Electron Localization and Lattice Strain Induced by Surface Lithium Doping Enable Ampere‐Level Electrosynthesis of Formate from CO₂

Abstract

The electrochemical CO 2 conversion to formate is a promising approach for reducing CO 2 level and obtaining value-added chemicals, but its partial current density is still insufficient to meet the industrial demands. Herein, we developed a surface-lithium-doped tin (s-SnLi) catalyst by controlled electrochemical lithiation. Density functional theory calculations indicated that the Li dopants introduced electron localization and lattice strains on the Sn surface, thus enhancing both activity and selectivity of the CO 2 electroreduction to formate. The s-SnLi electrocatalyst exhibited one of the best CO 2 -to-formate performances, with a partial current density of À1.0 A cm À2 for producing formate and a corresponding Faradaic efficiency of 92 %. Furthermore, Zn-CO 2 batteries equipped with the s-SnLi catalyst displayed one of the highest power densities of 1.24 mW cm À2 and an outstanding stability of > 800 cycles. Our work suggests a promising approach to incorporate electron localization and lattice strain for the catalytic sites to achieve efficient CO 2 -to-formate electrosynthesis toward potential commercialization.

Functional Aqueous Zinc–Acetylene Batteries for Electricity Generation and Electrochemical Acetylene Reduction to Ethylene

“…The as‐designed Zn–C 2 H 2 battery under a pure acetylene stream exhibits a very large open circuit potential of 1.14 V, a high power density of up to 2.2 mW cm −2 , and an energy density of 213.8 Wh kg Zn −1 , which are much higher than those for reported Zn–CO 2 batteries [18, 22–34] . Even under a crude ethylene stream containing 1 vol.…”

“…Even at a large current density of 14 mA cm −2 , the ethylene FE in the Zn–C 2 H 2 battery was still as high as 95.4 %. In contrast, current Zn–CO 2 batteries can only operate at low current densities of <10 mA cm −2 [19–34] . Furthermore, no ethane was detected, indicating that the overhydrogenation reaction of ethylene was effectively suppressed.…”

Functional Aqueous Zinc–Acetylene Batteries for Electricity Generation and Electrochemical Acetylene Reduction to Ethylene

“…The discharge polarization curve and corresponding power density of the Zn–C 2 H 2 battery under a 20 sccm pure acetylene stream are depicted in Figure 1b and S10. Significantly, a peak power density of 2.22 mW cm −2 was obtained at a current density of 12.6 mA cm −2 , which unprecedentedly exceeded those for state‐of‐the‐art Zn–CO 2 batteries such as 1.05 mW cm −2 for N atoms and coordinatively unsaturated Ni‐N 3 moieties co‐anchored carbon nanofibers (Ni‐N 3 ‐NCNFs), [30] 1.24 mW cm −2 for a surface‐lithium‐doped tin catalyst (s‐SnLi), [27] 1.36 mW cm −2 for a diatomic NiFe catalyst supported by nitrogen‐doped graphene (NiFe‐DASC), [28] and 1.8 mW cm −2 for atomically dispersed monovalent zinc anchored on nitrogenated carbon nanosheets (Zn/NC NSs) [29] . Markedly, the Zn–C 2 H 2 battery generated a stable open circuit potential of 1.14 V (Figure 1c), which was much larger than those for currently reported Zn–CO 2 batteries, for example 0.6 V for s‐SnLi, [27] 0.79 V for cedar biomass‐derived N‐doped graphitized carbon (CB‐NGC‐2), [33] and 0.82 V for carbon nanotubes directly grown on copper mesh (CNTs@Cu) [31] .…”

“…Significantly, a peak power density of 2.22 mW cm À 2 was obtained at a current density of 12.6 mA cm À 2 , which unprecedentedly exceeded those for state-of-the-art Zn-CO 2 batteries such as 1.05 mW cm À 2 for N atoms and coordinatively unsaturated Ni-N 3 moieties coanchored carbon nanofibers (Ni-N 3 -NCNFs), [30] 1.24 mW cm À 2 for a surface-lithium-doped tin catalyst (s-SnLi), [27] 1.36 mW cm À 2 for a diatomic NiFe catalyst supported by nitrogen-doped graphene (NiFe-DASC), [28] and 1.8 mW cm À 2 for atomically dispersed monovalent zinc anchored on nitrogenated carbon nanosheets (Zn/NC NSs). [29] Markedly, the Zn-C 2 H 2 battery generated a stable open circuit potential of 1.14 V (Figure 1c), which was much larger than those for currently reported Zn-CO 2 batteries, for example 0.6 V for s-SnLi, [27] 0.79 V for cedar biomassderived N-doped graphitized carbon (CB-NGC-2), [33] and 0.82 V for carbon nanotubes directly grown on copper mesh (CNTs@Cu). [31] According to the mass change of the Zn anode before and after the discharge process at 6.0 mA cm À 2 , the specific capacity of the Zn-C 2 H 2 battery was calculated to be � 786 mAh g Zn À 1 (Figure 1d), corresponding to an energy density of 213.8 Wh kg Zn .…”

Highly‐Exposed Single‐Interlayered Cu Edges Enable High‐Rate CO2‐to‐CH4 Electrosynthesis

“…[1][2][3] The production of carbon monoxide or formate by 2-electron transfer has been achieved with >90% Faradaic efficiencies (FEs) at over 1 A cm −2 partial current densities. [4,5] Methane, as the deepest C 1 reduction product with 8-electron transfer, has a high specific combustion value of 73.39 kJ mol −1 . [6] Due to the complexity of catalytic sites in heterogeneous catalysts, the CO 2 -to-CH 4 pathway needs to compete with other reduction pathways toward a variety of possible products (e.g., CO, formate, ethylene, and ethanol).…”