"Dry" NiCo\begin{document}$_\textbf{2}$\end{document}O\begin{document}$_\textbf{4}$\end{document} Nanorods for Electrochemical Non-enzymatic Glucose Sensing

A rod-like NiCo\begin{document}$_2$\end{document}O\begin{document}$_4$\end{document} modified glassy carbon electrode was fabricated and used for non-enzymatic glucose sensing. The NiCo\begin{document}$_2$\end{document}O\begin{document}$_4$\end{document} was prepared by a facile hydrothermal reaction and subsequently treated in a commercial microwave oven to eliminate the residual water introduced during the hydrothermal procedure. Structural analysis showed that there was no significant structural alteration before and after microwave treatment. The elimination of water residuals was confirmed by the stoichiometric ratio change by using element analysis. The microwave treated NiCo\begin{document}$_2$\end{document}O\begin{document}$_4$\end{document} (M-NiCo\begin{document}$_2$\end{document}O\begin{document}$_4$\end{document}) showed excellent performance as a glucose sensor (sensitivity 431.29 \begin{document}$\mu $\end{document}A\begin{document}$\cdot$\end{document}mmol/L\begin{document}$^{-1}$\end{document}\begin{document}$\cdot$\end{document}cm\begin{document}$^{-2}$\end{document}). The sensing performance decreases dramatically by soaking the M-NiCo\begin{document}$_2$\end{document}O\begin{document}$_4$\end{document} in water. This result indicates that the introduction of residual water during hydrothermal process strongly affects the electrochemical performance and microwave pre-treatment is crucial for better sensory performance.     

Adiabatic Potential Energy Surfaces and Photodissociation Mechanisms for Highly Excited States of H2O

Full-dimensional adiabatic potential energy surfaces of the electronic ground state \begin{document}$ \tilde X $\end{document} and nine excited states \begin{document}$ \tilde A $\end{document}, \begin{document}$ \tilde I $\end{document}, \begin{document}$ \tilde B $\end{document}, \begin{document}$ \tilde C $\end{document}, \begin{document}$ \tilde D $\end{document}, \begin{document}$ \tilde D' $\end{document}, \begin{document}$ \tilde D'' $\end{document}, \begin{document}$ \tilde E' $\end{document} and \begin{document}$ \tilde F $\end{document} of H\begin{document}$ _2 $\end{document}O molecule are developed at the level of internally contracted multireference configuration interaction with the Davidson correction. The potential energy surfaces are fitted by using Gaussian process regression combining permutation invariant polynomials. With a large selected active space and extra diffuse basis set to describe these Rydberg states, the calculated vertical excited energies and equilibrium geometries are in good agreement with the previous theoretical and experimental values. Compared with the well-investigated photodissociation of the first three low-lying states, both theoretical and experimental studies on higher states are still limited. In this work, we focus on all the three channels of the highly excited state, which are directly involved in the vacuum ultraviolet photodissociation of water. In particular, some conical intersections of \begin{document}$ \tilde D $\end{document}-\begin{document}$ \tilde E' $\end{document}, \begin{document}$ \tilde E' $\end{document}-\begin{document}$ \tilde F $\end{document}, \begin{document}$ \tilde A $\end{document}-\begin{document}$ \tilde I $\end{document} and \begin{document}$ \tilde I $\end{document}-\begin{document}$ \tilde C $\end{document} states are clearly illustrated for the first time based on the newly developed potential energy surfaces (PESs). The nonadiabatic dissociation pathways for these excited states are discussed in detail, which may shed light on the photodissociation mechanisms for these highly excited states.     

Experimental and Theoretical Study on p-Chlorofluorobenzene in the S0, S1 and D0 States

The geometric structures and vibration frequencies of \begin{document}$ para $\end{document}-chlorofluorobenzene (\begin{document}$ p $\end{document}-ClFPh) in the first excited state of neutral and ground state of cation were investigated by resonance-enhanced multiphoton ionization and slow electron velocity-map imaging. The infrared spectrum of S\begin{document}$ _0 $\end{document} state and absorption spectrum for S\begin{document}$ _1 $\end{document}\begin{document}$ \leftarrow $\end{document}S\begin{document}$ _0 $\end{document} transition in \begin{document}$ p $\end{document}-ClFPh were also recorded. Based on the one-color resonant two-photon ionization spectrum and two-color resonant two-photon ionization spectrum, we obtained the adiabatic excited-state energy of \begin{document}$ p $\end{document}-ClFPh as 36302\begin{document}$ \pm $\end{document}4 cm\begin{document}$ ^{-1} $\end{document}. In the two-color resonant two-photon ionization slow electron velocity-map imagin spectra, the accurate adiabatic ionization potential of \begin{document}$ p $\end{document}-ClFPh was extrapolated as 72937\begin{document}$ \pm $\end{document}8 cm\begin{document}$ ^{-1} $\end{document} via threshold ionization measurement. In addition, Franck-Condon simulation was performed to help us confidently ascertain the main vibrational modes in the S\begin{document}$ _1 $\end{document} and D\begin{document}$ _0 $\end{document} states. Furthermore, the mixing of vibrational modes between S\begin{document}$ _0 $\end{document}\begin{document}$ \rightarrow $\end{document}S\begin{document}$ _1 $\end{document} and S\begin{document}$ _1 $\end{document}\begin{document}$ \rightarrow $\end{document}D\begin{document}$ _0 $\end{document} has been analyzed.     

Imaging Photodissociation Dynamics of MgO at 193 nm

In this work, we used time-sliced ion velocity imaging to study the photodissociation dynamics of MgO at \mbox{193 nm}. Three dissociation pathways are found through the speed and angular distributions of magnesium. One pathway is the one-photon excitation of MgO(X\begin{document}$^1\Sigma^+$\end{document}) to MgO(G\begin{document}$^1\Pi$\end{document}) followed by spin-orbit coupling between the G\begin{document}$^1\Pi$\end{document}, 3\begin{document}$^3\Pi$\end{document} and 1\begin{document}$^5\Pi$\end{document} states, and finally dissociated to the Mg(\begin{document}$^3$\end{document}P\begin{document}$_\textrm{u}$\end{document})+O(\begin{document}$^3$\end{document}P\begin{document}$_\textrm{g}$\end{document}) along the 1\begin{document}$^5\Pi$\end{document} surface. The other two pathways are one-photon absorption of MgO(A\begin{document}$^1\Pi$\end{document}) state to MgO(G\begin{document}$^1\Pi$\end{document}) and MgO(4\begin{document}$^1\Pi$\end{document}) state to dissociate into Mg(\begin{document}$^3$\end{document}P\begin{document}$_\textrm{u}$\end{document})+O(\begin{document}$^3$\end{document}P\begin{document}$_\textrm{g}$\end{document}) and Mg(\begin{document}$^1$\end{document}S\begin{document}$_\textrm{g}$\end{document})+O(\begin{document}$^1$\end{document}S\begin{document}$_\textrm{g}$\end{document}), respectively. The anisotropy parameters of the dissociation pathways are related to the lifetime of the vibrational energy levels and the coupling of rotational and vibronic spin-orbit states. The total kinetic energy analysis gives \begin{document}$D_0$\end{document}(Mg\begin{document}$-$\end{document}O)=21645\begin{document}$\pm$\end{document}50 cm\begin{document}$^{-1}$\end{document}.     

Theoretical Investigations on Photodissociation Dynamics of Deuterated Alkyl Halides CD3CH2F

The product branching ratio between different products in multichannel reactions is as important as the overall rate of reaction, both in terms of practical applications (\emph{e.g}. models of combustion or atmosphere chemistry) in understanding the fundamental mechanisms of such chemical reactions. A global ground state potential energy surface for the dissociation reaction of deuterated alkyl halide CD\begin{document}$ _3 $\end{document}CH\begin{document}$ _2 $\end{document}F was computed at the CCSD(T)/CBS//B3LYP/aug-cc-pVDZ level of theory for all species. The decomposition of CD\begin{document}$ _3 $\end{document}CH\begin{document}$ _2 $\end{document}F is controversial concerning C\begin{document}$ - $\end{document}F bond dissociation reaction and molecular (HF, DF, H\begin{document}$ _2 $\end{document}, D\begin{document}$ _2 $\end{document}, HD) elimination reaction. Rice-Ramsperger-Kassel-Marcus (RRKM) calculations were applied to compute the rate constants for individual reaction steps and the relative product branching ratios for the dissociation products were calculated using the steady-state approach. At the different energies studied, the RRKM method predicts that the main channel for DF or HF elimination from 1, 2-elimination of CD\begin{document}$ _3 $\end{document}CH\begin{document}$ _2 $\end{document}F is through a four-center transition state, whereas D\begin{document}$ _2 $\end{document} or H\begin{document}$ _2 $\end{document} elimination from 1, 1-elimination of CD\begin{document}$ _3 $\end{document}CH\begin{document}$ _2 $\end{document}F occurs through a direct three-center elimination. At 266, 248, and 193 nm photodissociation, the main product CD\begin{document}$ _2 $\end{document}CH\begin{document}$ _2 $\end{document}+DF branching ratios are computed to be 96.57%, 91.47%, and 48.52%, respectively; however, at 157 nm photodissociation, the product branching ratio is computed to be 16.11%. Based on these transition state structures and energies, the following photodissociation mechanisms are suggested: at 266, 248, 193 nm, CD\begin{document}$ _3 $\end{document}CH\begin{document}$ _2 $\end{document}F\begin{document}$ \rightarrow $\end{document}absorption of a photon\begin{document}$ \rightarrow $\end{document}TS5\begin{document}$ \rightarrow $\end{document}the formation of the major product CD\begin{document}$ _2 $\end{document}CH\begin{document}$ _2 $\end{document}+DF; at 157 nm, CD\begin{document}$ _3 $\end{document}CH\begin{document}$ _2 $\end{document}F\begin{document}$ \rightarrow $\end{document}absorption of a photon\begin{document}$ \rightarrow $\end{document}D/F interchange of TS1\begin{document}$ \rightarrow $\end{document}CDH\begin{document}$ _2 $\end{document}CDF\begin{document}$ \rightarrow $\end{document}H/F interchange of TS2\begin{document}$ \rightarrow $\end{document}CHD\begin{document}$ _2 $\end{document}CHDF\begin{document}$ \rightarrow $\end{document}the formation of the major product CHD\begin{document}$ _2 $\end{document}+CHDF.     

Structures,Energetics, and Infrared Spectra of the Cationic Monomethylamine-Water Clusters

The structures, energetics, and infrared (IR) spectra of the cationic monomethylamine-water clusters, [(CH\begin{document}$_3$\end{document}NH\begin{document}$_2$\end{document})(H\begin{document}$_2$\end{document}O)\begin{document}$_n$\end{document}]\begin{document}$^+$\end{document} (\begin{document}$n$\end{document}=1\begin{document}$-$\end{document}5), have been studied using quantum chemical calculations at the MP2/6-311+G(2d,p) level. The results reveal that the formation of proton-transferred CH\begin{document}$_2$\end{document}NH\begin{document}$_3$\end{document}\begin{document}$^+$\end{document} ion core structure is preferred via the intramolecular proton transfer from the methyl group to the nitrogen atom and the water molecules act as the acceptor for the O\begin{document}$\cdots$\end{document}HN hydrogen bonds with the positively charged NH\begin{document}$_3$\end{document}\begin{document}$^+$\end{document} moiety of CH\begin{document}$_2$\end{document}NH\begin{document}$_3$\end{document}\begin{document}$^+$\end{document}, whose motif is retained in the larger clusters. The CH\begin{document}$_3$\end{document}NH\begin{document}$_2$\end{document}\begin{document}$^+$\end{document} ion core structure is predicted to be less energetically favorable. Vibrational frequencies of CH stretches, hydrogen-bonded and free NH stretches, and hydrogen-bonded OH stretches in the calculated IR spectra of the CH\begin{document}$_2$\end{document}NH\begin{document}$_3$\end{document}\begin{document}$^+$\end{document} and CH\begin{document}$_3$\end{document}NH\begin{document}$_2$\end{document}\begin{document}$^+$\end{document} type structures are different from each other, which would afford the sensitive probes for fundamental understanding of hydrogen bonding networks generated from the radiation-induced chemical processes in the [(CH\begin{document}$_3$\end{document}NH\begin{document}$_2$\end{document})(H\begin{document}$_2$\end{document}O)\begin{document}$_n$\end{document}]\begin{document}$^+$\end{document} complexes.     

Low-Lying Isomers of (TiO\begin{document}$_{2}$\end{document})\begin{document}$_{n}$\end{document} (\begin{document}${n}$\end{document}=2-8) Clusters

Although there are diverse bond features of Ti and O atoms, so far only several isomers have been reported for each (TiO\begin{document}$_2$\end{document})\begin{document}$_n$\end{document} cluster. Instead of the widely used global optimization, in this work, we search for the low-lying isomers of (TiO\begin{document}$_2$\end{document})\begin{document}$_n$\end{document} (\begin{document}$n$\end{document}=2\begin{document}$-$\end{document}8) clusters with up to 10000 random sampling initial structures. These structures were optimized by the PM6 method, followed by density functional theory calculations. With this strategy, we have located many more low-lying isomers than those reported previously. The number of isomers increases dramatically with the size of the cluster, and about 50 isomers were found for (TiO\begin{document}$_2$\end{document})\begin{document}$_7$\end{document} and (TiO\begin{document}$_2$\end{document})\begin{document}$_8$\end{document} with the energy within kcal/mol. Furthermore, new lowest isomers have been located for (TiO\begin{document}$_2$\end{document})\begin{document}$_5$\end{document} and (TiO\begin{document}$_2$\end{document})\begin{document}$_8$\end{document}, and isomers with three terminal oxygen atoms, five coordinated oxygen atoms as well as six coordinated titanium atoms have been located. Our work highlights the diverse structural features and a large number of isomers of small TiO\begin{document}$_2$\end{document} clusters.     

Theoretical Studies on Dihedral Angle-Bending Isomers of M2Pt20/-Clusters

The structures and electronic properties of the gaseous M\begin{document}$ _2 $\end{document}Pt\begin{document}$ _2 $\end{document}\begin{document}$ ^{0/-} $\end{document} clusters (M represents the alkaline earth metal) were investigated using the density functional theory (B3LYP and PBE0) and wave function theory (SCS-MP2, CCSD and CCSD (T)). The results indicate that the D\begin{document}$ _{2{h}} $\end{document} isomers with the planar structures are more stable than the C\begin{document}$ _{2v} $\end{document} isomers with smaller dihedral angles and shorter Pt-Pt bond lengths. The mutual competition of M(s, p)-Pt(5d) interaction and Pt-Pt covalent bonding contributes to the different stabilizations of the two kinds of isomers. The M(s, p)-Pt(5d) interaction favors the planar isomers with D\begin{document}$ _{2h} $\end{document} symmetry, while the Pt-Pt covalent bonding leads to the C\begin{document}$ _{2v} $\end{document} isomers with bending structures. Two different crossing points are determined in the potential energy curves of Be\begin{document}$ _2 $\end{document}Pt\begin{document}$ _2 $\end{document} with the singlet and triplet states. But there is just one crossing point in potential energy curves of Ra\begin{document}$ _2 $\end{document}Pt\begin{document}$ _2 $\end{document} and Ca\begin{document}$ _2 $\end{document}Pt\begin{document}$ _2 $\end{document}\begin{document}$ ^- $\end{document} because of flatter potential energy curves of Ra\begin{document}$ _2 $\end{document}Pt\begin{document}$ _2 $\end{document} with the triplet state or Ca\begin{document}$ _2 $\end{document}Pt\begin{document}$ _2 $\end{document}\begin{document}$ ^- $\end{document} with quartet state. The results reveal a unique example of dihedral angle-bending isomers with the smallest number of atoms and may help the understanding of the bonding properties of other potential angle-bending isomers.     

Physical Properties of Si2Ge and SiGe2 in Hexagonal Symmetry: First-Principles Calculations

We predict two novel group 14 element alloys Si\begin{document}$_2$\end{document}Ge and SiGe\begin{document}$_2$\end{document} in \begin{document}$P$\end{document}6\begin{document}$_2$\end{document}22 phase in this work through first-principles calculations. The structures, stability, elastic anisotropy, electronic and thermodynamic properties of these two proposed alloys are investigated systematically. The proposed \begin{document}$P$\end{document}6\begin{document}$_2$\end{document}22-Si\begin{document}$_2$\end{document}Ge and \begin{document}$P$\end{document}6\begin{document}$_2$\end{document}22-SiGe\begin{document}$_2$\end{document} have a hexagonal symmetry structure, and the phonon dispersion spectra and elastic constants indicate that these two alloys are dynamically and mechanically stable at ambient pressure. The elastic anisotropy properties of \begin{document}$P$\end{document}6\begin{document}$_2$\end{document}22-Si\begin{document}$_2$\end{document}Ge and \begin{document}$P$\end{document}6\begin{document}$_2$\end{document}22-SiGe\begin{document}$_2$\end{document} are examined elaborately by illustrating the surface constructions of Young's modulus, the contour surfaces of shear modulus, and the directional dependence of Poisson's ratio; the differences with their corresponding group 14 element allotropes \begin{document}$P$\end{document}6\begin{document}$_2$\end{document}22-Si\begin{document}$_3$\end{document} and \begin{document}$P$\end{document}6\begin{document}$_2$\end{document}22-Ge\begin{document}$_3$\end{document} are also discussed and compared. Moreover, the Debye temperature and sound velocities are analyzed to study the thermodynamic properties of the proposed \begin{document}$P$\end{document}6\begin{document}$_2$\end{document}22-Si\begin{document}$_2$\end{document}Ge and \begin{document}$P$\end{document}6\begin{document}$_2$\end{document}22-SiGe\begin{document}$_2$\end{document}.     

Gamma Ray Radiation Effect on \begin{document}$\rm{{Bi}}_{2}$\end{document}W\begin{document}$\rm{{O}}_{6}$\end{document} Photocatalyst

The development of \begin{document}$\rm{Bi}_2$\end{document}W\begin{document}$\rm{O}_6$\end{document}-based materials has become one of research hotspots due to the increasing demands on high-efficient photocatalyst responding to visible light. In this work, the effect of high energy radiation (\begin{document}$\gamma$\end{document}-ray) on the structure and the photocatalytic activity of \begin{document}$\rm{Bi}_2$\end{document}W\begin{document}$\rm{O}_6$\end{document} nanocrystals was first studied. No morphological change of \begin{document}$\rm{Bi}_2$\end{document}W\begin{document}$\rm{O}_6$\end{document} nanocrystals was observed by SEM under \begin{document}$\gamma$\end{document}-ray radiation. However, the XRD spectra of the irradiated \begin{document}$\rm{Bi}_2$\end{document}W\begin{document}$\rm{O}_6$\end{document} nanocrystals showed the characteristic 2\begin{document}$\theta$\end{document} of (113) plane shifts slightly from 28.37\begin{document}$^{\rm{o}}$\end{document} to 28.45\begin{document}$^{\rm{o}}$\end{document} with the increase of the absorbed dose, confirming the change in the crystal structure of \begin{document}$\rm{Bi}_2$\end{document}W\begin{document}$\rm{O}_6$\end{document}. The XPS results proved the crystal structure change was originated from the generation of oxygen vacancy defects under high-dose radiation. The photocatalytic activity of \begin{document}$\rm{Bi}_2$\end{document}W\begin{document}$\rm{O}_6$\end{document} on the decomposition of methylene blue (MB) in water under visible light increases gradually with the increase of absorbed dose. Moreover, the improved photocatalytic performance of the irradiated \begin{document}$\rm{Bi}_2$\end{document}W\begin{document}$\rm{O}_6$\end{document} nanocrystals remained after three cycles of photocatalysis, indicating a good stability of the created oxygen vacancy defects. This work gives a new simple way to improve photocatalytic performance of \begin{document}$\rm{Bi}_2$\end{document}W\begin{document}$\rm{O}_6$\end{document} through creating oxygen vacancy defects in the crystal structure by \begin{document}$\gamma$\end{document}-ray radiation.     

Improving Interfacial Electrochemistry of LiNi0.5Mn1.5O4 Cathode Coated by Mn3O4

In this work the surface of LiNi\begin{document}$_{0.5}$\end{document}Mn\begin{document}$_{1.5}$\end{document}O\begin{document}$_{4}$\end{document} (LMN) particles is modified by Mn\begin{document}$_{3}$\end{document}O\begin{document}$_{4}$\end{document} coating through a simple wet grinding method, the electronic conductivity is significantly improved from 1.53\begin{document}$\times$\end{document}10\begin{document}$^{-7}$\end{document} S/cm to 3.15\begin{document}$\times$\end{document}10\begin{document}$^{-5}$\end{document} S/cm after 2.6 wt% Mn\begin{document}$_{3}$\end{document}O\begin{document}$_{4}$\end{document} coating. The electrochemical test results indicate that Mn\begin{document}$_{3}$\end{document}O\begin{document}$_{4}$\end{document} coating dramatically enhances both rate performance and cycling capability (at 55 ℃) of LNM. Among the samples, 2.6 wt% Mn\begin{document}$_{3}$\end{document}O\begin{document}$_{4}$\end{document}-coated LNM not only exhibits excellent rate capability (a large capacity of 108 mAh/g at 10 C rate) but also shows 78% capacity retention at 55 ℃ and 1 C rate after 100 cycles.     

Experimental and Theoretical Study on Dissociative Photoionization of Cyclopentanone

The dissociative photoionization of cyclopentanone was investigated by means of a reflectron time-of-flight mass spectrometer (RTOF-MS) with tunable vacuum ultraviolet synchrotron radiation in the photon energy range of 9.0-15.5 eV. The photoionization efficiency (PIE) curves for molecular ion and fragment ions were measured. The ionization energy of cyclopentanone was determined to be 9.23\begin{document}$\pm$\end{document}0.03 eV. Fragment ions from the dissociative photoionization of cyclopentanone were identified as C\begin{document}$_5$\end{document}H\begin{document}$_7$\end{document}O\begin{document}$^+$\end{document}, C\begin{document}$_4$\end{document}H\begin{document}$_5$\end{document}O\begin{document}$^+$\end{document}, C\begin{document}$_4$\end{document}H\begin{document}$_8^+$\end{document}/C\begin{document}$_3$\end{document}H\begin{document}$_4$\end{document}O\begin{document}$^+$\end{document}, C\begin{document}$_3$\end{document}H\begin{document}$_3$\end{document}O\begin{document}$^+$\end{document}, C\begin{document}$_4$\end{document}H\begin{document}$_6^+$\end{document}, C\begin{document}$_2$\end{document}H\begin{document}$_4$\end{document}O\begin{document}$^+$\end{document}, C\begin{document}$_3$\end{document}H\begin{document}$_6^+$\end{document}, C\begin{document}$_3$\end{document}H\begin{document}$_5^+$\end{document}, C\begin{document}$_3$\end{document}H\begin{document}$_4^+$\end{document}, C\begin{document}$_3$\end{document}H\begin{document}$_3^+$\end{document}, C\begin{document}$_2$\end{document}H\begin{document}$_5^+$\end{document} and C\begin{document}$_2$\end{document}H\begin{document}$_4^+$\end{document}. With the aid of the ab initio calculations at the \begin{document}$\omega$\end{document}B97X-D/6-31+G(d, p) level of theory, the dissociative mechanisms of C\begin{document}$_5$\end{document}H\begin{document}$_8$\end{document}O\begin{document}$^+$\end{document} are proposed. Ring opening and hydrogen migrations are the predominant processes in most of the fragmentation pathways of cyclopentanone.     

Three-Dimensional Diabatic Potential Energy Surfaces of Thiophenol with Neural Networks

Three-dimensional (3D) diabatic potential energy surfaces (PESs) of thiophenol involving the S\begin{document}$_0$\end{document}, and coupled \begin{document}$^1$\end{document}\begin{document}$\pi\pi^*$\end{document} and \begin{document}$^1$\end{document}\begin{document}$\pi\sigma^*$\end{document} states were constructed by a neural network approach. Specifically, the diabatization of the PESs for the \begin{document}$^1$\end{document}\begin{document}$\pi\pi^*$\end{document} and \begin{document}$^1\pi\sigma^*$\end{document} states was achieved by the fitting approach with neural networks, which was merely based on adiabatic energies but with the correct symmetry constraint on the off-diagonal term in the diabatic potential energy matrix. The root mean square errors (RMSEs) of the neural network fitting for all three states were found to be quite small (\begin{document}$<$\end{document}4 meV), which suggests the high accuracy of the neural network method. The computed low-lying energy levels of the S\begin{document}$_0$\end{document} state and lifetime of the 0\begin{document}$^0$\end{document} state of S\begin{document}$_1$\end{document} on the neural network PESs are found to be in good agreement with those from the earlier diabatic PESs, which validates the accuracy and reliability of the PESs fitted by the neural network approach.     

Redox Controllable Switch of Crystalline Phase and Physical Property in SrVO\begin{document}$_{x}$\end{document} Epitaxial Films

Transition-metal oxides have attracted much attention due to its abundant crystalline phases and intriguing physical properties. However, some of these compounds are difficult to be fabricated directly in film form due to the ease of valence variation of transition-metal elements. In this work, we reveal the reversible structural transition between SrVO\begin{document}$_3$\end{document} and Sr\begin{document}$_2$\end{document}V\begin{document}$_2$\end{document}O\begin{document}$_7$\end{document} films via thermal treatment in oxygen atmosphere or in vacuum. Based on this, Sr\begin{document}$_2$\end{document}V\begin{document}$_2$\end{document}O\begin{document}$_7$\end{document} epitaxial films are successfully synthesized and studied. Property characterizations show that the semitransparent and metallic SrVO\begin{document}$_3$\end{document} could reversibly switch into transparent and insulating Sr\begin{document}$_2$\end{document}V\begin{document}$_2$\end{document}O\begin{document}$_7$\end{document}, implying potential applications in controllable electronic and optical devices.     

Designer Mg-Mg and Zn-Zn Single Bonds Facilitated by Double Aromaticity in the M2B7-(M=Mg,Zn) Clusters

The simple homodinuclear M

\begin{document}$ - $\end{document}

M single bonds for group II and XII elements are difficult to obtain as a result of the fulfilled s

\begin{document}$ ^2 $\end{document}

electronic configurations, consequently, a dicationic prototype is often utilized to design the M

\begin{document}$ ^+ $\end{document}\begin{document}$ - $\end{document}

M

\begin{document}$ ^+ $\end{document}

single bond. Existing studies generally use sterically bulky organic ligands L

\begin{document}$ ^- $\end{document}

to synthesize the compounds in the L

\begin{document}$ ^- $\end{document}\begin{document}$ - $\end{document}

M

\begin{document}$ ^+ $\end{document}\begin{document}$ - $\end{document}

M

\begin{document}$ ^+ $\end{document}\begin{document}$ - $\end{document}

L

\begin{document}$ ^- $\end{document}

manner. However, here we report the design of Mg

\begin{document}$ - $\end{document}

Mg and Zn

\begin{document}$ - $\end{document}

Zn single bonds in two ligandless clusters, Mg

\begin{document}$ _2 $\end{document}

B

\begin{document}$ _7 $\end{document}\begin{document}$ ^- $\end{document}

and Zn

\begin{document}$ _2 $\end{document}

B

\begin{document}$ _7 $\end{document}\begin{document}$ ^- $\end{document}

, using density functional theory methods. The global minima of both of the clusters are in the form of M

\begin{document}$ _2 $\end{document}\begin{document}$ ^{2+} $\end{document}

(B

\begin{document}$ _7 $\end{document}\begin{document}$ ^{3-} $\end{document}

), where the M

\begin{document}$ - $\end{document}

M single bonds are positioned above a quasi-planar hexagonal B

\begin{document}$ _7 $\end{document}

moiety. Chemical bonding analyses further confirm the existence of Mg

\begin{document}$ - $\end{document}

Mg and Zn

\begin{document}$ - $\end{document}

Zn single bonds in these clusters, which are driven by the unusually stable B

\begin{document}$ _7 $\end{document}\begin{document}$ ^{3-} $\end{document}

moiety that is both

\begin{document}$ \sigma $\end{document}

and

\begin{document}$ \pi $\end{document}

aromatic. Vertical detachment energies of Mg

\begin{document}$ _2 $\end{document}

B

\begin{document}$ _7 $\end{document}\begin{document}$ ^- $\end{document}

and Zn

\begin{document}$ _2 $\end{document}

B

\begin{document}$ _7 $\end{document}\begin{document}$ ^- $\end{document}

are calculated to be 2.79 eV and 2.94 eV, respectively, for the future comparisons with experimental data.

     

DFT Study on the Catalytic Role of \begin{document}$\alpha$\end{document}-MoC(100) in Methanol Steam Reforming

In this work, we investigated the methanol steam reforming (MSR) reaction (CH\begin{document}$_3$\end{document}OH+H\begin{document}$_2$\end{document}O \begin{document}$\rightarrow$\end{document}CO\begin{document}$_2$\end{document}+3H\begin{document}$_2$\end{document}) catalyzed by \begin{document}$\alpha$\end{document}-MoC by means of density functional theory calculations. The adsorption behavior of the relevant intermediates and the kinetics of the elementary steps in the MSR reaction are systematically investigated. The results show that, on the \begin{document}$\alpha$\end{document}-MoC(100) surface, the O\begin{document}$-$\end{document}H bond cleavage of CH\begin{document}$_3$\end{document}OH leads to CH\begin{document}$_3$\end{document}O, which subsequently dehydrogenates to CH\begin{document}$_2$\end{document}O. Then, the formation of CH\begin{document}$_2$\end{document}OOH between CH\begin{document}$_2$\end{document}O and OH is favored over the decomposition to CHO and H. The sequential dehydrogenation of CH\begin{document}$_2$\end{document}OOH results in a high selectivity for CO\begin{document}$_2$\end{document}. In contrast, the over-strong adsorption of the CH\begin{document}$_2$\end{document}O intermediate on the \begin{document}$\alpha$\end{document}-MoC(111) surface leads to its dehydrogenation to CO product. In addition, we found that OH species, which is produced from the facile water activation, help the O\begin{document}$-$\end{document}H bond breaking of intermediates by lowering the reaction energy barrier. This work not only reveals the catalytic role played by \begin{document}$\alpha$\end{document}-MoC(100) in the MSR reaction, but also provides theoretical guidance for the design of \begin{document}$\alpha$\end{document}-MoC-based catalysts.     

Photochemistry of Potassium Ferrocyanide and its Reaction with Uridine 5′-monophosphate in Aqueous Solution under Ultraviolet Irradiation

The photochemical reaction of potassium ferrocyanide (K\begin{document}$ _4 $\end{document}Fe(CN)\begin{document}$ _6 $\end{document}) exhibits excitation wavelength dependence and non-Kasha rule behavior. In this study, the excited-state dynamics of K\begin{document}$ _4 $\end{document}Fe(CN)\begin{document}$ _6 $\end{document} were studied by transient absorption spectroscopy. Excited state electron detachment (ESED) and photoaquation reactions were clarified by comparing the results of 260, 320, 340, and 350 nm excitations. ESED is the path to generate a hydrated electron (e\begin{document}$ _{\rm{aq}}^{-} $\end{document}). ESED energy barrier varies with the excited state, and it occurs even at the first singlet excited state (\begin{document}$ ^{1} $\end{document}T\begin{document}$ _{\rm{1g}} $\end{document}). The \begin{document}$ ^{1} $\end{document}T\begin{document}$ _{\rm{1g}} $\end{document} state shows \begin{document}$ {\sim} $\end{document}0.2 ps lifetime and converts into triplet [Fe(CN)\begin{document}$ _{6} $\end{document}]\begin{document}$ ^{4-} $\end{document} by intersystem crossing. Subsequently, \begin{document}$ ^{3} $\end{document}[Fe(CN)\begin{document}$ _{5} $\end{document}]\begin{document}$ ^{3-} $\end{document} appears after one CN\begin{document}$ ^{-} $\end{document} ligand is ejected. In sequence, H\begin{document}$ _{2} $\end{document}O attacks [Fe(CN)\begin{document}$ _{5} $\end{document}]\begin{document}$ ^{3-} $\end{document} to generate [Fe(CN)\begin{document}$ _{5} $\end{document}H\begin{document}$ _{2} $\end{document}O]\begin{document}$ ^{3-} $\end{document} with a time constant of approximately 20 ps. The \begin{document}$ ^{1} $\end{document}T\begin{document}$ _{\rm{1g}} $\end{document} state and e\begin{document}$ _{\rm{aq}}^{-} $\end{document} exhibit strong reducing power. The addition of uridine 5\begin{document}$ ' $\end{document}-monophosphate (UMP) to the K\begin{document}$ _{4} $\end{document}Fe(CN)\begin{document}$ _{6} $\end{document} solution decrease the yield of e\begin{document}$ _{\rm{aq}}^{-} $\end{document} and reduce the lifetimes of the e\begin{document}$ _{\rm{aq}}^{-} $\end{document} and \begin{document}$ ^{1} $\end{document}T\begin{document}$ _{\rm{1g}} $\end{document} state. The obtained reaction rate constant of \begin{document}$ ^{1} $\end{document}T\begin{document}$ _{\rm{1g}} $\end{document} state and UMP is 1.7\begin{document}$ {\times} $\end{document}10\begin{document}$ ^{14} $\end{document} (mol/L)\begin{document}$ ^{-1}\cdot $\end{document}s\begin{document}$ ^{-1} $\end{document}, and the e\begin{document}$ _{\rm{aq}}^{-} $\end{document} attachment to UMP is \begin{document}$ {\sim} $\end{document}8\begin{document}$ {\times} $\end{document}10\begin{document}$ ^{9} $\end{document} (mol/L)\begin{document}$ ^{-1}\cdot $\end{document}s\begin{document}$ ^{-1} $\end{document}. Our results indicate that the reductive damage of K\begin{document}$ _{4} $\end{document}Fe(CN)\begin{document}$ _{6} $\end{document} solution to nucleic acids under ultraviolet irradiation cannot be neglected.     

Location Effect in a Photocatalytic Hybrid System of Metal-Organic Framework Interfaced with Semiconductor Nanoparticles

We report an ultrafast spectroscopy investigation that addresses the subtle location effect in a prototypical semiconductor-MOF hybrid system with TiO\begin{document}$_2$\end{document} nanoparticles being incorporated inside or supported onto Cu\begin{document}$_3$\end{document}(BTC)\begin{document}$_2$\end{document}, denoted as TiO\begin{document}$_2$\end{document}@Cu\begin{document}$_3$\end{document}(BTC)\begin{document}$_2$\end{document} and TiO\begin{document}$_2$\end{document}/Cu\begin{document}$_3$\end{document}(BTC)\begin{document}$_2$\end{document}, respectively. By tracking in real time the interface electron dynamics in the hybrid system, we find that the interface states formed between TiO\begin{document}$_2$\end{document} and Cu\begin{document}$_3$\end{document}(BTC)\begin{document}$_2$\end{document} can act as an effective relay for electron transfer, whose efficiency rests on the relative location of the two components. It is such a subtle location effect that brings on difference in photocatalytic CO\begin{document}$_2$\end{document} reduction using the two semiconductor-MOF hybrids. The mechanistic understanding of the involved interface electron-transfer behavior and effect opens a helpful perspective for rational design of MOF-based hybrid systems for photoelectrochemical applications.     

Reinvestigate the C2Π-X2Π(0,0) Band of AgO

The \begin{document}$ C^2\Pi $\end{document}-\begin{document}$ X^2\Pi $\end{document}(0, 0) band of AgO has been reinvestigated by laser induced fluorescence spectroscopy with a spectral resolution of \begin{document}$ \sim $\end{document}0.02 cm\begin{document}$ ^{-1} $\end{document}. The AgO molecules are produced by discharging a gas mixture of O\begin{document}$ _2 $\end{document}/Ar with silver needle electrodes in a supersonic jet expansion. By employing a home-made narrowband single longitude mode optical parametric oscillator (SLM-OPO) as the laser source, high-resolution spectra of the \begin{document}$ C^2\Pi $\end{document}-\begin{document}$ X^2\Pi $\end{document}(0, 0) band have been recorded for both \begin{document}$ ^{107} $\end{document}Ag\begin{document}$ ^{16} $\end{document}O and \begin{document}$ ^{109} $\end{document}Ag\begin{document}$ ^{16} $\end{document}O isotopologues. The spectroscopic constants of the \begin{document}$ C^2\Pi $\end{document} state are consequently determined, with the \begin{document}$ ^{109} $\end{document}Ag\begin{document}$ ^{16} $\end{document}O one being reported for the first time. The nature of the spin-orbit coupling effect in the \begin{document}$ C^2\Pi $\end{document} state is proposed to be due to state mixing with the nearby repulsive \begin{document}$ ^{4}\Sigma^{-} $\end{document} and \begin{document}$ ^{4}\Pi $\end{document} states.     

Ag-Cu Nanoparticles Supported on N-Doped TiO\begin{document}$_2$\end{document} Nanowire Arrays for Efficient Photocatalytic CO\begin{document}$_2$\end{document} Reduction

Photocatalytic reduction of CO\begin{document}$_2$\end{document} into various types of fuels has attracted great interest, and serves as a potential solution to addressing current global warming and energy challenges. In this work, Ag-Cu nanoparticles are densely supported on N-doped TiO\begin{document}$_2$\end{document} nanowire through a straightforward nanofabrication approach. The range of light absorption by N-doped TiO\begin{document}$_2$\end{document} can be tuned to match the plasmonic band of Ag nanoparticles, which allows synergizing a resonant energy transfer process with the Schottky junction. Meanwhile, Cu nanoparticles can provide active sites for the reduction of CO\begin{document}$_2$\end{document} molecules. Remarkably, the performance of photocatalytic CO\begin{document}$_2$\end{document} reduction is improved to produce CH\begin{document}$_4$\end{document} at a rate of 720 \begin{document}$\mu$\end{document}mol\begin{document}$\cdot$\end{document}g\begin{document}$^{-1}$\end{document}\begin{document}$\cdot$\end{document}h\begin{document}$^{-1}$\end{document} under full-spectrum irradiation.