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For the global commercialization of highly efficient and stable perovskite solar cells (PSCs), it is necessary to effectively suppress the formation of various defects acting as nonradiative recombination sources in perovskite light-harvesting materials. Interfacial defects between the charge-selective layer and the perovskite are easily formed in the solution process used to fabricate perovskite films. In addition, owing to the difference in thermal expansion coefficients between the substrate and the perovskite film, internal residual tensile stress inevitably occurs, resulting in increased nonradiative recombination. Herein, a simple compositional engineering scheme for realizing efficient and stable PSCs, which incorporates acetamidinium bromide (AABr) as an additive into the MAPbI3 lattice, is proposed. As an additive, AABr has been found to provide synergistic multiple passivation for both internal and interfacial defects. AABr was found to effectively release the tensile strain of the MAPbI3 film by forming a structure stabilized by NH–I hydrogen bonds, as evidenced by calculations based on density functional theory (DFT). Furthermore, the incorporated AABr additives created a charge carrier recombination barrier to enhance charge collection capability by reducing interfacial defects. Accordingly, a power conversion efficiency (PCE) of 20.18% was achieved using a planar device employing AABr-incorporated MAPbI3. This was substantially higher than the 18.32% PCE of a pristine MAPbI3-based device. Notably, unencapsulated PSCs using AABr-incorporated MAPbI3 absorbers exhibited excellent long-term stability, maintaining >95% of initial PCE up to 1200 hours in ambient air.

Despite the promise of pyrenetetrone derivatives as insoluble organic cathode compounds for lithium-ion batteries, there is limited information on their electrochemical characteristics. Herein, a highly reliable computational protocol is employed to systematically explore the redox properties and theoretical performances of pyrenetetrone derivatives. This comprehensive analysis reveals that the electrochemical redox properties of pyrenetetrone derivatives at fully charged states are determined by complementary contributions from key factors, such as dopant electronegativity, electrostatic potential of the central backbone, and interatomic electronic flow. In contrast, dopant electronegativity becomes a dominant factor for tuning the redox behaviors of these organic compounds during the Li-involved discharging process, indicating the potential of boron-doped compounds for high-performance cathodes. Further investigation highlights that the entire discharging process can be summarized as Li-induced continuous reduction in electron affinity terminated by a sudden increase in solvation energy (depending on dopant electronegativity), which emphasizes the importance of solvation energy in determining cathodic deactivation.

The effect of ultraviolet-ozone (UVO) irradiation on amorphous (am) SnO2 and its impact on the photoconversion efficiency of MAPbI3-based perovskite solar cells were investigated in detail. UVO treatment was found to increase the amount of chemisorbed oxygen on the am-SnO2 surface, reducing the surface energy and contact angle. Physicochemical changes in the am-SnO2 surface lowered the Gibbs free energy for the densification of perovskite films and facilitated the formation of homogeneous perovskite grains. In addition, the Fermi energy of the UVO-treated am-SnO2 shifted upwards to achieve an ideal band offset for MAPbI3, which was verified by theoretical calculations based on the density functional theory. We achieved a champion efficiency of 19.01 % with a statistical reproducibility of 17.01 ± 1.34 % owing to improved perovskite film densification and enhanced charge transport/extraction, which is considerably higher than the 13.78 ± 2.15 % of the counterpart. Furthermore, UVO-treated, am-SnO2-based devices showed improved stability and less hysteresis, which is encouraging for the future application of up-scaled perovskite solar cells.

Despite the potential of organic materials for cathodes in lithium-ion batteries arising from their eco-friendly production processes and structural flexibility, their redox properties are not comprehensively unveiled. In this work, the redox properties and performances for chloranil derivatives with one to four cyano functional group(s) are studied to assess their potential as high-potential organic cathode materials. The well-designed computational protocol is employed to reliably predict the redox behaviors for the organic compounds. This investigation highlights synergistic effects of carbonyls and cyanides on improving the electrochemical properties, exhibiting the remarkably high open-circuit redox potential (4.50 ​V vs. Li/Li+) and theoretical performances (515 ​mA ​h/g and 1517 ​mWh/g) for the chloranil derivative with four cyano functionalities. Furthermore, this study emphasizes that the redox potential of a chloranil derivative strongly relies not only on its structural variation but also on the Li-involved discharging process, electronic properties, and, most importantly, “solvation energy”. A universal correlation of redox potential with electron affinity and solvation energy addresses that chloranils would experience two-stage transition behaviors during the discharging process, implying a critical role of solvation energy in their cathodic deactivation and thus suggesting a smart approach for the systematic design of high-performance organic cathodes. Electrostatic potential maps unambiguously describe the change in the reductive ability of a chloranil derivative during the Li-involved discharging process.

Despite the potential of incorporating electron-withdrawing cyano functional groups in organic cathode materials for sodium-ion batteries, a systematic understanding of the effect of the functional...

The adsorption of sulfur hexafluoride (SF6) by a transition metal-porphyrin structure embedded on the surface of graphene (MN4-graphene) was evaluated using first-principles density functional theory calculations by constructing the adsorption energy profile. The mutual balance between physisorption and chemisorption was assessed by analyzing the characteristics of the interaction between each central metal atom as an adsorption center and the SF6 molecule. CaN4- and CrN4-graphene had moderate adsorption energies of about -1.5 eV. The results indicate the feasibility of these species as reusable SF6 adsorbents, even under ambient conditions. This study provides deeper insight into the adsorption of SF6 and the potential of transition metal-porphyrin structures as SF6 capture materials for mitigating global warming.

Adsorption of CO2 molecules on amorphous silica surface in the absence/presence of Si–H defects and KCl nanoparticles under various humidity and temperature conditions is investigated using grand-c...

Limited information on organic materials for cathodes in sodium-ion batteries has been addressed as a critical issue to be overcome for designing promising candidates. Herein, we comprehensively in...

Identification of redox-active moieties other than well-known carbonyl is essential to design the best candidates for organic cathodes in lithium-ion batteries among a broad-array of organic materials. In this study, an advanced computational modeling approach is employed to comprehensively investigate the redox properties for two representative organic classes, namely carbonitriles and quinones. It is highlighted that organic molecules with conjugating (non-conjugating) backbones would show higher redox potential for longer (shorter) backbone, owing to the strengthened inductive effect. Further examination verifies the importance of the relative electron-withdrawing strength of functionality over hydrogen on the redox potential and battery performance, suggesting a molecular design direction toward a carbonitrile with a longer conjugating backbone functionalized by an acyl chloride for highly-durable, high-performance cathodes. All these findings are comprehensively understood by the established universal correlations on redox property-electron affinity-solvation energy, highlighting two-stage transition behaviors of carbonitriles during the discharging process.

Flexible and easily-processable materials exhibiting excellent electromagnetic interference (EMI) shielding performance are desirable for EMI shielding applications in electronic devices, which are getting progressively smaller and smarter. This study reports single-walled carbon nanotube (SWCNT)/poly(ethylene-alt-maleic anhydride) (PEMA) composite films with an excellent EMI shielding performance fabricated by a simple bar-coating and doping process. The AuCl3-doped SWCNT/PEMA composite films exhibited an excellent EMI shielding effectiveness (SE) of 96.3 dB at a thickness of 0.031 mm. The EMI SE values of the AuCl3-doped SWCNT/PEMA composite films are higher than any other reported synthetic materials with a similar thickness. The excellent EMI shielding performance is attributed to the high electrical conductivity. The conductivity of the SWCNT/PEMA composite films can be increased effectively to 8500 S cm-1 through the AuCl3-doping process. It was further confirmed by MD simulations that the introduction of only 30 wt.% PEMA polymer is effective for obtaining well-dispersed SWCNTs in the composite films. It is noteworthy that such a small fraction of PEMA polymers is advantageous both for decreasing the volume fraction of the insulating polymers and facilitating the chemisorption of dopants onto the SWCNT surfaces.

Cyclic organic compounds with pentagon rings have been paid less attention for cathodes in lithium-ion batteries as compared with aromatic compounds. In this study, we investigate the Li-binding thermodynamics, redox properties, and theoretical performance for a selected set of heteroatom-containing, pentagon-shaped, organic compounds, namely borole, pyrrole, furan, phosphole, thiophene, and their derivatives to assess their potential for organic cathode materials. This investigation provides us with three important findings. First, the Li-binding thermodynamics and redox properties for the organic compounds would be systematically tailored by the type of the incorporated heteroatom and backbone length, exhibiting both the strongest Li-binding and the highest redox potential for borole. Second, it is highlighted that borole can store up to two Li atoms per molecule exhibiting the exceptionally high charge capacity (839 mA h/g) despite the absence of any well-known redox-active moieties (e.g., carbonyl). Third, dibenzothiophene exhibits weak and comparable Li-binding strengths at multiple feasible binding configurations with an indication of its low Li-storage capability, while the others dominantly bind with Li at their most stable binding configurations. All these findings will provide an insight into the guidelines for the systematic design of promising heterocyclic organic compounds (i.e., borole-based insoluble polymeric forms) for cathodes in secondary batteries.

The metal oxide/graphene hybrid nanomaterials have been known as promising functional materials for advanced applications such as high capacitive electrode material of secondary batteries, and high sensitive material of high performance gas sensors. Here, morphology controlled vanadium dioxide (VO2) nanostructures were grown on Si wafer and exfoliated graphene by the vapor transport method using a horizontal furnace system. One-dimensional VO2 nanowires were grown on SiO2(300 nm)/Si substrate under 0.4 kPa condition. On the other hand, thick polycrystalline of VO2 platelets were grown on exfoliated graphene nanosheets under 0.4 kPa condition. In addition, polycrystalline VO2 platelets were only grown on exfoliated graphene nanosheets under 101 kPa (atmospheric pressure) condition. The growth of polycrystalline VO2 platelets on graphene nanosheets in atmospheric pressure condition is attributed to preferential growth on functional group of graphene surface such as carbonyl. The functional group is served as nucleation site of VO2 nanostructures.

The physical properties of nano-sized metal oxide semiconductors are influenced by the nanostructures as well as the crystallinity, thus the growth of crystalline tin oxide (SnO) with controlled morphologies would be important to its applications. To date, the various morphologies of SnO have been successfully synthesized such as nanodisks, nanobelts, nanoplatelets, nanoslabs, nanoflowers, and nanobranches. Here, the vertical free-standing SnO nanostructures were densely grown on single layer graphene (SLG) by vapor transport method. Compared with the tilted SnO nanostructures on SiO2/Si substrate, surface area ratio of the free-standing SnO nanostructures exhibit over of 4.4 times. According to analysis results such as Raman spectroscopy, FE-SEM, XRD, and FE-TEM, uniform and high quality free-standing SnO nanostructures were grown on large area SLG. We observed that the synthetic shapes of SnO nanostructures are different depending on the presence or absence of graphene film on substrate.

Despite the potential of large organic molecules for insoluble cathode materials in lithium-ion batteries, they have attracted less attention owing to the penalty in the molecular weight. Herein, an advanced computational modeling approach is employed to comprehensively explore the electrochemical characteristics and theoretical charge/energy storage capability for a series of sumanene derivatives. It is highlighted from this investigation that the carbonyl moiety is generally beneficial to the improvement of the redox properties for the sumanenes. The sumanene with hexagon rings fully functionalized by six carbonyls particularly exhibits both the remarkably high redox potential (3.53 V vs Li/Li

In this study, we have developed a protocol for exploring the vast chemical space of possible perovskites and screening promising candidates. Furthermore, we examined the factors that affect the band gap energies of perovskites. The Goldschmidt tolerance factor and octahedral factor, which range from 0.98 to 1 and from 0.45 to 0.7, respectively, are used to filter only highly cubic perovskites that are stable at room temperature. After removing rare or radioactively unstable elements, quantum mechanical density functional theory calculations are performed on the remaining perovskites to assess whether their electronic properties such as band structure are suitable for solar cell applications. Similar calculations are performed on the Ruddlesden-Popper phase. Furthermore, machine learning was utilized to assess the significance of input parameters affecting the band gap of the perovskites.

Understanding thermodynamics and reduction potentials of boron-doped corannulenes (BDCs) can provide meaningful insight to establish strategies for designing doping processes of organic materials applicable to cathodes in lithium-ion batteries (LIBs). In this study, a comprehensive set of BDC models is prepared to investigate the effect of the number and geometric position of doped boron atoms on the thermodynamic stability and redox properties of the corannulene. Our investigation enables us to evaluate their potential as organic cathode materials in LIBs. In this study, it is found that the first and second boron atoms can be exclusively doped in thermodynamically stable positions. Corannulene derivatives doped by the boron atom show enhanced reduction potentials ranged from 2.41 to 5.05 V vs Li/Li+ as compared with the pristine corannulene (0.9 V vs Li/Li+). A higher level of structural heterogeneity created by another boron atom does not guarantee a higher reduction potential (3.03 and 2.51 V vs Li/Li...

We have studied the redox potentials and electronic properties of C 60 and C 59 N using density functional theory method. It is found that doping C 60 with one nitrogen atom results in a slight increase in redox potential. Next, we have also studied C 59 N functionalized with various redox-active oxygen containing functional groups and strongly electron withdrawing functional groups. It is found that the intrinsic electronic structure of the molecule is the major determinant of the redox potential. Our DFT calculations show that the electron affinity to redox potential of functionalized C 59 N is correlated with the LUMO of the systems very well. This is the first systematic study on the redox properties and electronic structures of N-doped C 60 systems.

We performed a computational search for selective NH3 capture of metal–porphyrin-like graphenes using first-principles density functional theory calculations. Using equilibrium thermodynamics param...

In this study, we utilize a density functional theory-machine learning framework to develop a high-throughput screening method for designing new molecular electrode materials. For this purpose, a density functional theory modeling approach is employed to predict basic quantum mechanical quantities such as redox potentials, and electronic properties such as electron affinity, highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), for a selected set of organic materials. Both the electronic properties and structural information, such as the numbers of oxygen atoms, lithium atoms, boron atoms, carbon atoms, hydrogen atoms, and aromatic rings, are considered as input variables for the machine learning-based prediction of redox potentials. The large-set of input variables are further downsized using a linear correlation analysis to have six core input variables, namely electron affinity, HOMO, LUMO, HOMO-LUMO gap, the number of oxygen atoms and the number of lithium atoms. The artificial neural network trained using the quasi-Newton method demonstrates a capability for accurately estimating the redox potentials. From the contribution analysis, in which the influence of each input on the target are accessed, we highlight that the electron affinity has the highest contribution to redox potential, followed by the number of oxygen atoms, HOMO-LUMO gap, the number of lithium atoms, LUMO, and HOMO, in order.

Boron-doped coronenes are attractive as promising positive electrode materials for lithium-ion batteries due to the unique physical and chemical properties of coronene. In this study, we computationally investigate the thermodynamics and redox properties of boron-doped coronenes using the first-principles density functional theory method to evaluate their potential as positive electrodes. It is found from our computations that the redox potentials of the boron-doped coronenes change as a function of the number of doped boron atoms and their distribution, predicting that the weight-averaged redox potentials of one-boron- and two-boron-doped coronenes would reach 5.30 V and 2.23 V, respectively, with respect to Li/Li+. It is highlighted that the highest redox potential of 5.42 V vs. Li/Li+ is predicted for the coronene with a boron atom doped at an edge position. Further investigation on the electronic properties of the boron-doped coronenes provides a strong correlation of the redox potential with the electron affinity, but poor correlation with the lowest unoccupied molecular orbital. Last, a proposed synthetic route that utilizes a pristine coronene reacting with B2O3 and Mg for developing boron-doped-coronenes provides viable thermodynamic conditions of the released CO pressures of ∼1.3 × 10−6 atm at 1073 K and ∼2.8 × 10−5 atm at 1273 K.

Metal-organic frameworks (MOFs) have attracted a special attention to the selective capture of harmful gases from air, owing to the presence of a high density of active surfaces that can be tailored by an appropriate modification. In this paper, recent studies on appropriate approaches for the selective capture of harmful gases (NH3, CO, H2S, NOx, SOx, Cl2, etc.) performed via experimental and computational methods are comprehensively reviewed with the aim of establishing well-designed strategies for the specific tasks. Three primary conclusions regarding the design strategy of MOFs are highlighted from the reviewed studies: the introduction of appropriate open metal sites for the selective capture of polar harmful gases, inefficiency of open metal sites introduced for the selective capture of non-polar harmful gases, and introduction of appropriate surface functionality for individual harmful gas. It is believed that the review will play a critical role in designing promising MOFs with appropriate surface chemistry for the selective capture of harmful gases from air.

A molecular dynamics simulation method was employed to investigate the effects of thermal shrinkage temperatures and comonomers on the thermal shrinkage of a uniaxially stretched PET copolymer model. Our investigation draws three primary conclusions. First, the thermal shrinkage ratio of the PET copolymer would strongly depend on the thermal shrinkage temperature, showing that the thermal shrinkage ratio is proportional to the thermal shrinkage temperature. It is inferred that the thermal shrinkage temperature provides kinetic energy to overcome the activation energy barrier for the molecular relaxation of the stretched polymer chains. Second, the introduction of a bulky comonomer limits the conformational rearrangement of the PET copolymer chain during the uniaxial stretching process owing to the limited chain flexibility. Therefore, it is confirmed that the thermal shrinkage can be tuned as a function of process conditions and comonomer type. Third, our analysis on the PET copolymer film at molecular levels further verifies that the trans–gauche transformation in the polymer backbone is the main factor for the thermal shrinkage of uniaxially stretched PET copolymer systems.

In thermal shrinkage process for polyethylene terephthalate (PET) films, PET film is uniaxially stretched and then thermally relaxed. We investigate the effect of heat relaxation temperature on the thermal shrinkage of uniaxially stretched PET film using molecular dynamics simulation method. Through our investigation, we find that the thermal shrinkage ratio of the amorphous PET film is reduced as a function of heat relaxation temperature, whereas the skirt ratio is weakly correlated with the heat relaxation temperature, exhibiting the most negative skirt ratio in the case of the highest thermal shrinkage ratio. Our analysis on the PET film at molecular level further verifies that the trans-gauche transformation observed in ethylene glycol units during the simulated process is a driving force for the thermal shrinkage of uniaxially stretched PET systems.

Developing styrene (ST) selective adsorbents is an important issue in the petrochemical industry because ST is a crucial precursor for many useful materials. Since ST often presents as mixtures containing ethylbenzene (EB), an effective adsorbent having high ST selectivity over EB, large ST adsorption capacity, and good repeated adsorption/desorption is needed. We hypothesized that Cu(I) ions could provide a special ST selectivity due to unsaturated π-orbitals in ST. We have successfully loaded Cu(I) ions within a mesoporous metal–organic framework (MOF) by using redox-active Fe(II) sites in the MOF. By control experiments for the MOFs with and without Cu(I) ions, we verified for the first time that Cu(I) ions have strong ST selectivity over EB. The Cu(I)-loaded MOF (Cu(M)@MIL-100(Fe)) shows the largest ST uptakes and the highest ST/EB selectivity among the reported values for MOF adsorbents. Additionally, Cu(M)@MIL-100(Fe) maintains its good performance for several cycles. These indicate that Cu(M)@MIL-100(Fe) is a prospective adsorbent for ST/EB separation. We believe this Cu(I) incorporation strategy could open a new way to develop styrene selective adsorbents.

Summary Hydrogen is an alternative clean energy carrier that can replace current fossil fuels for vehicular applications. Thus, it is important to develop a method that would enable a high density of hydrogen to be stored safely under the operating conditions of polymer electrolyte membrane fuel cells. Even though metal hydrides are regarded as promising candidates that can safely store a high density of hydrogen, their stable nature makes it difficult for them to release hydrogen at mild temperatures in the range of 50 to 150°C. In this review, 3 primary strategies, namely, introduction of appropriate dopants, particle size control, and design of novel reactant mixtures based on high-throughput screening methods, are briefly described with the aim of evaluating the potential of metal hydrides for hydrogen storage applications. The review suggests that successful development of promising hydrogen storage systems will depend on collaborative introduction of these 3 primary design strategies through the combined utilization of experimental and computational techniques to overcome the major challenges associated with the reaction thermodynamics of metal hydrides.

Organic materials have attracted considerable attention as potential positive electrodes in lithium-ion batteries owing to their high densities of active surface sites, which can promote fast redox reactions. Rational design strategies for developing redox-active organic materials, however, have not been established systematically. In this work, recent approaches to rational development of organic positive electrodes are comprehensively reviewed to establish design strategies for organic positive electrodes. Three primary conclusions are highlighted: (i) The ability of pristine organic materials to exhibit excellent cell performance is limited. (ii) Incorporation of appropriate functionalities into organic materials can significantly improve their redox activities. (iii) Uniform dispersion of redox-active inorganic materials in a matrix of conductive carbon materials provides nanostructured organic–inorganic composites with optimized cell performance. The strategies outlined in this review will play a cri...

Since adsorption performances are dominantly determined by adsorbate–adsorbent interactions, accurate theoretical prediction of the thermodynamic characteristics of gas adsorption is critical for designing new sorbent materials as well as understanding the adsorption mechanisms. Here, through our molecular modeling approach using a newly developed quantum-mechanics-based force field, it is demonstrated that the CO2 adsorption selectivity of SBA-15 can be enhanced by incorporating crystalline potassium chloride particles. It is noted that the induced intensive electrostatic fields around potassium chloride clusters create gas-trapping sites with high selectivity for CO2 adsorption. The newly developed force field can provide a reliable theoretical tool for accurately evaluating the gas adsorption on given adsorbents, which can be utilized to identify good gas adsorbents.

Self-polymerized dopamine is a versatile coating material that has various oxygen and nitrogen functional groups. Here, we demonstrate the redox-active properties of self-polymerized dopamine on the surface of few-walled carbon nanotubes (FWNTs), which can be used as organic cathode materials for both Li- and Na-ion batteries. We reveal the multiple redox reactions between self-polymerized dopamine and electrolyte ions in the high voltage region from 2.5 to 4.1 V vs. Li using both density functional theory (DFT) calculations and electrochemical measurements. Free-standing and flexible hybrid electrodes are assembled using a vacuum filtration method, which have a 3D porous network structure consisting of polydopamine coated FWNTs. The hybrid electrodes exhibit gravimetric capacities of ∼133 mA h g−1 in Li-cells and ∼109 mA h g−1 in Na-cells utilizing double layer capacitance from FWNTs and multiple redox-reactions from polydopamine. The polydopamine itself within the hybrid film can store high gravimetric capacities of ∼235 mA h g−1 in Li-cells and ∼213 mA h g−1 in Na-cells. In addition, the hybrid electrodes show a high rate-performance and excellent cycling stability, suggesting that self-polymerized dopamine is a promising cathode material for organic rechargeable batteries.

The interface-to-volume ratio of the structure and the transport property of the charge careers are the two main factors affecting the photovoltaic cell performance. In this study, the blends of poly(3-alkylthiophene) (P3AT) (A denotes H, N, and D for hexyl, nonyl, and dodecyl, respectively) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) are investigated to understand the effect of the variation of molecular structure of the thiophene-based polymer in the active layer on the two main factors. First, we develop well-designed coarse-grained models to efficiently describe P3AT-PCBM systems. Next, the coarse-grained molecular dynamics simulations are performed to investigate the structural properties of three coarse-grained active layer systems, P3AT-PCBM. We conclude from our simulated analysis that the P3HT-PCBM system will provide the structurally optimized condition for the best photovoltaic cell performance. This is evidenced by two observations: (1) P3HT exhibits a good contact with PCBM in molecular level and (2) the P3HT-PCBM system forms a well-organized molecular network in each of the electron donor and accepter phases.

Terahertz optical and dielectric properties of AlN ceramics fabricated by hot pressed sintering are investigated by THz time-domain spectroscopy in the frequency range of 0.2–3.5 THz. The measured properties of the pure AlN ceramic are compared with those of Y 2 O 3 -added AlN ceramic. Two prominent resonance modes, which are essentially responsible for the dielectric properties of the Y 2 O 3 -added AlN in terahertz regime, are characterized at ω TO1 / (2 π ) = 2.76 THz (92 cm −1 ) and ω TO2 / (2 π ) = 18.2 THz (605 cm −1 ) and are well described by the pseudo-harmonic oscillator model through theoretical fitting. The resonance ω TO1 at 2.76 THz is proposed to be due to the formation of a YAG (Y 3 Al 5 O 12 ) secondary phase in Y 2 O 3 -added AlN ceramic. From the experimental results, good correlation is observed between the prominent peak of YAG secondary phase at 2.76 THz and thermal conductivity. Additionally, there is a high correlation between densification and refractive index of AlN ceramics fabricated by hot pressed sintering.

Despite the potential of organic cathodes in sodium-ion batteries, their redox properties still need to be explored. In this study, a density functional theory modeling approach is employed to comprehensively investigate the redox properties and theoretical performance parameters for a selected set of fluoranil derivatives as cathode materials. The redox properties are further correlated with various characteristics including structural variations, electronic properties, and solvation. Three primary conclusions are drawn. First, the incorporation of bulky trifluoromethyl functional group(s) into fluoranil increases its redox potential but significantly decreases its gravimetric charge capacity. This suggests that the trifluoromethyl functional group(s) would be detrimental to the design of high-performance batteries. Second, fluoranil exhibits significant enhancements in terms of redox properties and theoretical performance compared with its hydrogenated form, benzoquinone, suggesting a desired strategy for designing high-performance batteries. Third, the redox properties of fluoranil derivatives would strongly rely not only on structural variations (e.g., bulkiness) and electronic properties (e.g., functionality) but also on solvation energy. It is further verified that cathodic deactivation could be completed by solvation energy. The new understanding will provide us with guidelines for an efficient design of promising organic cathode materials.

Carbon monoxide (CO) is an important raw material in chemical industries; however, its separation through solid-state polymer membranes has not been extensively investigated. Herein, a series of comb-like copolymers, i.e., poly(2-hydroxypropyl-2-(methacryloyloxy) ethyl phthalate-co-acrylic acid) (PHMEP-co-PAA), is synthesized and used as a matrix to incorporate AgBF4 and ionic liquid ([bmim][BF4]) for solid-state facilitated CO transport membrane. The carbonyl moeities of the copolymer phthalate and carboxyl groups effectively form a complex with the Ag ions. CO/N2 separation performance is improved by introducing AgBF4 together with [bmim][BF4] into the copolymer matrix, which is supported by spectroscopic analysis and molecular dynamics simulations. Incorporating AgBF4 significantly increases the interaction energy between the membrane and CO molecules, demonstrating that Ag salts act as facilitated CO transport carriers and increase CO solubility in the membrane. Results show that the ionic liquid prevents comb copolymer aggregation and improves CO/N2 selectivity. The PHMEP-co-PAA copolymer monomeric ratio affects the CO/N2 selectivity and carrier stability. Copolymers with high PHMEP content (70 wt%) show the highest CO/N2 selectivity due to strong polymer-CO interaction energies. Performance optimization provided a CO/N2 selectivity of 16.2, one of the highest values reported so far, with a CO permeance of 2.1 GPU. Simultaneous increase in CO permeance and CO/N2 selectivity with carrier loading clearly indicates facilitated CO transport. The simulation analysis effectively interprets the experimental separation performance and can be used for designing CO separation membranes.

Doping capability is primitively governed by the energy level offset between the highest occupied molecular orbital (HOMO) of conjugated polymers (CPs) and the lowest unoccupied molecular orbital (LUMO) of dopants. A poor doping efficiency is obtained when doping directly using NOBF4 forming a large energy offset with the CP, while the devised doping strategy is found to significantly improve the doping efficiency (electrical conductivity) by sequentially treating the NOBF4 to the pre-doped CP with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquino-dimethane (F4TCNQ), establishing a relatively small energy level offset. It is verified that the cascade doping strategy requires receptive sites for each dopant to further improve the doping efficiency, and provides fast reaction kinetics energetically. An outstanding electrical conductivity (>610 S cm-1 ) is achieved through the optimization of the devised doping strategy, and spectroscopy analysis, including Hall effect measurement, supports more efficient charge carrier generation via the devised cascade doping.

Molecular dynamics simulations are performed to investigate the cooperatively catalyzed aldol condensation between acetone and 4-nitrobenzaldehyde on alkylamine (or alkylenamine)-grafted silica surfaces, focusing on the mechanism of the catalytic activation of the acetone and 4-nitrobenzaldehyde by the acidic surface silanols followed by the nucleophilic attack of the basic amine functional group toward the activated reactant. From the analysis of the correlations between the catalytically active acid-base sites and reactants, it is concluded that the catalytic cooperativity of the acid-base pair can be affected by two factors: (1) the competition between the silanol and the amine (or enamine) to form a hydrogen bond with a reactant and (2) the flexibility of the alkylamine (or alkylenamine) backbone. Increasing the flexibility of the alkylamine facilitates the nucleophilic attack of the amine on the reactants. From the molecular dynamics simulations, it is found that C3 propylamine and C4 butylamine linkers exhibit the highest probability of reaction, which is consistent with the experimental observation that the activity of the aldol reaction on mesoporous silica depends on the length of alkylamine grafted on the silica surface. This simulation work serves as a pioneering study demonstrating how the molecular simulation approach can be successfully employed to investigate the cooperative catalytic activity of such bifunctional acid-base catalysts.

While nitrogen and argon isotherms at their respective boiling points are commonly used for the BET analysis of porous materials, CO2 isotherms at 273 K have been suggested as an alternative option for materials containing very small pores in which nitrogen and argon molecules cannot access at cryogenic temperatures. However, it has been known that the BET surface areas obtained from CO2 isotherms are not really meaningful in an absolute sense due to the strong CO2–CO2 interaction. In this study, CO2 isotherms in metal–organic frameworks (MOFs) and zeolites were predicted by grand canonical Monte Carlo (GCMC) simulations and used to evaluate the BET analysis for these materials. For all the microporous materials with varied pore sizes, the BET surface areas calculated from the simulated CO2 isotherms agreed roughly with their geometric surface areas from the crystal structures. Moreover, a clear selection of a proper BET linear region was possible for the material possessing only ultra-micropores. These results indicate that the BET surface areas determined from CO2 isotherms at 273 K may be considered reasonable for adsorbents containing only ultra-micropores where the BET surface areas based on N2 or Ar isotherms at cryogenic temperatures are not available.

Olefin/paraffin separation is an important and challenging issue because the two molecules have similar physicochemical properties. Although a couple of olefin adsorbents have been developed by introducing inorganic nanoparticles into metal-organic frameworks (MOFs), there has been no study on the development of an olefin adsorbent by introducing a certain organic functional group into a MOF. In this study, we posited that azo compounds could offer olefin/paraffin selectivity. We have revealed using first-principles calculations that the simplest aromatic azo compound (azobenzene, Azob) has an unusual propylene/propane selectivity due to special electrostatic interactions between Azob and propylene molecules. On the basis of this interesting discovery, we have synthesized a novel propylene adsorbent, MIL-101(Cr)_DAA, by grafting 4,4'-diaminoazobenzene (DAA) into open metal sites in a mesoporous MIL-101(Cr). Remarkably, MIL-101(Cr)_DAA exhibited enhanced propylene/propane selectivity as well as considerably higher propylene heat of adsorption compared to pristine MIL-101(Cr) while maintaining the high working capacity of MIL-101(Cr). This clearly indicates that azo compounds when introduced into MOFs can provide propylene selectivity. Moreover, MIL-101(Cr)_DAA showed good C3H6/C3H8 separation and easy regeneration performances from packed-bed breakthrough experiments and retained its propylene adsorption capacity even after exposure to air for 12 h. As far as we know, this is the first study that improves the olefin selectivity of MOF by postsynthetically introducing an organic functional group.

A thermodynamic analysis using quantum chemical methods was carried out to identify optimal functional group candidates that can be included in metal–organic frameworks and activated carbons for the selective capture of toxic industrial chemicals (TICs) in humid air. We calculated the binding energies of 14 critical TICs plus water with a series of 10 functional groups attached to a naphthalene ring model. Using vibrational calculations, the free energies of adsorption were calculated in addition to the binding energies. Our results show that, in these systems, the binding energies and free energies follow similar trends. We identified copper(I) carboxylate as the optimal functional group (among those studied) for the selective binding of the majority of the TICs in humid air, and this functional group exhibits especially strong binding for sulfuric acid. Further thermodynamic analysis shows that the presence of water weakens the binding strength of sulfuric acid with the copper carboxylate group. Our calculations predict that functionalization of aromatic rings would be detrimental to selective capture of COCl2, CO2, and Cl2 under humid conditions. Finally, we found that forming an ionic complex, H3O+HSO4−, between H2SO4 and H2O via proton transfer is not favorable on copper carboxylate.

The high electron affinity of fullerene C60 coupled with the rich chemistry of carbon makes it a promising material for cathode applications in lithium-ion batteries. Since boron has one electron less than carbon, the presence of boron on C60 cages is expected to generate electron deficiency in C60 , and thereby to enhance its electron affinity. By using density functional theory (DFT), we studied the redox potentials and electronic properties of C60 and C59 B. We have found that doping C60 with one boron atom results in a substantial increase in redox potential from 2.462 V to 3.709 V, which was attributed to the formation of an open shell system. We also investigated the redox and electronic properties of C59 B functionalized with various redox-active oxygen containing functional groups (OCFGs). For the combination of functionalization with OCFGs and boron doping, it is found that the enhancement of redox potential is reduced, which is mainly attributed to the open shell structure being changed to a closed-shell one. Nevertheless, the redox potentials are still higher than that of pristine C60 . From the observation that the lowest unoccupied molecular orbital of closed-shell OCFG- functionalized C59 B is correlated well with the redox potential, it was confirmed that the spin state is crucial to be considered to understand the relationship between electronic structure and redox properties.

We present a 7nm technology with the tightest contacted poly pitch (CPP) of 44/48nm and metallization pitch of 36nm ever reported in FinFET technology. To overcome optical lithography limits, Extreme Ultraviolet Lithography (EUV) has been introduced for multiple critical levels for the first time. Dual strained channels have been also implemented to enhance mobility for high performance applications.

The thermodynamic and electrochemical redox properties for a set of ketone derivatives of phenalenyl and anthracene have been investigated to assess their potential application for positive electrode materials in rechargeable lithium-ion batteries. Using first-principles DFT, it was found that 1) the thermodynamic stabilities of ketone derivatives are strongly dependent on the distribution of the carbonyl groups and 2) the redox potential is increased when increasing the number of the incorporated carbonyl groups. The highest values are 3.93 V versus Li/Li+ for the phenalenyl derivatives and 3.82 V versus Li/Li+ for the anthracene derivatives. It is further highlighted that the redox potential of an organic molecule is also strongly correlated with its spin state in the thermodynamically stable form.

We report the synthesis of a series of alcohol-soluble comb copolymers, specifically poly(oxyethylene methacrylate)-co-poly(2-(4-benzoyl-3-hydroxy phenoxy) ethyl acrylate) (POM-PBHP), with various compositions, as well as their use in CO2 capture membranes. The POM-PBHP comb copolymers were synthesized through a low-cost free-radical polymerization method and analyzed based on Fourier transform infrared spectroscopy and nuclear magnetic resonance. The interactions and structures of the comb copolymers were characterized via X-ray diffraction, differential scanning calorimetry, and thermogravimetric analysis. The comb copolymers showed good solubility in volatile nontoxic ethanol, allowing them to be coated onto microporous polymer supports to form thin-film composite membranes. While both neat POM and PBHP membranes showed very poor separation properties, the POM-PBHP comb copolymers were effective at separating CO2 from N2. This is because the POM chains with ether oxygen groups have a strong affinity for CO2, leading to high CO2 permeance, whereas the rigid PBHP chains with aromatic rings hinder N2 permeance based on reduced chain mobility. All the full-atomistic molecular dynamics simulations based on density functional theory were also used to characterize the molecular structure and binding energy for CO2, which is consistent with the experimental results. The performance of the membranes was greatest when the content of PBHP in the copolymer was 15 wt%. The CO2/N2 selectivity and CO2 permeability reached 46.6 and 111 Barrer, respectively, which represents one of the highest values for alcohol-soluble, additive-free polymeric membranes and is similar to that of commercial PEBAX membrane.

Understanding the thermodynamic stability and redox properties of oxygen functional groups on graphene is critical to systematically design stable graphene-based positive electrode materials with high potential for lithium-ion battery applications. In this work, we study the thermodynamic and redox properties of graphene functionalized with carbonyl and hydroxyl groups, and the evolution of these properties with the number, types and distribution of functional groups by employing the density functional theory method. It is found that the redox potential of the functionalized graphene is sensitive to the types, number, and distribution of oxygen functional groups. First, the carbonyl group induces higher redox potential than the hydroxyl group. Second, more carbonyl groups would result in higher redox potential. Lastly, the locally concentrated distribution of the carbonyl group is more beneficial to have higher redox potential compared to the uniformly dispersed distribution. In contrast, the distribution of the hydroxyl group does not affect the redox potential significantly. Thermodynamic investigation demonstrates that the incorporation of carbonyl groups at the edge of graphene is a promising strategy for designing thermodynamically stable positive electrode materials with high redox potentials.

The Li-binding thermodynamics and redox potentials of seven different quinone derivatives are investigated to determine their suitability as positive electrode materials for lithium-ion batteries. First, using density functional theory (DFT) calculations on the interactions between the quinone derivatives and Li atoms, we find that the Li atoms primarily bind with the carbonyl groups in the test molecules. Next, we observed that the redox properties of the quinone derivatives can be tuned in the desired direction by systematically modifying their chemical structures using electron-withdrawing functional groups. Further, DFT-based investigations of the redox potentials of the Li-bound quinone derivatives provide insights regarding the changes induced in their redox properties during the discharging process. The redox potential decreases as the number of bound Li atoms is increased. However, we found that the functionalization of the quinone derivatives with carboxylic acids can improve their redox potential as well as their charge capacity. Through this study, we also determined that the cathodic activity of quinone derivatives during the discharging process relies strongly on the solvation effect as well as on the number of carbonyl groups available for further Li binding.

Graphene has been received a considerable amount of attention as a transparent conducting electrode (TCE) which may be able to replace indium tin oxide (ITO) to overcome the significant weakness of the poor flexibility of ITO. Given that graphene is the thinnest 2-dimensional (2D) material known, it shows extremely high flexibility, and its lateral periodic honeycomb structure of sp2-bonded carbon atoms enables ~2.3% of incident light absorption per layer. However, there is a trade-off between the electrical resistance and the optical transmittance, and the fixed absorption rate in graphene limits is use when fabricating devices. Therefore, a more efficient method which continuously controls the optical and electrical properties of graphene is needed. Here, we introduce a method which controls the optical transmittance and the electrical resistance of graphene through various thicknesses of the top Cu layers with a Cu/Ni metal catalyst structure used to fabricate a planar mesh pattern of single and multi-layer graphene. We exhibit a continuous transmittance change from 85% (MLG) to 97.6% (SLG) at an incident light wavelength of 550 nm on graphene samples simultaneously grown in a CVD quartz tube. We also investigate the relationships between the sheet resistances.

A combination of in situ synchrotron powder diffraction energy minimization (DFT) and Raman and infrared spectroscopy confirmed porous interpenetrated 3D framework structures of recently discovered alkali metalminus;zinc borohydrides AZn2(BH4)5 (A = Li Na). In the less zinc rich NaZn(BH4)3 the 3D framework structural model has been confirmed but with a slightly modified description giving an isolated triangular anion [Zn(BH4)3]minus; rather than a 1D anionic chain {[Zn(BH4)3]n}nminus;. Another polymorph of NaZn(BH4)3 isostructural to a new compound LiZn(BH4)3 is proposed by energy minimization. Both compounds the new NaZn(BH4)3 polymorph and LiZn(BH4)3 are however not observed experimentally at ambient pressure and in the temperature range of 100minus;400 K. The alkali metalminus;zinc borohydride NaZn(BH4)3 containing the triangular anion [Zn(BH4)3]minus; is an equivalent of recently characterized alkali metalminus;scandium borohydrides NaSc(BH4)4 and LiSc(BH4)4 based on the tetrahedral [Sc(BH4)4]minus; complex anion.

Several new studies of Mg(BH 4 ) 2 are reported. A 1:1 LiBH 4 :Mg(BH 4 ) 2 mixture was studied by in situ synchrotron X-ray diffraction and reveals an eutectic behavior with the eutectic composition more rich in Mg(BH 4 ) 2 , and the eutectic temperature lower than 456 K. No dual cation compound was observed in this experiment. New vibrational spectra including INS data have been obtained and are compared with theoretical DFT calculations and recent NMR studies, showing good agreement.