Aqueous battery with nonflammable and instinctive safe properties has received great attention. However, issues related to Zn anode such as side reactions and rampant dendrite growth hinder the long-term circulation of AZMBs. Herein, an ultrathin(35 nm) MoO coating is deposited on the Zn anode by means of vacuum vapor deposition for the first time.
View Article and Find Full Text PDFPolyanionic AV(PO) (A = Li, Na) with open channels have been extensively utilized as cathode materials for aqueous zinc-metal batteries (AZMBs), whereas suffering from severe capacity fading and rapid operation voltage decay during cycling. when used as In this work, it is disclosed that the rapid degradation is induced by an irreversible phase change from electrochemical active LiV(PO) to nonactive monoclinic LiZnPO, as well as active NaV(PO) to nonactive rhombic Zn(PO)(HO). Subsequently, a rational dual-cation (Al-Fe) doping strategy is proposed to suppress these detrimental transformations.
View Article and Find Full Text PDFStudying the chiral characteristics and chiral inversion mechanisms of gold nanoclusters is important to promote their applications in the field of chiral catalysis and chiral recognition. Herein, we investigated the chiral inversion process of the Au(SR) nanocluster and its derivatives using density functional theory calculations. The results showed that the chiral inversion process can be achieved by rotation of tetrahedra units in the gold core without breaking the Au-S bond.
View Article and Find Full Text PDFThe irreversible oxygen-redox reactions in the high-voltage region of sodium-layered cathode materials lead to poor capacity retention and structural instability during cycling, presenting a significant challenge in the development of high-energy-density sodium-ion batteries. This work introduces a high-entropy design for layered NaLiCoCuNiTiMnO (Mn-HEO) cathode with a self-regulating mechanism to extend specific capacity and energy density. The oxygen redox reaction was activated during the initial charging process, accompanied by the self-regulation of active elements, enhancing the ionic bonds to form a vacancy wall near the TM vacancies and thus preventing the migration of transition metal elements.
View Article and Find Full Text PDFAtomic doping in catalysts is an effective strategy for adjusting their catalytic activity, which has recently been applied to promote sulfur reduction reactions (SRRs) on the cathode of lithium-sulfur (Li-S) batteries. Herein, the electrocatalytic SRR mechanism of eight metal atom (Ca, Ti, V, Cr, Mn, Fe, Co or Ni) doped Chevrel phase MoSe were investigated using density functional theory (DFT) calculations. The results reveal that the interaction between polysulfides and the catalyst mainly originates from the coupling of d and d orbitals of doped metals and the 3p orbitals of S.
View Article and Find Full Text PDFSingle-atom catalysts are proven to be an effective strategy for suppressing shuttle effect at the source by accelerating the redox kinetics of intermediate polysulfides in lithium-sulfur (Li-S) batteries. However, only a few 3d transition metal single-atom catalysts (Ti, Fe, Co, Ni) are currently applied for sulfur reduction/oxidation reactions (SRR/SOR), which remains challenging for screening new efficient catalysts and understanding the relationship between structure-activity of catalysts. Herein, N-doped defective graphene (NG) supported 3d, 4d, and 5d transition metals are used as single-atom catalyst models to explore electrocatalytic SRR/SOR in Li-S batteries by using density functional theory calculations.
View Article and Find Full Text PDFLiOX (X = Cl, Br), a lithium-rich anti-perovskite material developed in recent years, has received tremendous attention due to its high ionic conductivity of >10 S cm at room temperature. However, the origin of the high ionic conductivity of the material at the atomic level is still not clear. In this work, we investigated the dynamic behavior of the LiOCl system with three different defect structures (Li-Frenkel, LiCl-Schottky, and Cl-O anti-site disorder) at seven temperature intervals and calculated its ionic conductivity using the deep potential (DP) model.
View Article and Find Full Text PDFRatiometric fluorescent probes could effectively offset the changes of the autofluorescence and compartmental localization. FRET, ICT, etc. are the common strategies to design probes for biosensing, but these strategies have some deficiencies.
View Article and Find Full Text PDFTwo novel aromatic imides, diarylcyclopentadienone-fused naphthalimides (BCPONI-2Br and TCPONI-2Br), are designed and synthesized by condensation coupling cyclopentadienone derivatives at the lateral position of naphthalimide skeleton. It has been found that BCPONI-2Br and TCPONI-2Br are highly electron-withdrawing acceptor moieties, which possess broad absorption bands and very low-lying LUMO energy levels, as low as -4.02 eV.
View Article and Find Full Text PDFUnderstanding the structure and structure-property relationship of atomic and ligated clusters is one of the central research tasks in the field of cluster research. In chemistry, empirical rules such as the polyhedral skeleton electron pair theory (PSEPT) approach had been outlined to account for skeleton structures of many main-group atomic and ligand-protected transition metal clusters. Nonetheless, because of the diversity of cluster structures and compositions, no uniform structural and electronic rule is available for various cluster compounds.
View Article and Find Full Text PDFCoinage metal clusters stabilized by organic ligands such as phosphine or organothiolate are well known to possess multi-twinned gold cores, and the face-centered-cubic (fcc) metal atom packing is unstable until the cluster size reaches a certain threshold. In this study, we searched for the smallest size gold nanocrystal protected by thiolate ligands by means of the crystal facet cleavage (CFC) method. Starting from the nanocrystal-like Au28(SR)20 cluster, after cleaving two different crystal facets and patching the ligand shells, we obtained five nanocrystal-like Au20(SR)16 isomers.
View Article and Find Full Text PDFThe atomic structures of many atomically precise nanosized ligand protected gold clusters have been resolved recently. However, the determination of the atomic structures of large sized ligand protected gold clusters containing metal atoms over ∼100 is still a grand challenge. The lack of structural information of these larger sized clusters has greatly hindered the understanding of the structure evolution and structure-property relations of ligand protected gold nanoclusters.
View Article and Find Full Text PDFA novel ladderlike fused-ring donor, dithienocyclopentacarbazole (DTCC) derivative, is used to design and synthesize three novel donor-acceptor-π-acceptor-type organic dyes (C1-C3) via facile direct arylation reactions, in which the DTCC derivative substituted by four -octyloxyphenyl groups is served as the electron donor and the carboxylic acid group is used as the electron acceptor or anchoring group. To fine-tune the optical, electrochemical, and photovoltaic properties of the three dyes, various auxiliary acceptors, including benzo[2,1,3]thiadiazole (BT), 5,6-difluorobenzo[2,1,3]thiadiazole (DFBT), and pyridal[2,1,3]thiadiazole (PT), are incorporated into the dye backbones. The results indicate that all of the three dyes exhibit strong light-capturing ability in the visible region and obtain relatively high molar extinction coefficients (>31 000 M cm) due to their strong charge transfer (CT) from donor to acceptor.
View Article and Find Full Text PDFAs an important intermediate link between the smaller and larger size thiolate-protected gold nanoparticles (RS-AuNPs), the molecular formula and atomic structure of the ∼14 kDa core-mass RS-AuNP species (containing around 70 core gold atoms) have not been determined unambiguously. In this work, we theoretically predict an unprecedented ∼14 kDa core-mass AuNP species, denoted as Au(SR), which is composed a symmetric, face-centered-cubic (fcc) 68-gold atom framework. The fcc gold kernel in the Au(SR) is made of eight 13-atom Au-cubotahedrons sharing 12 square faces, showing a standard 2 × 2 × 2 magic cube formula.
View Article and Find Full Text PDFThe atomic structure of a ten-electron (10e) thiolate-protected gold cluster, denoted as Au(SR), was theoretically predicted. Based on the prediction of the atomic structure of the 10e Au(SR) cluster, we proposed a novel 'gold-atom insertion, thiolate-group elimination' mechanism to understand the structural evolution of the face-centered-cubic (fcc) thiolate-protected gold clusters. The key step of structural evolution from Au(SR) to Au(SR) and then to the Au(SR) cluster, i.
View Article and Find Full Text PDFBased on the recently reported atomic structures of thiolate-protected Au(SR), Au(SR), Au(SR), and Au(SR) clusters, a family of homogeneous, linear, thiolate-protected gold superstructures containing novel quasi-face-centered-cubic (quasi-fcc) Au-cores is theoretically envisioned, denoted as the Au(SR) cluster. By means of density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations, a unified view of the geometric structure, electronic structure, magic stable size and size-dependent NIR absorption properties of Au(SR) clusters is provided. We find that the Au(SR) clusters demonstrate oscillating transformation energies dependent on N.
View Article and Find Full Text PDFThe larger size gold nanoparticles typically adopt a face-centered cubic (fcc) atomic packing, while in the ultrasmall nanoclusters the packing styles of Au atoms are diverse, including fcc, hexagonal close packing (hcp), and body-centered cubic (bcc), depending on the ligand protection. The possible conversion between these packing structures is largely unknown. Herein, we report the growth of a new Au21(S-Adm)15 nanocluster (S-Adm = adamantanethiolate) from Au18(SR)14 (SR = cyclohexylthiol), with the total structure determined by X-ray crystallography.
View Article and Find Full Text PDFIn this study, Li-rich cathode, 0.4Li2MnO3·0.6LiNi1/3Co1/3Mn1/3O2 was synthesized by a resorcinol formaldehyde assisted sol-gel method for the first time.
View Article and Find Full Text PDFPhilos Trans A Math Phys Eng Sci
April 2014
Double-docking self-assembled monolayers (DDSAMs), namely self-assembled monolayers (SAMs) formed by molecules possessing two docking groups, provide great flexibility to tune the work function of metal electrodes and the tunnelling barrier between metal electrodes and the SAMs, and thus offer promising applications in both organic and molecular electronics. Based on the dispersion-corrected density functional theory (DFT) in comparison with conventional DFT, we carry out a systematic investigation on the dual configurations of a series of DDSAMs on an Au(111) surface. Through analysing the interface electronic structures, we obtain the relationship between single molecular properties and the SAM-induced work-function modification as well as the level alignment between the metal Fermi level and molecular frontier states.
View Article and Find Full Text PDFDensity functional theory calculations are used to investigate the electronic structure of pyridine-based self-assembled monolayers (SAMs) on an Au(111) surface. We find that, when using pyridine docking groups, the bonding-induced charge rearrangements are frequently found to extend well onto the molecular backbone. This is in contrast to previous observations for the chemisorption of other SAMs, e.
View Article and Find Full Text PDFSelf-assembled monolayers (SAMs) of functionalized thiols are widely used in organic (opto)electronic devices to tune the work function, Phi, of noble-metal electrodes and, thereby, to optimize the barriers for charge-carrier injection. The achievable Phi values not only depend on the intrinsic molecular dipole moment of the thiols but, importantly, also on the bond dipole at the Au-S interface. Here, on the basis of extensive density-functional theory calculations, we clarify the ongoing controversy regarding the existence, the magnitude, and the nature of that bond dipole.
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