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Hydrofluorocarbon (HFC) working fluid with high global warming potential are step out of the stage of history due to the intensifying global greenhouse effect. Supercritical water gasification (SCWG), an effective and clean waste disposal method, may have better potential for the conversion of waste HFCs working fluid. ReaxFF reactive molecular dynamic and density functional theory method are used in this work to investigate the SCWG mechanism of HFC-245fa. The results indicate that the main products of HFC-245fa SCWG are high value-added chemicals and fuels such as CO, CO 2 , H 2 , and HF. During the gasification process, almost 100 % of the F atoms in HFC-245fa have the potential to become HF, which means that the SCWG method has a strong defluorination effect. The generation of H 2 molecules is promoted and the formation of CO molecule is inhibited in the presence of H 2 O molecules. More importantly, hydrogen bonds are formed between HFC-245fa and H 2 O molecules, which results in the dissociation of HFC-245fa is improved by the SCWG environment. This work provides an available and environmentally friendly route for the efficient conversion of waste HFCs to fuels. [Display omitted] • Supercritical water gasification method has a better defluorination effect. • Almost 100 % of the F atoms in HFC-245fa have the potential to become HF. • Hydrogen bonds promote the decomposition of HFC-245fa and H 2 O molecules. • HF, H 2 and CO rich products could be selectively produced. [ABSTRACT FROM AUTHOR]

A main hurdle for the commercial application of lithium–sulfur (Li–S) batteries lies in inadequate loading of sulfur due to a huge volume change over charging–discharging, poor electric conductivity of sulfur and associated sulfides, and the shuttling effect of lithium polysulfides (LiPS). Herein, a universal "three‐region" configuration including: Region I (sulfur source region), Region II (LiPS electrocatalysis region), and Region III (multi‐functional shield) for high‐areal capacity Li–S batteries is proposed. Mechanism of the configuration including the competitive relationship between Region II and Region III based on the Sabatier principle is further confirmed through density functional theory theoretical simulation and a series of in situ experimental methods. Compared with a conventional mechanical mixing electrode structure, it is demonstrated that the orderly integration "three‐region" configuration is able to prevent shuttling of LiPS effectively, which delivers high gravimetric energy density at the sulfur loading of 10.7 mg cm−2. Furthermore, a pouch cell achieves a high capacity of 148.15 mAh at a sulfur loading of 108 mg, which is by far higher than that of most previous batteries and pouch Li–S cells. Impressively, with bending and even partial damage, the pouch cell can still work normally, showing considerable safety. [ABSTRACT FROM AUTHOR]

Electrocatalytic hydrogen evolution reaction Process on the Pd/Nb 2 CT x. [Display omitted] • Pd/Nb 2 C be modified by different surface functional groups. • F-terminated Pd/Nb 2 C shows excellent HER performance. • F-terminated Pd/Nb 2 C weakens hydrogen hydrogen adsorption. • Suitable hydrogen adsorption is beneficial the HER. MXene is an emerging two-dimensional high-performance electrode material with various surface terminations during the preparation process, where the influence of these surface functional groups on the catalytic performance of MXene supported metal nanocatalysts receives only limited attentions. In this work, the hydrogen evolution reaction (HER) performance of Nb 2 CT x (T represents different functional groups) supported Pd nanocatalysts are studied via experiment and theoretical calculation. Different reagents are adopted to treat the Nb 2 C followed by loading Pd nanoparticles (NPs) in experiment. The Pd/Nb 2 C-HF exhibits outstanding HER performance compared to the Pd/Nb 2 C-H 2 SO 4 and Pd/Nb 2 C-HNO 3. The density functional theory calculations reveal that the modulation of electronic distribution of Pd NPs is observed by varying the surface functional groups and thus results in different HER performances. The F functional group in the Pd/Nb 2 C-HF is beneficial to decreasing the charge-transfer resistance and weakening the hydrogen adsorption. This study opens up a new route for designing electrocatalysts via changing surface terminations on MXene materials with enhanced HER performance. [ABSTRACT FROM AUTHOR]

Auxiliary acceptor groups play a crucial role in D-A-π-A structured organic dyes. In this paper, we designed three D-A-π-A structured organic molecules based on the prototype dye QT-1 , named ME18 – ME20 , and further investigated their electronic and optical properties with density functional theory (DFT) and time-dependent DFT (TDDFT). The calculated results indicate that the scope and intensity of dyes' absorption spectra have some outstanding changes by inserting auxiliary groups. ME20 has not only 152 nm redshifts to long wave orientation, but also 78% increased oscillator strength compared to QT-1 , and its absorption spectrum broadens region even up to 1400 nm. Then, we studied the reason that the effect of the introduced different auxiliary acceptor groups in these dyes through their ground states geometries and energy levels, electron transfer and recombination rate. [ABSTRACT FROM AUTHOR]

[Display omitted] • Oxygen vacancies enhance the interaction between the support and Pd-Co NPs. • Co atom strengthens the adsorption of reactants on the Pd atoms. • Pd-Co/TiO 2 -Vo shows excellent small molecule reduction performance. Small molecules are converted into high-value products through electrochemical methods, which are considered as potential substitutes for traditional industrial methods. To reduce the use of precious metal and modulate the local environment by oxygen vacancies, Pd-Co nanoalloys supported on TiO 2 with oxygen vacancies (Vo) are prepared through a facile pyrolysis approach. The superior ORR performance is obtained comparing to the commercial Pt/C (20 wt%) catalysts in alkaline solution. Moreover, the catalyst has amazing catalytic activity for NRR. The synergistic effect of Pd-Co alloys and the Vo greatly improves the yield of NH 3 (4.11 µg/(h·cm2)) and the Faradaic efficiency (2.83%). The performance of small molecular reduction is enhanced by the strong metal-support interactions (SMSI), which agree with the density functional theory (DFT) calculations results. It is anticipated that the established nanoalloy electrocatalysts with modulation of metal–support interactions provide guidance for designing heterogeneous electrocatalysts with high efficiency. [ABSTRACT FROM AUTHOR]

• Supercritical water gasification mechanism of R410A is studied. • Gasification process of R410A in supercritical water is described. • Hydrogen bonds are formed between R125 and H 2 O, and between R125 and R32 molecules. • Hydrogen bonds promote the decomposition of R32 and inhibit the decomposition of R125. • HF, H 2 and CO rich products could be selectively obtained. Harmless treatment and resource utilization of the waste HFC refrigerants have gradually become the focus of attention. As a clean waste resource utilization technology, supercritical water gasification has good potential in converting waste refrigerant into high value-added chemicals and fuels. In this study, the supercritical water gasification mechanism of R410A, and the interaction mechanism between R125 and R32, and between H 2 O and R410A during the gasification process are investigated by using ReaxFF reactive molecular dynamic simulation and density functional theory calculation study. The results show that the main products obtained from the supercritical water gasification of R410A are HF, H 2 , CO and CO 2. More than 90 % of F atoms in R410A can be mineralized to form HF molecules. H 2 and CO are two important syngas products during the supercritical water gasification process. Hydrogen bonds are generated between R125 and H 2 O molecules and between R125 and R32 molecules, which leads to the decomposition of R125 molecules more easily, and the decomposition of R32 molecules more difficult. This work provides a possible way to convert waste HFC refrigerant mixture into high value-added chemicals and syngas. [ABSTRACT FROM AUTHOR]

[Display omitted] • Development of a slab model for alumina-loaded Pt/Ba, considering the effects of both sites simultaneously. • The species exchange process of nitrogen-containing species between proximate Ba and Pt sites is different from the conventional view. • A good linear relationship between NOx adsorption energy and its migration energy barrier. • Detailed electronic structure analysis reveals the reason in essence. Based on density functional theory (DFT) calculations, NO x tends to migrate from Ba to Pt sites within the Lean NO x trap (LNT), rather than reacting at Pt sites before migrating to Ba sites for storage as traditionally believed. Compared with NO and N 2 O, NO 2 has the highest migration energy barrier, and there is a good linear relationship between the adsorption energy of NO x and its migration energy barrier. Furthermore, the essential cause of the above phenomenon is revealed. This study contributes to the exchange of NO x between noble metal catalytic sites and alkaline earth metal storage sites within the LNT. [ABSTRACT FROM AUTHOR]

Pyrolysis is one of the potential way for the degradation of hydrofluorocarbons, but it is difficult to make effective use of the complex pyrolysis products. The addition of plastics can provide sufficient hydrogen source for the degradation of hydrofluorocarbons to generate the high value-added chemicals and fuels. Density functional theory calculation and reactive molecular dynamic simulation are employed to investigate the co-pyrolysis mechanism of 1,1,1,2-tetrafluoroethane and low-density polyethylene in this work. The results show that the H atoms provided by low-density polyethylene promote the defluorination reactions of 1,1,1,2-tetrafluoroethane to generate HF and short chain hydrocarbons, and the number of F atoms in HF molecules accounted for nearly 80 % of the whole reaction system, achieving a better defluorination effect. The defluorination rate of 1,1,1,2-tetrafluoroethane and plastics co-pyrolysis is more than 5 times that of pure 1,1,1,2-tetrafluoroethane pyrolysis. The main co-pyrolysis products of 1,1,1,2-tetrafluoroethane and low-density polyethylene are H 2 , HF and short chain hydrocarbons, the purpose of hydrofluorocarbons degradation into high value-added chemicals and fuels is realized in this study. This work provides a green, effective way for the conversion waste hydrofluorocarbons and waste plastics into high value-added chemicals and fuels, and achieves the conversion of waste hydrofluorocarbon refrigerants to more economical products. • Co-pyrolysis mechanism of hydrofluorocarbons and plastic is first time studied. • Co-pyrolysis process of 1,1,1,2-tetrafluoroethane and low-density polyethylene is described. • Plastic as a hydrogen donor promotes the defluorination of 1,1,1,2-tetrafluoroethane. • HF, H 2 and short chain hydrocarbons rich products could be selectively obtained. • Pyrolysis products of waste hydrofluorocarbons can be enhanced by adding plastics. [ABSTRACT FROM AUTHOR]

Recently, the substitutional incorporation of late transition metals in the "A" sublattice of MAX phases further extends the physical properties and diversity of this class of materials. In this study, the structural, electronic and elastic properties of Ti 2 AC (A = Al, Zn, Cu, Ni) were investigated using the density functional theory. The calculated results reveal that a large number of d orbital bands of Zn, Cu, and Ni atoms accumulate around −6.5 eV, −2.5 eV, and −2.0 eV, respectively, leading to stronger ionic and metallic characteristics for Ti 2 ZnC, Ti 2 CuC, and Ti 2 NiC. Three Ti 2 AC (A = Zn, Cu, Ni) phases are ductile and consequently damage tolerant, whereas Ti 2 AlC is brittle in nature. When Al is replaced by Zn, Cu, and Ni, there is a remarkable decrease of hardness and shear modulus, indicating high machinability. Ti 2 ZnC, Ti 2 CuC, and Ti 2 NiC are expected to be promising thermal barrier coating materials. • First-principles calculations reveals that Ti2AC (A = Al, Zn, Cu, Ni) phases are mechanically stable. • Lattice parameters of Ti2AC (A = Al, Zn, Cu, Ni) decrease as Al is replaced by Zn, Cu, and Ni. • The d-orbitals of Zn, Cu, and Ni atoms located at the A site contribute significantly to the electronic properties. • Three new phases Ti2AC (A = Zn, Cu, Ni) are ductile and consequently damage tolerant. • Ti2ZnC, Ti2CuC, and Ti2NiC are expected to be promising thermal barrier coating materials. [ABSTRACT FROM AUTHOR]