Highly Efficient Carbon Monoxide Capture by Carbanion-Functionalized Ionic Liquids through C-Site Interactions.

A novel method for the highly efficient and reversible capture of CO in carbanion-functionalized ionic liquids (ILs) by a C-site interaction is reported. Because of its supernucleophilicity, the carbanion in ILs could absorb CO efficiently. As a result, a relatively high absorption capacity for CO (up to 0.046 mol mol-1 ) was achieved under ambient conditions, compared with CO solubility in a commonly used IL [Bmim][Tf2 N] (2×10-3  mol mol-1 ). The results of quantum mechanical calculations and spectroscopic investigation confirmed that the chemical interaction between the C-site in the carbanion and CO resulted in the superior CO absorption capacities. Furthermore, the subsequent conversion of captured CO into valuable chemicals with good reactivity was also realized through the alkoxycarbonylation reaction under mild conditions. Highly efficient CO absorption by carbanion-functionalized ILs provides a new way of separating and converting CO.

Multi-Molar Absorption of CO2 by the Activation of Carboxylate Groups in Amino Acid Ionic Liquids.

A new strategy for multi-molar absorption of CO2 is reported based on activating a carboxylate group in amino acid ionic liquids. It was illustrated that introducing an electron-withdrawing site to amino acid anions could reduce the negative inductive effect of the amino group while simultaneously activating the carboxylate group to interact with CO2 very efficiently. An extremely high absorption capacity of CO2 (up to 1.69 mol mol(-1) ) in aminopolycarboxylate-based amino acid ionic liquids was thus achieved. The evidence of spectroscopic investigations and quantum-chemical calculations confirmed the interactions between two kinds of sites in the anion and CO2 that resulted in superior CO2 capacities.

Insight into the Surface Reconstruction-Induced Structure and Electrochemical Performance Evolution for Ni-Rich Cathodes with Postannealing after Washing.

Ni-rich layered LiNixCoyAlzO2 (NCA, x ≥ 0.8) oxides have attracted wide attention as cathode materials for lithium-ion batteries due to their higher energy density and lower cost. However, the increase in the capacity for Ni-rich cathodes can cause faster capacity decay and increase sensitivity to ambient air exposure during the storage process. Especially, the residual lithium on the surface of Ni-rich cathodes will cause severe flatulence during cycling which greatly reduces the safety performance of the battery. Washing is an effective method to reduce residual lithium, but it will seriously damage the surface phase structure of Ni-rich materials. Here, we introduce a designed method involving two steps, washing and high-temperature annealing, which can ingeniously modify the surface phase structure of Ni-rich cathodes. The results show that the residual lithium content can be significantly reduced. The thin NiO-like rock-salt phase formed on the surface of Ni-rich cathode annealed at 600 °C improves the diffusion kinetics of Li+, reduces the polarization, and improves the electrochemical performance of Ni-rich materials, while the thick spinel-like phase formed at 400 °C hinders the diffusion kinetics of Li+, significantly increases the polarization, and eventually leads to the structural degradation of Ni-rich materials. As a result, the discharge capacity of the cathode annealed at 600 °C still retains 174.48 mA h g-1 after 100 cycles, with a capacity retention of 92.04%, much larger than the cathode annealed at 400 °C, for which the discharge capacity drops to 107.77 mA h g-1, with a capacity retention of 65.78%.

Phenothiazine-anthraquinone donor-acceptor molecules: synthesis, electronic properties and DFT-TDDFT computational study.

Two donor-acceptor molecules with different pi-electron conjugative units, 1-((10-methyl-10H-phenothiazin-3-yl)ethynyl)anthracene-9,10-dione (AqMp) and 1,1'-(10-methyl-10H-phenothiazine-3,7-diyl)bis(ethyne-2,1-diyl)dianthracene-9,10-dione (Aq2Mp), have been synthesized and investigated for their photochemical and electrochemical properties. Density functional theory (DFT) calculations provide insights into their molecular geometry, electronic structures, and properties. These studies satisfactorily explain the electrochemistry of the two compounds and indicate that larger conjugative effect leads to smaller HOMO-LUMO gap (Eg) in Aq2Mp. Both compounds show ICT and pi --> pi* transitions in the UV-visible range in solution, and Aq2Mp has a bathochromic shift and shows higher oscillator strength of the absorption, which has been verified by time-dependent DFT (TDDFT) calculations. The differences between AqMp and Aq2Mp indicate that the structural and conjugative effects have great influence on the electronic properties of the molecules.