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Pidotimod is a chiral drug that possesses two chiral centers, resulting in three isomeric impurities (analytes, A). This study employs electrospray ionization ion trap mass spectrometry (ESI‐MS) through collision‐induced dissociation (CID) to investigate the chiral recognition of pidotimod and its three isomers to eliminate chromatographic separation. Three approaches were explored: (1) Protonated molecules in CID exhibited discriminative potential for diastereomers, with the ability to distinguish between S,S and R,R configurations, albeit with an Rchiral value of ~1.8. However, differentiation between R,S and S,R configurations was not achievable. (2) Alkali adductions (lithium and sodium) only discerned diastereomers. The Rchiral values of the diastereomers obtained from alkali adduct ions were significantly lower than those obtained from protonated ions. (3) Therefore, a third approach was used to address the challenge of distinguishing between R,S and S,R configurations, including the introduction of chiral references (ref) and transition metals (MII) to form metal‐bound complexes [MII(A)(ref)‐H]+. Additionally, we synthesized a novel ligand, 4‐(N‐tert‐butoxycarbonyl [Boc]‐L‐prolinamido)phenol (denoted as ligand A), by modifying N‐t‐Boc‐L‐Pro with 2‐aminophenol, which, in combination with CuII and NiII, enabled simultaneous differentiation of all four isomers. CuII complexes exhibited significant chiral selectivity between R,S and S,R configurations. Density functional theory calculations were performed to further elucidate the stereodynamic behavior and stoichiometry of these ions in the gas phase. These calculations revealed the interaction energy and coordination sites of the precursor ions in the gas phase, correlating well with MS/MS experiment results. Additionally, the logarithm of the CuII complexes' characteristic fragment ion abundance ratio demonstrated a strong linear relationship with enantiomeric excess (ee). This study presents a novel strategy for chiral drug quality control that eliminates chromatographic separation. [ABSTRACT FROM AUTHOR]

Zinc‐based aqueous batteries (ZABs) are attracting extensive attention due to the low cost, high capacity, and environmental benignity of the zinc anode. However, their application is still hindered by the undesired zinc dendrites. Despite Zn‐surface modification being promising in relieving dendrites, a thick separator (i.e. glass fiber, 250–700 μm) is still required to resist the dendrite puncture, which limits volumetric energy density of battery. Here, we pivot from the traditional interphase plus extra separator categories, proposing an all‐in‐one ligand buffer layer (ca. 20 μm) to effectively modulate the Zn2+ transfer and deposition behaviors proved by in situ electrochemical digital holography. Experimental characterizations and density functional theory simulations further reveal that the catechol groups in the buffer layer can accelerate the Zn2+ reduction reaction (ZRR) through the electron‐donating p‐π conjugation effect, decreasing the negative charge in the coordination environment. Without extra separators, the elaborated system endows low polarization below 28.2 mV, long lifespan of 4950 h at 5 mA cm−2 in symmetric batteries, and an unprecedented volumetric energy density of 99.2 Wh L−1 based on the whole pouch cells. The concomitantly "separator‐free" and "dendrite‐free" conjugation effect with an accelerated ZRR process could foster the progression of metallic anodes and benefit energetic aqueous batteries. [ABSTRACT FROM AUTHOR]

Piezochromic materials that exhibit pressure‐dependent luminescence variations are attracting interest with wide potential applications in mechanical sensors, anticounterfeiting and storage devices. Crystalline porous materials (CPMs) have been widely studied in piezochromism for highly tunable luminescence. Nevertheless, reversible and high‐contrast emission response with a wide pressure range is still challenging. Herein, the first example of hierarchical porous cage‐based πOF (Cage‐πOF‐1) with spring structure was synthesized by using aromatic chiral cages as building blocks. Its elastic properties evaluated based on the bulk modulus (9.5 GPa) is softer than most reported CPMs and the collapse point (20.0 GPa) significantly exceeds ever reported CPMs. As smart materials, Cage‐πOF‐1 displays linear pressure‐dependent emission and achieves a high‐contrast emission difference up to 154 nm. Pressure‐responsive limit is up to 16 GPa, outperforming the CPMs reported so far. Dedicated experiments and density functional theory (DFT) calculations illustrate that π–π interactions‐dominated controllable structural shrinkage and porous‐spring‐structure‐mediated elasticity is responsible for the outstanding piezofluorochromism. [ABSTRACT FROM AUTHOR]

The use of mass spectrometry for chiral recognition and quantification has attracted great interest owing to its speed, sensitivity, specificity, and tolerance. However, searching for chiral selectors in chiral analyses using mass spectrometry is still problematic. In this study, chiral drugs could be applied as references for the chiral recognition and enantiomeric quantification of valsartan and voriconazole. Two novel pairs of metal‐bound diastereomeric complex ions were detected by mass spectrometry, namely, nickel (II)‐bound dimeric ions [NiII (2R,5S‐emtricitabine) (S‐valsartan)‐H]+ and [NiII (2R,5S‐emtricitabine) (R‐valsartan)‐H]+ and copper (II)‐bound dimeric ions [CuII (S,S,S‐enalaprilat) (2S,3R‐voriconazole)‐H]+ and [CuII (S,S,S‐enalaprilat) (2R,3S‐voriconazole)‐H]+. The resulting diastereomers were successfully identified based on the relative intensities of their characteristic fragments using tandem mass spectrometry. The logarithm of the characteristic fragment ion abundance ratio exhibited a good linear relationship with the enantiomeric excess. Density functional theory calculations were also performed to elucidate the mechanism of the structural differences observed in the MS results. This established approach proves that chiral drugs can serve as ligands for the rapid recognition and quantitative analysis of other chiral drugs without a chiral chromatographic column or complex sample pretreatment. [ABSTRACT FROM AUTHOR]

Garnet Li7La3Zr2O12 (LLZO) is regarded as a promising solid electrolyte due to its high Li+ conductivity and excellent chemical stability, but suffers from grain boundary resistance and porous structure which restrict its practical applications in lithium–metal batteries. Herein, a novel and highly efficient TiO2‐induced conversion strategy is proposed to generate Li ion‐conductive Li0.5La0.5TiO3, which can simultaneously eliminate the pre‐existing pores/voids and contamination Li2CO3. The Li/LLZTO‐5TiO2/Li symmetric cell exhibits a high critical current density of 1.1 mA cm−2 at 25°C, and the long‐term lithium cycling stability of over 1500 h at 0.1 mA cm−2. More importantly, the excellent performance of LLZTO‐5TiO2 electrolyte is verified by LiCoO2/LiFePO4 coupled full cells. For example, The LiCoO2 coupled full cell exhibits a significant discharge rate capacity of 108 mAh g−1 at 0.1 C, and a discharge capacity retention rate of 91.23% even after 150 cycles of charge and discharge. COMSOL Multiphysics and density functional theory calculation reveal that LLZTO‐5TiO2 electrolyte has a strong lithium affinity and uniform Li ions distribution, which can improve the cycle stability of Li–metal batteries by preventing dendrite growth. [ABSTRACT FROM AUTHOR]

Single‐atom (SA) cocatalysis has obvious superiority in promoting solar‐to‐chemical energy conversion. However, easy aggregation of SAs is very unfavorable to its catalysis for high surface energy. Herein, a photoreduction procedure is adopted to immobilize Ni SAs on CdS nanoparticles (NPs) to construct the synergistic electric metal–semiconductor interaction (EMSI) for highly promoting the simulated sunlight‐driven H2O‐to‐H2 (HTH) conversion in alkaline condition (pH = 14.0) without any sacrificial agent addition, and the nanocatalyst with 1.25‰ of Ni carrying capacity (CdS–Ni1.25‰) achieves the highest HTH conversion rate (8149.71 μmol h−1 g−1, 13.0‐fold greater of that of CdS NPs) and stable photostability accompanied by 27.60% of apparent quantum yield (AQY400 nm). Characterizations and density functional theory calculations indicate that the EMSI on CdS–Ni1.25‰ nanocatalyst greatly improves the light absorption capacity and promotes the orderly bulk‐to‐surface migration of photoexcitons, effectively suppressing their recombination kinetics for higher photoexciton utilization efficiency. Under alkaline conditions, high concentration of OH− ions is easy to react with photogenerated holes to generate hydroxyl radicals for effectively inhibiting the oxidation half‐reaction and obtaining higher HTH conversion performance due to significantly reduced energy barriers on atomic Ni sites. This study provides an insight for improving the performance of a conventional photocatalyst through non‐noble metallic SAs cocatalysis. [ABSTRACT FROM AUTHOR]

Carbon‐supported Au (Au/AC) has been proven to be one of the most promising catalysts in the field of acetylene hydrochlorination. However, the catalytic performance of conventional Au/AC catalyst is usually limited due to the unsatisfactory dispersion of active Au cation on the surface of the support, carbon deposition, and inevitable reduction to inactive Au nanoparticles. Herein, Au catalysts with highly dispersed Au cation were developed using the complexation of dicarbonyl ligand N‐chlorosuccinimide (NCS) and N‐methylsuccinimide (NMS). The obtained Au−NMS/AC and Au−NCS/AC catalysts with 0.1 wt.% Au loading possessed acetylene conversion of 98 % and 88 % at 180 °C and GHSV (C2H2) of 160 h−1, which were clearly better than that of pristine Au/AC. The characterization results showed that coordination between Au cation and ligands enhanced the dispersion of Au species, suppressed the reduction of Au cation, and reduced the formation of carbon deposits. Density functional theory (DFT) calculations suggest that Au−NMS/AC and Au−NCS/AC catalysts follow a HCl‐preferred concerted addition reaction mechanism with lower reaction energy barrier. This favors the high activity and nuclearity stability of the Au center. This study provides great potential for the use of dicarbonyl ligands on Au‐based catalysts in acetylene hydrochlorination. [ABSTRACT FROM AUTHOR]

Carbonaceous materials are considered strong candidates as anode materials for sodium‐ion batteries (SIBs), which are expected to play an indispensable role in the carbon‐neutral era. Herein, novel braided porous carbon fibres (BPCFs) are prepared using the chemical vapour deposition (CVD) method. The BPCFs possess interwoven porous structures and abundant vacancies. The growth mechanism of the BPCFs can be attributed to the polycrystalline transformation of the nanoporous copper catalyst in the early stage of CVD process. Density functional theory calculations suggest that the Na+ adsorption energies of the mono‐vacancy edges of the BPCFs (−1.22 and −1.09 eV) are lower than that of an ideal graphene layer (−0.68 eV), clarifying in detail the adsorption‐dominated sodium storage mechanism. Hence, the BPCFs as an anode material present an outstanding discharge capacity of 401 mAh g−1 at 0.1 A g−1 after 500 cycles. Remarkably, this BPCFs anode, under high‐mass‐loading of 5 mg cm−2, shows excellent long‐term cycling ability with a reversible capacity of 201 mAh g−1 at 10 A g−1 over 1000 cycles. This study provided a novel strategy for the development of high‐performance carbonaceous materials for SIBs. [ABSTRACT FROM AUTHOR]

Low‐dimensional ultrawide bandgap semiconductors demonstrate great potential in fabricating solar‐blind ultraviolet photodetectors. However, the widespread use of detectors is still limited by the low responsivity, large noise, and dark current, and especially few detectors can fulfill the solar‐blind ultraviolet detection and the polarization dependence simultaneously. Herein, a polarization sensitive solar‐blind ultraviolet photodetector based on ultrathin KNb3O8 nanobelts synthesized via chemical vapor deposition growth, is reported. By selecting suitable substrate and tuning the growth temperature, the nonlayered KNb3O8 crystal is grown into the quasi‐1D ultrathin nanobelt with thickness in the range of 4.8–120 nm. Density functional theory calculations and experimental results indicate that the ultrathin KNb3O8 nanobelt possesses an ultrawide bandgap (4.15 eV) as well as unusual in‐plane structural anisotropy. Benefiting from the above features, the ultrathin KNb3O8 nanobelt‐based device exhibits superior photodetection performances with high responsivity (30 A W−1), high detectivity (5.95 × 1011 Jones), and ultralow dark current (7.1 × 10−15 A) in the solar‐blind ultraviolet region (230–280 nm). In addition, the KNb3O8 photodetector displays strong polarization sensitive photoresponse with a linear dichroic ratio of 1.62 at 254 nm. With these remarkable features, the ultrathin KNb3O8 nanobelt provides great opportunities for designing the next‐generation multifunctional solar‐blind ultraviolet optoelectronic devices. [ABSTRACT FROM AUTHOR]

The active site of the industrial Cu/ZnO/Al2O3 catalyst used in CO2 hydrogenation to methanol has been debated for decades. Grand challenges remain in the characterization of structure, composition, and chemical state, both microscopically and spectroscopically, and complete theoretical calculations are limited when it comes to describing the intrinsic activity of the catalyst over the diverse range of structures that emerge under realistic conditions. Here a series of inverse model catalysts of ZnO on copper hydroxide were prepared where the size of ZnO was precisely tuned from atomically dispersed species to nanoparticles using atomic layer deposition. ZnO decoration boosted methanol formation to a rate of 877 gMeOH kgcat−1 h−1 with ≈80 % selectivity at 493 K. High pressure in situ X‐ray absorption spectroscopy demonstrated that the atomically dispersed ZnO species are prone to aggregate at oxygen‐deficient ZnO ensembles instead of forming CuZn metal alloys. By modeling various potential active structures, density functional theory calculations and microkinetic simulations revealed that ZnO/Cu interfaces with oxygen vacancies, rather than stoichiometric interfaces, Cu and CuZn alloys were essential to catalytic activation. [ABSTRACT FROM AUTHOR]

The active site of the industrial Cu/ZnO/Al2O3 catalyst used in CO2 hydrogenation to methanol has been debated for decades. Grand challenges remain in the characterization of structure, composition, and chemical state, both microscopically and spectroscopically, and complete theoretical calculations are limited when it comes to describing the intrinsic activity of the catalyst over the diverse range of structures that emerge under realistic conditions. Here a series of inverse model catalysts of ZnO on copper hydroxide were prepared where the size of ZnO was precisely tuned from atomically dispersed species to nanoparticles using atomic layer deposition. ZnO decoration boosted methanol formation to a rate of 877 gMeOH kgcat−1 h−1 with ≈80 % selectivity at 493 K. High pressure in situ X‐ray absorption spectroscopy demonstrated that the atomically dispersed ZnO species are prone to aggregate at oxygen‐deficient ZnO ensembles instead of forming CuZn metal alloys. By modeling various potential active structures, density functional theory calculations and microkinetic simulations revealed that ZnO/Cu interfaces with oxygen vacancies, rather than stoichiometric interfaces, Cu and CuZn alloys were essential to catalytic activation. [ABSTRACT FROM AUTHOR]

Acetylene hydrochlorination reaction requires toxic mercuric chloride catalyst, which caused serious environmental pollution by mercury in recent years. Though Au‐based catalysts show the best catalytic activity and high rates of acetylene conversion, much work still needs to be done to reduce the cost before their large‐scale applications. Here, a pure pyridine‐based organic polymer was successfully designed and assembled, which contains only one nitrogen species and exhibits a high activity with acetylene conversion reaching 88% and the selectivity of vinyl chloride above 99%. Both experimental and density functional theory (DFT) studies directly demonstrate that the pyridinic N atom in pyridine ring is the active site of the catalyst and the insertion of acetylene to HCl might be the rate‐determining step. Different from traditional carbonization and aminating treatment at high temperature, the pyridine‐based polymers were obtained by polymerization in liquid phase. Besides, the activity of the catalyst may be determined by these combined effects of surface area, pores structure, and the amount of pyridinic N. [ABSTRACT FROM AUTHOR]

The Ni‐B complex 1BCF with a facilely accessible monophosphine (PtBu3) unit was theoretically designed, which was found to be more active than that with an ambiphilic ligand for hydrogenation of styrene. Substituting PtBu3 with a stronger electron donating ligand N‐heterocyclic carbene largely improves the activity of the Ni‐B complex. [ABSTRACT FROM AUTHOR]

Ammonia is an important feedstock for producing fertilizer and chemicals as well as is also a potential energy carrier. Generally, MgO is considered as an electronic promoter for Ru catalysts in ammonia synthesis. In this research, it was found for the first time that surface atoms of Ru particles are stabilized by MgO modification at high temperature and reaction atmosphere, which contained more highly active B5‐sites for ammonia synthesis. Ex situ HRTEM images show similar Ru nanoparticles containing steps with or without promoters. Under reaction temperatures and gas environment, in situ environmental transmission electron microscopy (ETEM) observe that Ru particles without MgO promoter suffer from dynamic change and lost the B5‐sites on Ru steps, which results in the poor ammonia yield obtained by both the continuing‐flow reaction system. While MgO modification can stabilize the Ru surface structure and keep B5‐sites there, which contributes to the much higher ammonia yield. Density functional theory calculations show that B5‐site is a catalytic active center for ammonia synthesis and the N2 dissociation barrier on B5‐site containing step is lower than B5‐site‐free step on Ru nanoparticles. The finding provides a new explanation for the high activity of MgO modified Ru catalysts. Moreover, adding CsOx with MgO will contribute electron donation to stabilized Ru surface and accelerate the ammonia synthesis with five‐fold higher than MgO−Ru/MS at 500 °C. A better fundamental understanding of the dynamics of Ru catalysts and its reaction mechanism in this research is vital for optimizing the design of catalysts for ammonia synthesis. [ABSTRACT FROM AUTHOR]

Searching for energetic materials that balance detonation performance with sensitivity is an enduring ambition in the evolution of high‐energy density materials (HEDMs). The coplanar molecular structures of energetic compounds have a powerful impact on performance. Novel compounds of bis(nitrotriazoles) tetrazine (BNTT) were designed and investigated by density functional theory methods. The coplanar BNTT's oxides were a highlight in molecules with superior performance and acceptable sensitivities. Results showed that all these designed compounds possess high densities, positive heats of formation, remarkable detonation performance, and acceptable impact sensitivity. In particular, B1‐3 possessed higher density (ρ = 1.97 g cm−3) and exhibited good balance between detonation performance (Q = 1779.83 cal g−1, D = 9.48 km s−1, P = 42.01 GPa) and sensitivity (h50% = 28 cm) than trinitroperhydro‐1,3,5‐triazine (RDX). The theoretical study demonstrated that all designed compounds possess acceptable sensitivity. They were seen as the potential candidates of HEDMs. [ABSTRACT FROM AUTHOR]

Introduction of a heterocyclic ring and an amino‐ethyl‐amino group to donor‐acceptor (D‐A) type photosensitive dyes can modulate the lifetime of the charge separation generated in the D‐A dyes as well as their electronic and UV‐vis absorption properties. Here we perform density functional theory (DFT) and time‐dependent density functional theory (TD‐DFT) calculations to study 11 derivatives of a triphenylamine‐pyrimidine, namely MTPA‐Pyc, in order to improve the performance of MTPA‐Pyc as solar cell sensitizers. Five heterocyclic rings and an amino‐ethyl‐amino group were introduced on the styryl moiety of MTPA‐Pyc. The results show that the introduction of heterocyclic rings generally causes an absorption red shift, but the absorption intensity reduces as a result of the increase in the dihedral angle between the donor and acceptor. Further, introduction of an amino‐ethyl‐amino group to these dyes with a heterocyclic ring modification disrupts the conjugation between the donor and acceptor, which does not benefit the absorption but may have the potential to increase the lifetime of charge separation of the dyes. We identify 2 out of 11 dyes that have the best potential for solar cell applications. [ABSTRACT FROM AUTHOR]

It is vital to understand the oxygen reduction reaction (ORR) mechanism at the molecular level for the rational design and synthesis of high activity fuel‐cell catalysts. Surface enhanced Raman spectroscopy (SERS) is a powerful technique capable of detecting the bond vibrations of surface species in the low wavenumber range, however, using it to probe practical nanocatalysts remains extremely challenging. Herein, shell‐isolated nanoparticle‐enhanced Raman spectroscopy (SHINERS) was used to investigate ORR processes on the surface of bimetallic Pt3Co nanocatalyst structures. Direct spectroscopic evidence of *OOH suggests that ORR undergoes an associative mechanism on Pt3Co in both acidic and basic environments. Density functional theory (DFT) calculations show that the weak *O adsorption arise from electronic effect on the Pt3Co surface accounts for enhanced ORR activity. This work shows SHINERS is a promising technique for the real‐time observation of catalytic processes. [ABSTRACT FROM AUTHOR]

Site activity and density are two key factors in determining the overall activity of catalysts in heterogeneous catalysis. Combined DFT calculation, Wulff construction and micro‐kinetic analysis, we reveal here a significant interplay between site activity and density of bcc iron catalyzed ammonia synthesis at low coverage regime. It is found that for large size particles, Fe (111) and (311) surfaces that consist of active C7 sites are limited by their low site density, whereas those with the most abundant sites are limited by their low activity. In contrast, Fe (221), (211) and (310) surfaces which consist of active C7 and/or B5 sites and remain abundant, dominate the overall reaction rate, turn‐over‐frequency and mass specific activity. Turn‐over‐frequency of the smaller Fe particles (2–6 nm) decreases by a factor of two or three due to the absence of (221) surface. For the particle size less than 2 nm, the corresponding activity decreases dramatically owing to the absence of all active C7 and/or B5 sites. Interplay of site abundance and intrinsic activity of catalysts is highlighted, and the insights revealed could be used to design and develop better catalysts for ammonia synthesis and other important reactions of technological interest. Give me the 221! Fe (221), (211) and (310) surfaces which consist of C7 and/or B5 sites and remain abundant, dominate the overall reactivity of the particles larger than 6 nm. The absence of (221) surface at the particle size of 2–6 nm lowers the corresponding TOF. With particle size below 2 nm, the TOF dramatically decreases because of no C7 and B5 sites exposed. [ABSTRACT FROM AUTHOR]

Highly selective hydrogen peroxide (H2O2) synthesis directly from H2 and O2 is a strongly desired reaction for green processes. Herein a highly efficient palladium-tellurium (Pd-Te/TiO2) catalyst with a selectivity of nearly 100 % toward H2O2 under mild conditions (283 K, 0.1 MPa, and a semi-batch continuous flow reactor) is reported. The size of Pd particles was remarkably reduced from 2.1 nm to 1.4 nm with the addition of Te. The Te-modified Pd surface could significantly weaken the dissociative activation of O2, leading to the non-dissociative hydrogenation of O2. Density functional theory calculations illuminated the critical role of Te in the selective hydrogenation of O2, in that the active sites composed of Pd and Te could significantly restrain side reactions. This work has made significant progress on the development of high-selectivity catalysts for the direct synthesis of H2O2 at ambient pressure. [ABSTRACT FROM AUTHOR]

Cobalt-based nanomaterials have been intensively explored as promising noble-metal-free oxygen evolution reaction (OER) electrocatalysts. Herein, we report phase-selective syntheses of novel hierarchical CoTe2 and CoTe nanofleeces for efficient OER catalysts. The CoTe2 nanofleeces exhibited excellent electrocatalytic activity and stablity for OER in alkaline media. The CoTe2 catalyst exhibited superior OER activity compared to the CoTe catalyst, which is comparable to the state-of-the-art RuO2 catalyst. Density functional theory calculations showed that the binding strength and lateral interaction of the reaction intermediates on CoTe2 and CoTe are essential for determining the overpotential required under different conditions. This study provides valuable insights for the rational design of noble-metal-free OER catalysts with high performance and low cost by use of Co-based chalcogenides. [ABSTRACT FROM AUTHOR]

Density functional theory ( DFT) is a powerful tool to study heterogeneous catalysis nowadays. In past decades, numerous DFT calculations have been conducted to investigate the mechanism of catalytic reaction from which the rationale of catalyst design can be revealed. Because the catalyst electronic and geometric structures determine the intrinsic activity, corresponding composition, size, and morphology have been explored extensively to tune the structure-activity relationship for higher activity and selectivity. In this review, we focus on the recent theoretical progress of the crystal phase effect on catalysis. Catalysts with different crystal phases have different symmetries, and could expose very different facets with distinct electronic and geometrical properties, which would have significant influential on the activity and selectivity of the active sites as well as the site density. Exploration of the dependence of catalysis on the crystal phases provides a new rationale of catalysts design toward a high-specific activity. WIREs Comput Mol Sci 2016, 6:571-583. doi: 10.1002/wcms.1267 For further resources related to this article, please visit the . [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) investigations revealed that 4-cyanopyridine was capable of homolytically cleaving the B−B σ bond of diborane via the cooperative coordination to the two boron atoms of the diborane to generate pyridine boryl radicals. Our experimental verification provides supportive evidence for this new B−B activation mode. With this novel activation strategy, we have experimentally realized the catalytic reduction of azo-compounds to hydrazine derivatives, deoxygenation of sulfoxides to sulfides, and reduction of quinones with B2(pin)2 at mild conditions. [ABSTRACT FROM AUTHOR]

The metalation behaviors of 5,15-diphenylporphyrin (2H-DPP) on Pd(111) and Cu/Pd(111) have been investigated using scanning tunneling microscopy and density functional calculations. We show that 2H-DPP molecules deposited on Pd(111) surface form Pd-DPP with a proportion of about 75% already at room temperature (RT). This is in contrast to non-metalation adsorption of 2H-DPP on Cu-Pd alloy at RT. Annealing to 323 K facilitates the metalation of 2H-DPP on Cu-Pd alloy island. The comparison of the results indicates that the metalation of 2H-DPP calls for both enough surface free energy of approaching NH bond and enough reactivity of breaking NH bond. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A low scaling quantum chemistry program, called LSQC, is described in this article. This version includes two linear scaling methods, generalized energy-based fragmentation (GEBF) approach and cluster-in-molecule (CIM) approach. In the GEBF approach, a variety of electron structure methods (including ab initio and density functional theory) are available for the calculations of ground-state energies, geometry optimizations, vibrational spectra, and other molecular properties for large systems. In the CIM approach, the electron correlation energies of large systems can be approximately obtained at the second-order Møller−Plesset perturbation theory and couple cluster levels. In this article, the details and the capabilities of the LSQC program are presented. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Here, we present a simulation study of temperature‐dependent electronic transitions in BiVO3 (BVO) and BiNbO3 (BNO) using density functional theory (DFT) together with generalized gradient approximation (GGA) and two‐dimensional correlation analysis (2D‐CA). The results indicate that heat accumulation can accelerate the degeneracy of V‐3d orbital in BVO and the splitting of Nb‐4d orbital in BNO at 750 K. We found changes in the type of d–p hybrid orbital as follows, for BVO: V‐dx2+y2 + dZ2‐O‐2pz → V‐dx2+y2‐O‐2pz; and for BNO: Nb‐dx2+y2‐O‐2pz → Nb‐dx2+y2 + dZ2‐O‐2pz. Furthermore, we found changes in the type of hybrid orbital leading to the following electron–electron interactions, for BVO: t2g (V‐dZ2‐O‐2pz) + eg (V‐dx2+y2‐O‐2pz) → t2g (V‐dx2+y2‐O‐2pz); and for BNO: t2g + eg (Nb‐dx2+y2 + dZ2‐O‐2pz) → t2g (Nb‐dx2+y2‐O‐2pz) + eg (Nb‐dz2‐O‐2pz). The electronic transitions are determined by a charge‐transfer from the occupied O‐2p4 orbitals to the unoccupied V‐3d3 (or Nb‐4d3) and Bi‐6p3 orbitals. Due to the temperature‐dependent electronic structure closely related to these electronic transitions, this study provides a new perspective for the design and improvement of BFO‐based temperature‐sensitive devices. [ABSTRACT FROM AUTHOR]

An efficient and economic sensing material for flexible chemical sensors is increasingly in great demand as a result of its potential application in the healthcare and environmental detection systems. Endowing the nanomaterials with high active facets serves as a promising method for the design of nanomaterials with advanced functionalities. New physicochemical properties of chemical sensor can be obtained by using high active facets nanoparticles combined in one‐dimensional (1D) nanofiber/wires. However, it remains a great challenge to conduct the development of 1D heterostructure sensing materials with high selectivity, in particular the ones that can perform under room temperature. Here, a high performance flexible sensing device based on Co3O4 nanoparticles with specific (112) facet in α‐Fe2O3 nanofiber is reported. The heterointerfaces and grain boundary allow the fast electrons transportation in sensing reactions and the (112) facets in Co3O4 nanoparticles provide a large number of highly active sites where the selective absorption of ammonia gas molecules occurs. Consequently, the flexible gas sensor exhibits ultrahigh sensitivity (417%) and mechanical stability to ammonia gas molecules, which are proved by using density functional theory calculations. A 1D heterostructure nanofiber is designed for a flexible sensing device. Highly active Co‐based catalyst in the nanofiber increases active site abundancy, specific catalytic activity and heterointerfaces. This allows for selective absorption of ammonia gas molecules by a much stronger interface interaction in the ammonia–Co3O4 (112) system as revealed by density functional theory calculations. [ABSTRACT FROM AUTHOR]

The active site of the industrial Cu/ZnO/Al2O3 catalyst used in CO2 hydrogenation to methanol has been debated for decades. Grand challenges remain in the characterization of structure, composition, and chemical state, both microscopically and spectroscopically, and complete theoretical calculations are limited when it comes to describing the intrinsic activity of the catalyst over the diverse range of structures that emerge under realistic conditions. Here a series of inverse model catalysts of ZnO on copper hydroxide were prepared where the size of ZnO was precisely tuned from atomically dispersed species to nanoparticles using atomic layer deposition. ZnO decoration boosted methanol formation to a rate of 877 gMeOH kgcat−1 h−1 with ≈80 % selectivity at 493 K. High pressure in situ X‐ray absorption spectroscopy demonstrated that the atomically dispersed ZnO species are prone to aggregate at oxygen‐deficient ZnO ensembles instead of forming CuZn metal alloys. By modeling various potential active structures, density functional theory calculations and microkinetic simulations revealed that ZnO/Cu interfaces with oxygen vacancies, rather than stoichiometric interfaces, Cu and CuZn alloys were essential to catalytic activation. [ABSTRACT FROM AUTHOR]

The active site of the industrial Cu/ZnO/Al2O3 catalyst used in CO2 hydrogenation to methanol has been debated for decades. Grand challenges remain in the characterization of structure, composition, and chemical state, both microscopically and spectroscopically, and complete theoretical calculations are limited when it comes to describing the intrinsic activity of the catalyst over the diverse range of structures that emerge under realistic conditions. Here a series of inverse model catalysts of ZnO on copper hydroxide were prepared where the size of ZnO was precisely tuned from atomically dispersed species to nanoparticles using atomic layer deposition. ZnO decoration boosted methanol formation to a rate of 877 gMeOH kgcat−1 h−1 with ≈80 % selectivity at 493 K. High pressure in situ X‐ray absorption spectroscopy demonstrated that the atomically dispersed ZnO species are prone to aggregate at oxygen‐deficient ZnO ensembles instead of forming CuZn metal alloys. By modeling various potential active structures, density functional theory calculations and microkinetic simulations revealed that ZnO/Cu interfaces with oxygen vacancies, rather than stoichiometric interfaces, Cu and CuZn alloys were essential to catalytic activation. [ABSTRACT FROM AUTHOR]

The title compounds are synthesized from mixtures of the elements in a molar ratio of K/Rb:Cu/Ag:Ge = 8:2.7:43.3 (Ta tubes, 700 °C, 7 d) and characterized by powder XRD, magnetization and heat capacity measurements, and DFT calculations. [ABSTRACT FROM AUTHOR]

Here, we present a simulation study of temperature‐dependent electronic transitions in BiVO3 (BVO) and BiNbO3 (BNO) using density functional theory (DFT) together with generalized gradient approximation (GGA) and two‐dimensional correlation analysis (2D‐CA). The results indicate that heat accumulation can accelerate the degeneracy of V‐3d orbital in BVO and the splitting of Nb‐4d orbital in BNO at 750 K. We found changes in the type of d–p hybrid orbital as follows, for BVO: V‐dx2+y2 + dZ2‐O‐2pz → V‐dx2+y2‐O‐2pz; and for BNO: Nb‐dx2+y2‐O‐2pz → Nb‐dx2+y2 + dZ2‐O‐2pz. Furthermore, we found changes in the type of hybrid orbital leading to the following electron–electron interactions, for BVO: t2g (V‐dZ2‐O‐2pz) + eg (V‐dx2+y2‐O‐2pz) → t2g (V‐dx2+y2‐O‐2pz); and for BNO: t2g + eg (Nb‐dx2+y2 + dZ2‐O‐2pz) → t2g (Nb‐dx2+y2‐O‐2pz) + eg (Nb‐dz2‐O‐2pz). The electronic transitions are determined by a charge‐transfer from the occupied O‐2p4 orbitals to the unoccupied V‐3d3 (or Nb‐4d3) and Bi‐6p3 orbitals. Due to the temperature‐dependent electronic structure closely related to these electronic transitions, this study provides a new perspective for the design and improvement of BFO‐based temperature‐sensitive devices. [ABSTRACT FROM AUTHOR]