Carbon dioxide conversion into useful products has been gaining considerable attention as a global‐warming‐mitigation technique. The electrochemical conversion of CO2 into high‐value chemicals involves the utilization of electrical energy in the presence of an effective catalyst. The process products depend on the number of transferred electrons during the reaction and the characteristics of the electrode. Recently, electrodes coupled with active catalysts have been used to convert CO2 into valuable products including formic acid, hydrocarbons, and syngas. This review offers an overview of the recent literature on the electrochemical conversion of CO2 to valuable products, with an emphasis on the production of formate/formic acid. In addition, it compares the main features of electrochemical conversion to other techniques and summarizes their key advantages. It also provides future perspective for research and development, such as the need for novel and selective catalysts to obtain high conversion and product yield with low energy consumption.

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The effects of a hydrogen bond acceptor and hydrogen bond donor on carbon dioxide absorption via natural deep eutectic solvents were studied in this work. Naturally occurring non-toxic deep eutectic solvent constituents were considered; choline chloride, b-alanine, and betaine were selected as hydrogen bond acceptors; lactic acid, malic acid, and fructose were selected as hydrogen bond donors. Experimental gas absorption data were collected via experimental methods that uses gravimetric principles. Carbon dioxide capture data for an isolated hydrogen bond donor and hydrogen bond acceptor, as well as natural deep eutectic solvents, were collected. In addition to experimental data, a theoretical study using Density Functional Theory was carried out to analyze the properties of these fluids from the nanoscopic viewpoint and their relationship with the macroscopic behavior of the system, and its ability for carbon dioxide absorption. The combined experimental and theoretical reported approach work leads to valuable discussions on what is the effect of each hydrogen bond donor or acceptor, as well as how they influence the strength and stability of the carbon dioxide absorption in deep eutectic solvents. Theoretical calculations explained the experimental findings, and combined results showed the superiority of the hydrogen bond acceptor role in the gas absorption process, with deep eutectic solvents. Specifically, the cases in which choline chloride was used as hydrogen bond acceptor showed the highest absorption performance. Furthermore, it was observed that when malic acid was used as a hydrogen bond donor, it led to low carbon dioxide solubility performance in comparison to other studied deep eutectic solvents. The cases in which lactic acid was used as a hydrogen bond donor showed great absorption performance. In light of this work, more targeted, specific, deep eutectic solvents can be designed for effective and alternative carbon dioxide capture and management.

In this paper, we report high pressure experimental measurements and detailed density functional theory (DFT) as well as molecular dynamic (MD) simulations of methane (CH 4 ) solubility in natural deep eutectic solvents (NADESs) that were prepared by using alanine (Al), betaine (Be), and choline chloride (ChCl) used as hydrogen bond acceptors (HBA) and lactic acid (La), malic acid (Ma), and phenylacetic acid (Paa) used as hydrogen bond donors (HBD). Experiments were performed on Al:La, Be:La, ChCl:La, ChCl:Ma, and ChCl:Paa systems up to 50 bar at 298.15 K. Meanwhile, this work includes the quantum theory of atoms in molecules (QTAIM) calculations that allow quantifying and characterizing the short-range interactions of studied systems, which is reported for the first time for NADESs and CH 4 interactions. Furthermore, MD simulations shed light onto the characteristics of intermolecular forces, particularly for hydrogen bonding, molecular arrangements in the liquid phases, and their role in fluid's properties. The presented results showed that the studied NADESs can be used for selective CO 2 /CH 4 separation in gas processing applications.