Electrochemical Growth of High-Strength Carbon Nanocoils in Molten Carbonates

Abstract

The reported mechanical strength of carbon nanocoils (CNCs) obtained from traditional preparation of catalytic acetylene pyrolysis is far below its theoretical value. Herein, we report a molten salt electrolysis method that employs CO3 2– as feedstock to grow CNCs without using metal catalyst. We meticulously mediate the alkalinity of molten carbonate to tune the electrochemical reduction of CO3 2– on graphite electrode to selectively grow CNCs in Li2CO3–Na2CO3–K2CO3–0.001 wt %Li2O. Graphite substrate, current density, and alkalinity of molten salt dictate the growth of CNCs. In addition, the electrolytic CNCs shows a spring constant of 1.92–39.41 N/m and a shear modulus of 21–547 GPa, which are 10–200 times that of CNCs obtained from catalyst-assisted gas-to-solid conversions. Overall, this paper opens up an electrochemical way to prepare CNCs through liquid-to-solid conversion without using catalysts and acetylene, providing new perspectives on green synthesis of 1D carbon nanomaterials with high mechanical strength.

Plastic Shavings by Laser: Peeling Porous Graphene Springs for Multifunctional All‐Carbon Applications

“…[ 44 ] The equation for the elasticity coefficient of a helical spring, [ 44 ] although the detailed geometry of the spring is not completely matched, estimates that the shear modulus of the resulting LIG‐S is ≈0.3 GPa (Summary of electrical and mechanical properties concerned with free‐standing LIGs is described in the Table S1, Supporting Information). This is considerably lower than the shear modulus of fully dense isotropic graphite [ 45 ] or other carbon products from pyrolysis, [ 46 ] but comparable to that measured from LIG converted from a PI substrate [ 37 ] when the effect of volume fraction porosity on the shear modulus [ 45 ] is reflected. At the same time, the minor suppression of the spring constant in the direction of compression compared to the tensile case, as shown in the inset, appears to be associated with the porosity of the specific LIG‐S.…”

Selective CO2 Electroreduction with Enhanced Oxygen Evolution Efficiency in Affordable Borate-Mediated Molten Electrolyte

“…As shown in the Raman spectrum (Figure f), the noticeable G band and 2D band located at 1580 and 2700 cm –1 , respectively, further reveal that the carbon nanocoils deliver graphitic features. Similar one-dimensional nanostructured carbon nanofibers/nanotubes can also be found in borate-containing and Li 2 O-containing lithium carbonates. − Considering that the oxygen content of carbonaceous materials plays an important role in their nanostructures and crystallinity, we speculate that the borates could help modulate the carbon growth environment’s oxo-acidity by regulating adjacent oxygen content and facilitating an ordered arrangement of carbon atoms in the basal planes, which needs systematic investigation in the future. It should be pointed out that the contrast between onset potential and theoretical potential for borate-involved CO 2 RR was only tens mV, implying that the overpotential to initiate CO 2 RR should be low.…”

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

“…6h). 102 Besides using CO 2 as a carbon source, traditional polymer carbon precursors are also available for molten salt electrolysis to yield carbon-based materials. Weng et al reported the syn-thesis of a Si/C hybrid via pyrolysis-cum-electrolysis in molten NaCl-CaCl 2 at 800 °C using SiO 2 @polydopamine (SiO 2 @PDA) as both silicon and carbon precursors.…”