Search

• Three possible pathways for bicarbonate generation were investigated based on DFT. • Base-catalyzed CO 2 hydration is dominant in [N 1111 ][Gly]/EtOH aqueous system. • Water effect on phase change behavior is analyzed from hydrogen bonding view. • Water content of 5 wt% promotes products aggregation in favor of phase change. Ionic liquids-based anhydrous biphasic absorbents have the potential to lower the energy consumption for CO 2 capture. Recent experimental studies have revealed that the presence of water in [N 1111 ][Gly]/EtOH system leads to generation of a new CO 2 -product – bicarbonate and affects the phase change behavior. However, the reaction pathway for bicarbonate formation remains unclear. In this work, the reaction pathways were investigated in depth through quantum chemical calculations employing density functional theory, with reaction rate constants determined via transition state theory. Among the three possible reaction pathways, the base-catalyzed CO 2 hydration reaction prevailed, i.e. a one-step reaction involving [Gly]-, H 2 O, and CO 2. An H atom in H 2 O was transferred to [Gly]-'s amino group, forming protonated [Gly]-, and hydroxide combined with CO 2 to generate bicarbonate. Additionally, molecular dynamics simulations were conducted to understand the phase change behaviors with varying water content. When water content exceeded 5 wt%, an increased water content led to reduced hydrogen bonding among products and enhanced hydrogen bonding of products-solvent with the solvent, diminishing product self-aggregation. No phase change behavior were observed at water contents up to 80 wt%. This study could well explain the experimental phenomena of water effect on CO 2 absorption in [N 1111 ][Gly]/EtOH, providing theoretical references for application of ILs-based anhydrous biphasic absorbent. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mo-based MXene is first applied as a cathode catalyst for Li-CO 2 batteries. • An innovative surface modification strategy, mild oxidation by CO 2 , is employed. • The catalyst optimizes the growth and decomposition of discharge products. • This MoO 2 @Mo 2 C-based Li-CO 2 battery outperforms most other MXene-based catalysts. The lithium-carbon dioxide (Li-CO 2) batteries hold promise for energy storage, given their capacity to capture and convert carbon dioxide (CO 2). However, the practical application of Li-CO 2 batteries continues to face substantial obstacles caused by sluggish CO 2 reduction/evolution kinetics, resulting in high overpotential and short lifespan. This work presents the fabrication of a highly effective MoO 2 @Mo 2 C heterostructure hybrid catalyst using a CO 2 oxidation strategy. This strategy integrated (in-situ) MoO 2 onto the surface of two-dimensional (2D) Mo 2 C MXene, enhancing catalytic activity while preserving 2D electron/ion pathways. As a result, the MoO 2 @Mo 2 C, when used as a catalyst in Li-CO 2 battery showcased a discharge capacity of 20790.8 mAh g−1 at a current density of 200 mA g−1. Notably, it achieved a long cycling life of 230 cycles at a cutoff capacity of 1000 mAh g−1 with a voltage gap as low as 1.85 V, which was significantly superior to that of a pristine Mo 2 CT x catalyst (3.61 V after twenty cycles). This work provides critical insights into the design of MXenes-based high-performance catalysts for advanced Li-CO 2 batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] • Excellent activity and selectivity of CO 2 -to-CH 4 conversion is realized by MIS. • The ultrathin insulator layer significantly expedites the interfacial electrons tunneling. • The MIS promotes rate-determining step from *COOH to *CO to produce CH 4. A metal–insulator-semiconductor (MIS) ternary photo-system was intricately crafted through precise amalgamation polyvinylpyrrolidone (PVP)-capped metal Cu with typical covalent triazine framework CTF-1 via electrostatic self-assembly. The 2 % Cu-PVP-CTF exhibited an impressive CH 4 yield of 80.7 μmol·g−1·h−1 with selectivity of 96.8 % under visible light, representing a 2.3-fold and 112-fold improvement over Schottky-type Cu-CTF and pristine CTF-1, respectively. In-situ XPS and VASP-diff calculations unfolded that the ultrathin PVP insulating layer significantly expedited interfacial charges tunneling, corroborated by smaller lifetime τ 2 determined via femtosecond transient absorption spectroscopy. The intermediates of paramount importance in CO 2 reduction like *COOH and *HCHO were meticulously monitored by in-situ Fourier infrared spectroscopy. DFT calculations elucidated that Cu-PVP-CTF was notably more adept at facillitating the rate-determining step (*COOH → *CO) to produce CH 4 than Cu-CTF. This work tamps the groundwork for conceptional roadmap in designing novel MIS photo-system for CO 2 conversion. [ABSTRACT FROM AUTHOR]