Compositional and Geometrical Effects of Bimetallic Cu–Sn Catalysts on Selective Electrochemical CO₂ Reduction to CO

Abstract

Electrochemical reduction of carbon dioxide (CO2) is a promising method toward carbon recycling. Highly selective bimetallic catalysts have been extensively demonstrated, while efforts to understand the compositional and geometrical effects have been limited. Here, we studied the relationship between the catalytic activity of bimetallic Cu–Sn catalysts with their composition and geometry through the fabrication of three-dimensional hierarchical (3D-h) Cu nanostructure and the solution-based coating of Sn nanoparticles (NPs). As the coating time of Sn NPs was increased from 1 to 60 s, Sn NPs with a larger size and a higher surface density were coated onto the 3D-h Cu, thus the surface atomic ratio of Cu/Sn gradually decreased. This compositional change in bimetallic Cu–Sn catalysts remarkably shifted the faradaic efficiency (FE) of carbon monoxide (CO) from 90.0 to 23.4% at −0.6 VRHE. Moreover, we found that the catalytic performance increases as the geometric structure becomes complex in the order of flat, rods, and 3D-h Cu–Sn. The 3D-h Cu–Sn began to produce CO at a low potential of −0.15 VRHE and showed the maximum FECO of 98.6% at −0.45 VRHE. This study reveals that the synergetic effects of composition and nanoscale geometry are significant for the CO2 reduction reaction.

Syngas Production from Electrochemical CO2 Reduction on Copper Oxide Electrodes in Aqueous Solution

“…prepared highly selective Cu−Sn bimetallic catalysts which were capable of electrochemically reducing CO 2 to CO with a high FE CO of 98.6 % at −0.45 V vs. RHE. In addition, the electrochemical performance of the catalysts depended on the composition and nanoscale geometry effects [9] …”

Towards the Large-Scale Electrochemical Reduction of Carbon Dioxide

“…Mostly, enhancing the catalyst activity in electrochemical CO2 reduction involves tailoring the crystal morphology to better expose the active catalytic sites [66,67]. This strategy is known to provide energetically preferred sites for the adsorption of the desired CO2 reduction intermediate.…”

“…Another example of metal-stabilizing support material is that of the 3D ordered mesoporous Sn-Ti-O electrocatalysts, in, which the transfer of electron density from Ti to Sn has been shown to promote the dissociative adsorption of COOH*, thus preventing the reduction of SnOx and the removal of oxygen atoms from the crystal lattice [121]. In addition, the use of oxidized Cu nanorods as a support for the Sn catalyst has been shown to provide increased performance stability along with only a negligible change in the resulting nanostructure [66].…”

Engineering Sn‐based Catalytic Materials for Efficient Electrochemical CO2 Reduction to Formate

“…To reduce the thermodynamically stable CO 2 , catalysts are needed to increase the kinetics of the electrochemical reduction reaction and achieve an appreciable yield. Most of the catalytic materials studied to date can be divided into 1) metallic such as Au, [4–5] Ag, [6–7] Pd, [8–9] Pt, [10] Zn, [11–12] Cu, [13–15] Ni, [16–17] Fe, [18] Sn, [19–20] In, [21–22] Bi, [23] and alloys which include a combination of 2 or more of these metals, [24–33] 2) non‐metallics such as MoS 2 , [34] carbon compounds and its derivatives such as N‐doped carbon and carbon nanofibers [35–37] and 3) molecular catalysts [38–39] …”