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Potassium-ion batteries (KIBs) are considered a promising candidate for energy storage owing to their low cost and similar "rocking chair" mechanism to lithium-ion batteries. However, there is a great lack of suitable and high working performance electrode materials for KIBs. Herein, first principles calculations based on density functional theory (DFT) are applied to evaluate the potential of the B7N5 monolayer as an anode material for KIBs. It is found that B7N5 shows negative adsorption energies for Li/Na/K on its surface. Besides, the B7N5 monolayer can effectively achieve double-layer adsorption for K atoms on both sides of the monolayer surface, while one-layer adsorption for Li and Na. Thus, B7N5 exhibits an ultra-high theoretical capacity of 1471.5 mA h g−1 for KIBs, which is almost the highest value for the anode materials reported in the literature. And the attractive capacity for KIBs is mainly contributed by the multiple empty electron orbitals of the constituting elements of B7N5 and the small distance mismatch. In addition, K atoms display high diffusivities on B7N5 with low energy barriers of 0.10 eV, and the open circuit voltages of 0.14 V for KIBs are also smaller compared with previous research. It is also shown that after adsorbing K, the semiconducting B7N5 monolayer is transformed to a metallic state with good conductivity. Furthermore, despite the large size of K+, the maximum change in the lattice constant of B7N5 is only 1.32%, indicating structural stability and ensuring good cycling stability for KIBs. The above-mentioned results suggest that B7N5 is a potential anode material for KIBs. [ABSTRACT FROM AUTHOR]

The development of novel high specific capacity anode materials is urgently needed for rechargeable metal ion batteries. Herein, S-functionalized V2B as the electrode material for Li/Na/K ion batteries are comprehensively investigated using first-principles calculations. Specifically, V2BS2 was verified with good electrical conductivity via band structure and density of states calculations. Phonon dispersion and ab initio molecular dynamic simulations were performed and confirmed the dynamic and thermal stability of V2BS2. The use of V2BS2 with a high theoretical specific capacity of 606 mA h g−1 for lithium ion batteries (LIBs) due to the bilayer adsorption of Li atoms is encouraging, which is attributed to the double empty orbitals of the S atoms and small lattice mismatch (1.5%) between the Li layers and substrate. Furthermore, dendrite formation would be well prohibited and safety issues for battery operation would be ensured for V2BS2 as electrode materials because of the low open circuit voltage with 0.37 V. The high charge/discharge rate for LIBs is also achievable owing to the high mobility of adatoms on the surface of V2BS2. Our work not only finds use as a promising material for the field of energy storage, but also provides constructive design strategies for developing high performance anode materials for rechargeable metal ion batteries. [ABSTRACT FROM AUTHOR]

In this study, an efficient catalytic system composed of deep eutectic solvents (DESs) was developed by adjusting the basicity of hydrogen bond donors (HBDs) to synthesize poly(isosorbide) carbonate (PIC) with high weight average molecular weight (Mw). It was demonstrated that the Mw of PIC prepared by using nearly neutral [EminOH]Cl–2EG was the highest. The results of the transesterification kinetics with different catalysts supported that the transesterification rate was significantly promoted as the basicity of DESs increased but their strong alkalinity inhibited the Mw of PIC. Therefore, the degradation of PIC was investigated to reveal the mechanism of the influence of basicity on the molecular weight of PIC. The strong alkalinity of DESs would cause the depolymerization of the macromolecular chains and ultimately limit the molecular weight of the product, proving the experimental fact that a near-neutral catalyst was more conducive to the Mw of PIC. Finally, a reasonable mechanism of synergistic catalysis was proposed based on 1H NMR spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and experimental results. The metal-free, low-cost, high catalytic activity DES catalyst involved here is a practical candidate for advanced bio-based polycarbonate. [ABSTRACT FROM AUTHOR]

Cleavage of aryl ether (Caryl–O) bonds is crucial for the conversion and value-added utilization of lignin and its derivatives, but remains extremely challenging under mild conditions due to strong Caryl–O linkages. In this study, the Caryl–O bond breaking is achieved through electrocatalytic oxidation of four phenolic lignin model compounds with typical Caryl–O bonds, i.e., 4-ethoxyphenol (EP), 4-phenoxyphenol (PP), p-benzyloxyphenol (PBP), and 2-(2-phenylethoxy)phenol (2-PEP), in a protic ionic liquid [BSO3Hmim][OTf]–H2O electrolyte, and the electrocatalytic oxidation mechanism is also fully explored. The effects of H2O on the viscosity and conductivity of the [BSO3Hmim][OTf] ionic liquid system, as well as the solubility and diffusion coefficients of O2 and the four lignin substrates, are investigated to optimize the optimal ratio of the electrolyte system composed of [BSO3Hmim][OTf] and H2O. Electrochemical oxidation–reduction behaviors of the four lignin substrates in the [BSO3Hmim][OTf]–H2O system and the effect of O2 and N2 atmospheres on degradation are studied in detail by using cyclic voltammetry (CV) curves. Finally, by combining the analysis of degradation products with isotope labeling experiments, the C–O bond cleavage mechanism is obtained, which mainly involves direct and indirect oxidation. Specifically, under a N2 atmosphere, the substrates are oxidized directly on the RuO2-IrO2/Ti mesh electrode through Caryl–O bond splitting to form quinone and carbonium ions, while under an O2 atmosphere, apart from the direct oxidation on the electrode, indirect oxidation of the lignin substrates also occurs through in situ generated H2O2. This study may provide some insight into developing effective strategies for efficient utilization of lignin under mild conditions. [ABSTRACT FROM AUTHOR]

In this study, a series of high-activity imidazole-based dicationic ionic liquids (DILs) were designed and prepared as efficient catalysts for balancing the reactivity between the endo-hydroxyl group (endo-OH) and the exo-hydroxyl group (exo-OH) of isosorbide (ISO) to synthesize high molecular weight poly(isosorbide carbonate) (PIC). Meanwhile, the thermal performance of PIC was precisely optimized by regulating the chain configuration. The results showed that when the trace amounts (4.5 × 10−5 based on the ISO molar amount) of bis-(3-methyl-1-imidazole)-ethylene dibromide ([C2(Min)2][Br]2) were used, the weight average molecular weight (Mw) of PIC reached 98 700 g mol−1. It could be concluded from the results of the experiment and the stimulation that the high catalytic activity of DILs was attributed to the strong electrostatic interaction between the cation and the substrate and the effective balance of the reactivity of the endo-OH and the exo-OH. Furthermore, we found that the reduction of hydroxyl groups in the terminal groups and the increase of endo–endo (a1) structure in the repeating unit improved the thermal properties of PIC. Finally, 1H NMR, Fourier infrared spectroscopy, and density functional theory (DFT) calculations were used to verify the reaction process through anion and cation multi-site synergistic effect and a possible electrophilic–nucleophilic reaction mechanism was successfully obtained. [ABSTRACT FROM AUTHOR]

Synthesis of bioderived high-molecular-weight polycarbonates under metal-free condition is particularly challenging. Here, a green synthetic strategy of bio-based poly(isosorbide carbonate) (PIC) from renewable monomer isosorbide (ISB) and dimethyl carbonate (DMC) was developed by using organo-catalysts, which avoided the use of toxic and metal-containing chemicals. Due to high catalytic activity of the organo-catalysts, the reactivity of ISB and selectivity of carboxymethylated products were improved significantly, resulting in high-molecular-weight PIC. By using 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as catalyst, an oligomer with [–OC(O)OCH3]/[–OH] ratio of 1.56 and PIC with weight-average molecular weight of 53 200 were obtained, which indicated that both ISB and DMC were effectively activated by TBD according to our proposed bifunctional activation mechanism. Furthermore, one-pot synthesis of copolymeric poly(diol-co-isosorbide carbonate)s from ISB, DMC and various diols was achieved, where the secondary hydroxyl group of ISB and the primary hydroxyl group of diols were dually activated by TBD, which has not been reported to the best of our knowledge. [ABSTRACT FROM AUTHOR]

The conversion of biomass and carbon dioxide to plastics is one of the key solutions to reduce the greenhouse effect and alleviate the petroleum resource depletion. However, there is still a lack of bioderived polymers with high molecular weights and excellent performance and their corresponding green synthesis processes, which limits the potential of bioderived polymers to replace petroleum-based polymers. In this study, an eco-friendly synthetic process for bioderived polycarbonate, catalyzed by amino acid ionic liquids, was developed by utilizing isosorbide (ISO) and diphenyl carbonate (DPC) as reactants, derived from a renewable resource and carbon dioxide, respectively. By using 1-ethyl-3-methylimidazole lysine ([Emim][Lys]) as a catalyst, poly(isosorbide carbonate) (PIC) with the weight average molecular weight of 150 000, the highest reported so far to the best of our knowledge, was synthesized, and the Tg of PIC was up to 174 °C. The reaction mechanism was investigated using nuclear magnetic resonance (NMR) spectroscopy, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-ToF MS), and density functional theory (DFT) calculation. The remarkable catalytic performance was attributed to the fact that [Emim][Lys] could effectively activate the hydroxyl group of ISO and carbonyl group of DPC, and inhibit the formation of cyclic intermediates. Moreover, to overcome the brittleness of PIC, 1,4-butanediol (BD) and 1,4-cyclohexanedimethanol (CHDM) were introduced into PIC, and the copolycarbonate showed excellent Young's modulus, ultimate tensile strength, and elongation at break, which were 979 MPa, 57 MPa, and 145%, respectively, and were comparable to the commercial petroleum-based polycarbonates. Such a process provides further industrial prospects for the next generation of bioderived polycarbonate. [ABSTRACT FROM AUTHOR]

Lignocellulosic materials were conventionally treated as wastes for disposal, but have now become very important in modern life due to their great roles in the supply of renewable resources. Recently, significant attention has been paid to the dissolution of cellulose, hemicellulose, and lignin, and the production of chemicals and fuels from these feedstocks. It has been demonstrated that lignocellulose has great potential from a sustainable economy perspective and this field has been developing rapidly. Thus, it is critical to review the recent progress in studies on the utilization of lignocellulosic materials. In particular, this work was designed to highlight recent computation-based studies on the chemistry of lignocellulosic materials, from the structural and energetic properties of individual lignocellulose components to their reaction mechanisms in various systems. Importantly, this review summarizes some major simulation studies on the utilization of cellulose, hemicellulose, and lignin via dissolution, catalytic conversion, and pyrolysis by using density functional theory, first-principles calculation, molecular dynamics simulation, and conductor-like screening models. It has been shown that the theoretical and computational investigations play a key role in the understanding of the efficient utilization of lignocellulose. [ABSTRACT FROM AUTHOR]

Selective valorization of lignin to achieve high value and commodity chemicals is attracting increasing attention. In this work, an efficient and reusable metal-based ionic liquid (MBIL) was developed for the selective tailoring of p-coumaric acid ester (pCA), a typical p-hydroxyphenyl (H) unit, into methyl p-hydroxycinnamate (MPC). Under optimized conditions and in the presence of catalyst [Bmim][FeCl4], a volatile aromatic product of 10.5 wt% was obtained, of which, 70.5% separated as pure MPC with an isolated yield of 71.1 mg g−1. FT-IR, 13C NMR, ANO and 2D HSQC demonstrated that the H unit was preferentially tailored from lignin, of which, 86.0 wt% of the H structure unit is cut off from lignin, with 70.6% being selectively converted to MPC. Further investigation demonstrated that MBIL prefers to tailor ester bonds compared to ether bonds using model compounds, and the superior catalytic ester bond cleavage performance exhibited by [Bmim][FeCl4] can be ascribed to the relatively narrow energy gap between the lignin ester bond and [FeCl4]− anion and to the comparatively low absolute binding energy between the cation and anion through DFT calculations. [ABSTRACT FROM AUTHOR]

The commercialization of fuel cells and metal–air batteries can only be realized if expensive and scarce platinum-based catalysts are replaced by lower cost, efficient, and durable catalysts for the oxygen reduction reaction (ORR). Along with intensive research efforts in developing low-cost, metal-free catalysts to replace platinum-based catalysts, heteroatom doped graphitic carbon materials (especially graphene and carbon nanotubes) have been demonstrated to show superior ORR performance. However, graphdiyne, another member of the carbon family, has not been completely studied as an electrocatalyst for the ORR. We demonstrate here that nitrogen and fluorine co-doped, metal-free graphdiyne exhibits comparable electrocatalytic activity to commercial Pt/C both in half-cell and full-cell (primary Zn–air battery) tests, regarding its onset potential and limiting current density. Moreover, the new catalyst has better stability, as well as a higher tolerance to methanol crossover and CO poisoning effects, than the commercial Pt/C. [ABSTRACT FROM AUTHOR]

A series of oxazole-fused succinimides bearing vicinal quaternary carbon centers were synthesized. This process takes place between nitroolefins and azlactones in the presence of a bifunctional chiral guanidine-sulfonamide organocatalyst, followed by a Nef-type transformation under the treatment of DMAP/Ac 2 O. Several control experiments were conducted to propose the mechanism.

Potassium-ion batteries (KIBs) are considered a promising candidate for energy storage owing to their low cost and similar "rocking chair" mechanism to lithium-ion batteries. However, there is a great lack of suitable and high working performance electrode materials for KIBs. Herein, first principles calculations based on density functional theory (DFT) are applied to evaluate the potential of the B 7 N 5 monolayer as an anode material for KIBs. It is found that B 7 N 5 shows negative adsorption energies for Li/Na/K on its surface. Besides, the B 7 N 5 monolayer can effectively achieve double-layer adsorption for K atoms on both sides of the monolayer surface, while one-layer adsorption for Li and Na. Thus, B 7 N 5 exhibits an ultra-high theoretical capacity of 1471.5 mA h g -1 for KIBs, which is almost the highest value for the anode materials reported in the literature. And the attractive capacity for KIBs is mainly contributed by the multiple empty electron orbitals of the constituting elements of B 7 N 5 and the small distance mismatch. In addition, K atoms display high diffusivities on B 7 N 5 with low energy barriers of 0.10 eV, and the open circuit voltages of 0.14 V for KIBs are also smaller compared with previous research. It is also shown that after adsorbing K, the semiconducting B 7 N 5 monolayer is transformed to a metallic state with good conductivity. Furthermore, despite the large size of K + , the maximum change in the lattice constant of B 7 N 5 is only 1.32%, indicating structural stability and ensuring good cycling stability for KIBs. The above-mentioned results suggest that B 7 N 5 is a potential anode material for KIBs.

The development of novel high specific capacity anode materials is urgently needed for rechargeable metal ion batteries. Herein, S-functionalized V 2 B as the electrode material for Li/Na/K ion batteries are comprehensively investigated using first-principles calculations. Specifically, V 2 BS 2 was verified with good electrical conductivity via band structure and density of states calculations. Phonon dispersion and ab initio molecular dynamic simulations were performed and confirmed the dynamic and thermal stability of V 2 BS 2 . The use of V 2 BS 2 with a high theoretical specific capacity of 606 mA h g -1 for lithium ion batteries (LIBs) due to the bilayer adsorption of Li atoms is encouraging, which is attributed to the double empty orbitals of the S atoms and small lattice mismatch (1.5%) between the Li layers and substrate. Furthermore, dendrite formation would be well prohibited and safety issues for battery operation would be ensured for V 2 BS 2 as electrode materials because of the low open circuit voltage with 0.37 V. The high charge/discharge rate for LIBs is also achievable owing to the high mobility of adatoms on the surface of V 2 BS 2 . Our work not only finds use as a promising material for the field of energy storage, but also provides constructive design strategies for developing high performance anode materials for rechargeable metal ion batteries.