Electrochemical deposition of carbon nanotubes from CO₂in CaCl₂–NaCl-based melts

Abstract

As part of the efforts to address global climate change, the identification of methods for the capture of carbon dioxide and its selective electrochemical conversion into value-added carbonaceous materials in molten salt electrolytes is a research topic of scientific and technological significance.

Capture and electro-splitting of CO2 in molten salts

“…In the view of continuous operation, the electrochemical reduction rate should be well matched with that of CO 2 capture, achieving a net transformation of CO 2 . The electrochemical reduction rate can be easily tuned by adjusting the electrode potential and current density [2,22,29] . Therefore, the net CO 2 transformation rate was mainly determined by the CO 2 absorption process.…”

“…This indicated that the molten salt composition and the absorbents have a significant influence on the CO 2 capture rate. Other conditions such as temperature, agitation and the molten salt depth can also affect the initial CO 2 absorption rate [2,17,22,26,29,32] .…”

“…Furthermore, catalysts with complex structures are needed for CO 2 conversion in aqueous solutions [20] . Although the CO 2 solubility in RTILs is higher, the high cost of RTILs as well as slow reaction kinetics prevents them from widespread adoption in commercial applications [18,22] . Compared with the aqueous solution and RTILs, the low-cost inorganic molten salts have many advantages.…”

Optimized Electrolytic Carbon and Electrolyte Systems for Electrochemical Capacitors

“…The influence of deposition temperature, [23][24][25][29][30][31] substrate, [23,29,30,[32][33][34][35] electrolyte, [29,30,36] current density, [30,37] and potential [4,24,25,32,33,31,35,38] have all been investigated, with a rich and varied library of carbon microstructures being produced, and with links being drawn between the structure of these carbons and the conditions of electrodeposition. In more recent years this understanding of the molten carbonate system has paved the way for an increased understanding of both the mechanism of carbon formation from molten carbonate salts, [39][40][41] and for the application of molten carbonate reduction in attempts to produce carbons with specific properties or morphologies. [31,39,42,43] The research presented here continues from the work of this group, [27,28] which has shown how temperature, current density, substrate, and electrolyte variation influences the morphology of carbonate derived carbons, and how these morphological changes relate to aqueous supercapacitive performance in the materials.…”

“…In more recent years this understanding of the molten carbonate system has paved the way for an increased understanding of both the mechanism of carbon formation from molten carbonate salts, [39][40][41] and for the application of molten carbonate reduction in attempts to produce carbons with specific properties or morphologies. [31,39,42,43] The research presented here continues from the work of this group, [27,28] which has shown how temperature, current density, substrate, and electrolyte variation influences the morphology of carbonate derived carbons, and how these morphological changes relate to aqueous supercapacitive performance in the materials. [27,28] This has indicated that electrochemical performance in aqueous systems is at its highest for materials showing elevated amorphous character, which contributes to increased double layer formation, [28] and high oxygen functionalization, which leads to high pseudo-capacitance.…”