## 3 Results and Discussion
### The Catholic Production of Carbon
The calculated results shown in the above table indicate that the generation of lithium metal from Li\({}_{2}\)CO\({}_{3}\) needs a higher electrolysis potential, and the electrodeposition of Li\({}_{2}\)CO\({}_{3}\) into carbon is much more favorable in comparison to Na\({}_{2}\)CO\({}_{3}\) and K\({}_{2}\)CO\({}_{3}\). Therefore, Li\({}_{2}\)CO\({}_{3}\) is the most unfavorable ingredient for metal precipitation and becomes the main body of eutectic molten salts. It has been reported that CO\({}_{2}\) can be transformed into solid carbon in molten salts under N\({}_{2}\), CO\({}_{2}\), or Ar [30; 31]. Under the appropriate conditions, regardless of the gaseous environment (N\({}_{2}\), CO\({}_{2}\), or Ar), there is a transformation of CO\({}_{3}^{2-}\) ions into nonvalent carbon in molten lithium-rich carbonate. The electrolysis system shows a \(\
eg 95\%\) current efficiency in Li\({}_{2}\)CO\({}_{3}\)-Na\({}_{2}\)CO\({}_{3}\)-K\({}_{2}\)CO\({}_{3}\) under Ar, while it is only \(67\%\) under CO\({}_{2}\) due to the thermal reductive reaction of carbon with CO\({}_{2}\) to CO [29]. Although the increasing CO\({}_{2}\) partial pressure can enhance the carbon electrodeposition rate, it will lead to a huge loss of energy. Argon exhibits an excellent performance in preventing or inhibiting the corrosion of electrodes, and it can also separate the gaseous oxidation products. With that in mind, Li\({}_{1.43}\)Na\({}_{0.26}\)K\({}_{0.21}\)CO\({}_{3}\) is the optimal electrolyte to make the whole process of transforming CO\({}_{2}\) into carbon products in the atmosphere of argon work effectively. Figure 1 shows a CV curve (cyclic voltammetry) of an Ni anode and Fe cathode in t Li\({}_{1.43}\)Na\({}_{0.26}\)K\({}_{0.21}\)CO\({}_{3}\) at 550 \({}^{\circ}\)C. No reduction peak is observed between 0 V and 1 V at any scanning rate in Figure 1a, suggesting that no reduction product is obtained in the low-potential range. The first reduction peak, R1, appears at 1.5 V, indicating carbon deposition. With the continually rising potential, the following reduction peak, R2 at 2.3 V, represents the generation of CO from the molten carbonates. It can be seen from the reduction peak R3 that the maximal electrolysis potential is 2.8 V. Otherwise, the alkaline metals (Na and K) will be deposited on the surface of the cathode and result in wasteful power consumption. The oxidation peaks C1 and C2 clearly suggest the electrolysis dissolution of the deposited alkaline metal and carbon, which can be verified by the CVs of successive scans (Figure 1b) [32]. As shown in Figure 1b, the reduction current of R1 and the anodic current of C1 increase with the scanning cycles, which can be explained by continuous carbon deposition, resulting in the growing surface of the working electrodes [33]. Figure 1: Cyclic voltammetry recorded from an Ni anode and Fe cathode in Li\({}_{1.43}\)Na\({}_{0.26}\)K\({}_{0.21}\)CO\({}_{3}\) at 550 \({}^{\circ}\)C under consecutive cycling (**a**) in different scanning rates and (**b**) different scanning cycles at 10 mv/s. The electrolysis experiment was conducted to further investigate the carbon materials deposited on the Fe cathode in the molten Li\({}_{1.43}\)Na\({}_{0.26}\)K\({}_{0.21}\)CO\({}_{3}\) with the Ni anode at 550 \({}^{\circ}\)C, and the result is shown in Figure 2. The cell-current curve in Figure 2 was recorded during the electrolysis reaction at 2.0 V with an electrochemical workstation, and the electrode photos obtained at the different reaction intervals during the electrolysis process at 2.0 V are shown on the timeline. As can be seen in the digital photo of the cathodes, a layer of carbon particles is observed on the surface of the Fe cathode, revealing an increasing tendency of carbon products as the reaction time increases. Obviously, cell-current values also increase as time goes on, which is consistent with the anticipated increase in the electrode's surface area.