Overall Carbon‐neutral Electrochemical Reduction of CO₂ in Molten Salts using a Liquid Metal Sn Cathode

Abstract

An overall carbon-neutral CO 2 electroreduction requires enhanced conversion efficiency and intensified functionality of CO 2 -derived products to balance the carbon footprint from CO 2 electroreduction against fixed CO 2 . A liquid Sn cathode is herein introduced into electrochemical reduction of CO 2 in molten salts to fabricate core-shell SnÀ C spheres (Sn@C). An in situ generated Li 2 SnO 3 /C directs a selftemplate formation of Sn@C. Benefitting from the accelerated reaction kinetics from the liquid Sn cathode and the core-shell structure of Sn@C, a CO 2 -fixation current efficiency higher than 84 % and a high reversible lithium-storage capacity of Sn@C are achieved. The versatility of this strategy is demonstrated by other low melting point metals, such as Zn and Bi. This process integrates energy-efficient CO 2 conversion and template-free fabrication of value-added metal-carbon, achieving an overall carbon-neutral electrochemical reduction of CO 2 .Electrochemical reduction of CO 2 in aqueous solutions is limited by competitive hydrogen evolution and the low solubility of CO 2 . [1][2][3] However, it has been recently demonstrated that molten salt can function as an ideal electrolyte to capture, activate and convert CO 2 into advanced carbon and hydrocarbon. [4][5][6][7][8] This is due to a thermodynamically spontaneous reaction between CO 2 and O 2À in molten salts (Figure S1, Supporting Information), which thereby increases the solubility of CO 2 in molten salts to several moles per liter. [9][10][11][12] Molten salts also have larger electrochemical

Modulation of Excitonic Confinement of TiO2 in Molten Salts for Overall CO2 Photoreduction†

“…[ 1‐3 ] Photocatalytic CO 2 reduction is closely related to the photoinduced carrier migration kinetics. [ 4‐7 ] However, before reaching surface, most electron‐hole pairs are firmly bound through Coulombic interactions as excitons or undergo strong radiative recombination. Bulk configuration usually determines excitonic effects.…”

Pure and Metal‐confining Carbon Nanotubes through Electrochemical Reduction of Carbon Dioxide in Ca‐based Molten Salts

“…Molten salt electrolysis has a solid foundation in industrial extraction of active metals, and is recently demonstrated as a promising method to convert CO 2 into advanced energy materials for an overall carbon-neutral utilization of CO 2 . [4][5][6][7][8] Electrolytic aluminum industry as the most mature application of molten salt electrochemical metallurgy process outputs over 40 million metric tons Al in 2022 in China. [9] Using excess capacity of electrolytic aluminum industry to electrolyze industrial CO 2 emission can not only reduce carbon emission but also relieve the pressure of production regulations.…”

“…Solar‐driven electrochemical CO 2 reduction hence holds promise for artificial photosynthesis. Molten salt electrolysis has a solid foundation in industrial extraction of active metals, and is recently demonstrated as a promising method to convert CO 2 into advanced energy materials for an overall carbon‐neutral utilization of CO 2 [4–8] . Electrolytic aluminum industry as the most mature application of molten salt electrochemical metallurgy process outputs over 40 million metric tons Al in 2022 in China [9] .…”

Salt-assisted synthesis of advanced carbon-based materials for energy-related applications

“…Considering the depth of the overall synthesis strategies, the major focus is limited only to the chemical methods, including chemical vapor deposition, 17 the hydrothermal process, 18–20 pyrolysis of organic carbon precursors, 21,22 and salt-assisted synthesis. 23–26 The advantages of chemical methods over hard physical ones are demonstrated by their ease in synthesis, high reproducibility, high yields and fewer defects in carbon morphologies. Of the various chemical synthesis pathways, hydrothermal methods belong to wet-chemical processes, which require the precursors, such as glucose, to have abundant solubility in water.…”