provided here is the first experimental evidence that sub-nanometric Cu clusters facilitate the production of CH 4 from the CO 2 RR.

Promoting CO2 methanation via ligand-stabilized metal oxide clusters as hydrogen-donating motifs

“…3b ) and CO 2 -to-CH 4 conversion rate of 0.17 μmol cm −2 s −1 of CoO-2.5 nm/Cu/PTFE, which improve by a factor of 2.6x relative to the best previous reports having a CH 4 FE higher than 50% (Supplementary Table 2 ). The catalyst system reported herein achieved a half-cell energy efficiency of 27% in neutral medium (Supplementary Note 1 ), which is among the best previously reported catalysts with current densities above 50 mA cm −2 (Supplementary Table 2 ) 13 – 20 .…”

“…Red circle for methane, blue circle for hydrogen and grey circle for C 2 products. b CO 2 -to-CH 4 performance of CoO/Cu/PTFE in comparison with recent reports 13 – 20 . Blue square for the results in literature.…”

“…This motivates the need for practical electrolyzers which convert CO 2 to CH 4 at high rates and energy efficiency 9,10 . Along the way to this goal, further progress is required in the electrocatalysts which facilitate the conversion chemistry [11][12][13][14][15][16][17][18][19][20] . By judicious adjustment of CO 2 partial pressure, copper (Cu) catalysts have attained a 48% faradaic efficiency (FE) to CH 4 (ref.…”

Recent Advances in Strategies for Improving the Performance of CO2 Reduction Reaction on Single Atom Catalysts

“…Based on the previous diatomic strategy in a two‐step tandem reaction for producing CH 4 , multi atomic catalyst for ECR might be in favor of the design of C 2 and C 3 products. ii) Tandem catalysts comprised of SACs and Cu‐based catalyst, might be another candidate to produce C 2 and C 3 [46f,103] . The formation of CC in Cu‐based catalyst are easier than other catalysts and SACs play a part in improving efficiencies and activities of C 2 and C 3 .…”

“…The uniqueness of Cu SACs in respect to selecting support is similar to that only Cu‐based metals and metallic compound can produce C 2 and C 2+ . [ 46 ] Wang et al proposed a feasible method to prepare copper‐doped, mesoporous CeO 2 nanorods for ECR to CH 4 . [ 27 ] The localized evironment modulation on CeO 2 is realized by Cu substitution, where the Cu atoms occupy the holes of Ce atoms on CeO 2 surface, and thus promote the FE CH4 .…”