Electrochemical Reduction of CO₂ to HCOOH over Copper Catalysts

Abstract

Although great progress has been made in the field of electrochemical CO2 reduction reaction (eCO2RR), inducing product selectivity is still difficult. We herein report that a thiocyanate ion (SCN–) switched the product selectivity of copper catalysts for eCO2RR in an H-cell. A cuprous thiocyanate-derived Cu catalyst was found to exhibit excellent HCOOH selectivity (faradaic efficiency = 70–88%) over a wide potential range (−0.66 to −0.95 V vs RHE). Furthermore, it was revealed that the formation of CO and C2H4 over commercial copper electrodes could be dramatically suppressed with the presence of SCN–, switching to HCOOH. Density functional theory calculations disclosed that SCN– made the formation of HCOO* easier than COOH* on Cu (211), facilitating the HCOOH generation. Our results provide a new insight into eCO2RR and will be helpful in the development of cheap electrocatalysts for specific utilization.

A Sulfur‐Doped Copper Catalyst with Efficient Electrocatalytic Formate Generation during the Electrochemical Carbon Dioxide Reduction Reaction

“…AEM: anion exchange membrane. Involved catalysts for comparison are including Cu/CuS x , [10c] Cu 2 O/CuS, [33] Cu/Au, [34] S‐modified Cu, [11] thiocyanate‐derived Cu, [35] S‐doped Cu 2 O, [10a] electro‐deposited CuS x , [10b] Cu 2 (CuTCPP) nanosheets, [36] HOD‐Cu, [37] Cu foam, [38] S‐derived Cu, [14] Core/Shell Cu/SnO 2 , [39] CuSn core–shell NPs, [40] Sn SAs on N‐doped graphene, [5d] SnO/C, [5c] Graphene confined Sn quantum sheets, [41] SnO 2 quantum wires, [5b] SnO 2 /Cu 6 Sn 5 /CuO, [42] Pb1Cu SAAs, [7a] Cu–Pd/Mxene, [43] BiNSs‐1, [4a] BiNSs‐2, [44] Bi 2 O 3 @C, [45] Sb SAs/NC, [46] Bi 0.1 Sn, [47] Cu‐Spy, [13] Cu hollow fiber@CNT‐Bi, [48] Sn 0.8 Bi 0.2 @Bi‐SnO x , [49] Cu 2 SnS 3 [50] . For (e, f), brown labels: Cu‐involved catalysts, light green labels: Sn‐ involved catalysts, purple labels: Bi‐ involved catalysts, dark grey label: Pb‐ involved catalyst, black label: Pd‐involved catalyst, and olive label: antimony (Sb)‐involved catalyst.…”

Ligand-Controlled Electroreduction of CO2 to Formate over Facet-Defined Bimetallic Sulfide Nanoplates

“…However, moderate FE HCOO – values ranging from 30.0 ± 8.0% to 62.4 ± 3.4% at −1.2 V RHE were obtained under the same testing conditions (Figures e and S12). These results demonstrate that distinct from other capping ligands, thiocyanate not only activates Cu 2 SnS 3 nanoplates for efficient CO 2 R by displacing OLAM, but also imparts superior formate selectivity likely attributable to electronic effects (see below) …”

“…These results demonstrate that distinct from other capping ligands, thiocyanate not only activates Cu 2 SnS 3 nanoplates for efficient CO 2 R by displacing OLAM, but also imparts superior formate selectivity likely attributable to electronic effects (see below). 42 The dynamic evolution of catalyst microstructures can dictate CO 2 R activity and selectivity. Previous studies have shown that with copper sulfide-and tin sulfide-based CO 2 R catalysts, metallic Cu or Sn domains and new material interfaces could form during electrolysis and serve as the active sites.…”

A topological chemical transition strategy of bismuth-based materials for high-efficiency electrocatalytic carbon dioxide conversion to formate

“…[4][5][6] Over the past few years, the two-electron product of formate has proven to be a promising energy commodity for various industrial processes, presenting high values in economic and practical application beneting from high energy density and safe storage. [7][8][9][10] The key is exploring robust and highly active catalysts to accelerate the conversion from the key *OCHO intermediate to formate and inhibit the competition for side reactions.…”