As promising building blocks for molecular electronics, organic molecules have attracted intense research interest. Metal-molecule-metal junctions are often used as testbeds for studying organic molecules’ charge transport properties. In this article, fabrication methods, nanoscalability and addressability of these junctions are reviewed. Fabrication approaches are classified into soft contact, scanning probe microscopy, against-nanowire, crossed-wire, shadow angle evaporation and nanopore junctions. The effects of preparation method on the junction charge transport properties are systematically discussed. In general, the scanning tunneling microscopy technique is suitable for fast screening of molecular conductance, but cannot address junction that limits their in-situ temperature-dependent characterizations. The nanopore junction guarantees od control over the device size and the intrinsic contact stability, however, the nature of the electrode-molecule interface is not well understood. Shadow angle evaporation and soft contact techniques can effectively reduce the possibility of device short circuiting; however, the electrode dimensions limit potential applications. The against-nanowire method provides an easy way to fabricate addressable junctions, and if combined with the crossed-wire procedure may have potential for fabrication and three-dimensional integration of molecular junctions.

The response of the mechanisms of the α polymorph of CL-20 (α-CL-20) to high temperature is important for understanding the phenomenon of shock initiation, shock ignition, and detonation. The thermal decomposition of α-CL-20 hydrate and pure α-CL-20 were studied by ReaxFF reactive molecular dynamics simulations to obtain the time evolution of water molecules and the effect of H₂O on the mechanisms of CL-20 at high temperatures. It was determined that the initial decomposition mechanisms of CL-20 are not dependent on the presence of water, but the secondary reaction pathways are. At low temperatures (T<1500 K), there is no relationship between the H₂O, hydrate CL-20, and pure CL-20 systems, as the mechanism is only the dissociation of the N―NO₂ bond to form the NO₂ radical. At high temperatures (1500 K≤T≤2500 K), water molecules act as a reactant or form catalytic systems with NO₂ radical to form OH radical, leading to the formation of O₂, H₂O₂, and other products. Water molecules accelerate the secondary stage reaction of hydrate systems, leading to increased secondary reaction rates and number of NO₂ radicals in the CL-20 hydrate compared with the pure CL-20 system. At very high temperatures (T>2500 K), the dissociation of water molecules competes with the initial thermal decomposition pathway of CL-20, leading to a larger rate constant for the pure CL-20 than for the hydrate CL-20.

A chemical kinetic model consisting of 103 species and 395 elementary reactions has been developed. This kinetic model well describes the formation of polycyclic aromatic hydrocarbons (PAHs) for multi-component gasoline surrogate fuels. Model validation results showed that the predicted PAHs and aromatic precursors using this chemical mechanism were consistent with the experimental results in the premixed flame of ethylene, toluene, n-heptane, and the opposed flow flame of n-heptane. The mechanism is not yet applicable to multidimensional computational fluid dynamics simulations for PAH formation of gasoline combustion. However, compared with the existing kinetic model, the present kinetic model contains fewer species and reactions, so it is closer to the aim of a model for practical applications.

The mechanism and kinetics of unimolecular decomposition of CH₃SO₃ are studied at the G3XMP2//B3LYP/6-311+G(3df,2p) level of theory. Six possible dissociation channels and potential energy surface for the CH₃SO₃ decomposition are investigated. Rate constants over the temperature range of 200-3000 K are calculated using Rice-Ramsperger-Kassel-Marcus (RRKM) theory. The results indicate that the product P1(CH₃+SO₃) is dominant between 200-3000 K. Products P2(CH₃O+SO₂) and P3(HCHO+HOSO) increase significantly at higher temperatures (>3000 K). Products P4(CHSO₂+H₂O), P5(CH₂SO₃+H) and P6(CHSO₃+H₂) show little formation in the temperature range (200-3000 K). The total rate constant can be expressed as k_total=1.40×10¹²T^0.15exp(7831.58/T). Thermodynamic properties including enthalpies of formation (D_fH^Θ_{298 K}, D_fH_{0 K}), entropies (S^Θ_{298 K}), and heat capacities (C_p, 298-2000 K) of all the minima and transition states are predicted from statistical mechanics, and found to be in od agreement with the available experimental values.

Gd₂Zr₂O₇ is a well known host for nuclear waste immobilization because of the high neutron absorption cross section of Gd and low energy transformation between ordered pyrochlore and disordered defect-fluorite structures. Pyrochlore Gd₂Zr₂O₇ was synthesized at relatively low temperature (compared with traditional high temperature solid-state reaction) using Gd(NO₃)₃·nH₂O, Zr(NO₃)₄·nH₂O as a starting material and a small amount of NaF as fluxing agent. Ce⁴⁺ was used as an analogue for Pu⁴⁺ and its immobilization behavior in Gd₂Zr₂O₇ was studied in a series of solidified forms comprising (Gd_1-xCe_x)₂Zr₂O_7+x (0≤x≤0.6). Powder X-ray diffraction (XRD) data showed that the sample structure transformed from pyrochlore to defect-fluorite type with increasing x but maintained constant unit cell volumes. As x was increased to 0.6, the diffraction peaks showed broadening, suggesting considerable lattice distortion. When x=1, i.e., all Gd³⁺ are placed by Ce⁴⁺, the product was not Ce₂Zr₂O₈, but a phase separated mixture of tetra nal (Zr_0.88Ce_0.12)O₂ and an ideal fluorite (Ce_0.75Zr_0.25)O₂. Leach rate measurements indicated that the leach rate of Gd³⁺, Zr⁴⁺, Ce⁴⁺ was low when x≤0.2, but increased significantly when x≥0.4. This suggests that the substitution rate of Pu⁴⁺ for Gd³⁺ should not be more than 40% when Gd₂Zr₂O₇ used as the host matrix for Pu⁴⁺.

Exploring the binding features between small drug molecules and biomolecules is particularly important because it can provide valuable information for understanding the interaction mechanism and therefore rationally designing, modifying and screening of new drugs. In this paper, the site-preference of the nucleic acid bases uracil and thymine hydrogen bonding to the small medical molecule quercetin is investigated using the density functional theory method. Thirty stable hydrogen-bonded complexes were located at the B3LYP/6-31G(d) level of theory. The binding energies for these complexes were further evaluated at the B3LYP/6-311++G(3df,2p) level of theory with the basis set superposition error corrections. The results indicate that quercetin can interact with uracil or thymine through five binding sites, which herein we refer to as Site qu1, Site qu2, Site qu3, Site qu4, and Site qu5, and uracil (or thymine) can interact with quercetin through three binding sites, which herein we refer to as Site u1, Site u2, and Site u3 (or Site t1, Site t2, and Site t3). We found that once the binding site of quercetin is fixed, the hydrogen bonds formed through uracil Site u1 and thymine Site t1 are the strongest, while those formed through uracil Site u2 and thymine Site t2 are the weakest. When the binding site of uracil or thymine is fixed, the hydrogen bonds formed through the quercetin Site qu1 are the strongest, followed by those formed through quercetin Site qu5, while those formed through quercetin Site qu3 are the weakest. Atoms in molecules (AIM) and natural bond orbital (NBO) analyses were also carried out to explore the interaction nature of these hydrogen-bonded complexes.

A pair of chiral o-iminobenzosemiquinonato Fe(III) complexes, Λ-mer- [Fe(L^ISQ)₃] and Δ-mer-[Fe(L^ISQ)₃] (L^ISQ: 2-phenylimino-4, 6-di-tert-butylphenol, mer: meridian configuration), were synthesized from 2-anilino-4,6-di-tert-butylphenol (H₂L) and FeCl₂·4H₂O. Their absolute configurations were determined by single crystal X-ray diffraction (XRD) and solid-state circular dichroism (CD) spectra (the same single crystal for XRD was dispersed in KCl). Correlations between the absolute configurations of the chiral-atmetal o-iminobenzosemiquinonato M(III) complexes [M(L^ISQ)₃] (M=Cr, Fe, Co) and their solid-state CD spectra were also established. Comparison between solid-state CD spectra of the bulk samples from 10 different syntheses and their single crystals were thoroughly analyzed. The solid-state CD spectra of the powdered samples from 10 different crystallizations of one product were characterized. These studies indicated that mirror symmetry breaking (MSB) occurred during the crystallization process of the Fe(III) complexes and their enantiomeric excess (ee) values were between 15% and 100%.

Hologram quantitative structure-activity relationship (HQSAR) analysis was conducted on a series of benzimidazole compounds to build the HQSAR model between corrosion inhibition properties and molecular structures in acid environment. The optimal HQSAR model was determined by investigating the influence of different fragment distinction and fragment size on the models, and the models’ stability and predictive ability were evaluated. The results show that the optimal HQSAR model was generated using atoms(A), bonds(B), connectivity(C), hydrogen(H), chirality(Ch), donor and acceptor(D&A) as fragment distinction and fragment size of 1-3. The model had a non-cross validated coefficient (r²) value of 0.996, a cross-validated (q²) value of 0.960, and a cross-validated standard error (SE_cv) value of 3.709, which indicates od statistics stability and predictive power. On the basis of the maps derived from the optimal HQSAR model, 38 new benzimidazole derivatives were designed and screened using the optimal HQSAR model, giving potential candidates with high predictive inhibition efficiency. This work provides valuable information for further research and design of more promising corrosion inhibitors in the oil and gas field.

Coarse-grained models with different ratios of numbers of hydrophilic particles to hydrophobic particles were built for amphiphilic random copolymers. The surface hydrophilicity of spherical micelles formed from self-assembly of amphiphilic random copolymers in solution was investigated via dissipative particle dynamics (DPD) simulations. The simulations showed that solid spherical micelles are formed from self-assembly of amphiphilic random copolymers in selective solvents. The surface hydrophilicity of spherical micelles is related to the content of hydrophilic particles and selectivity of the solvent. The surface hydrophilicity of spherical micelles increases with increasing content of hydrophilic particles. In addition, the surface hydrophilicity of spherical micelles increases with the increase of the repulsion parameters between hydrophobic particles and solvent, which is in od agreement with the experimental results. These findings can provide theoretical guidance for molecular design and experimental studies on selfassembly of amphiphilic random copolymers in solution.

The ion equilibrium at the interface of solution within compacted bentonite, and the external solution is an important factor influencing the diffusion of ionic species in the compacted bentonite. The ion equilibrium can be calculated by the Donnan model using macroscopic compacted bentonite parameters. By constructing a single pore type structure model for compacted bentonite, where the montmorillonite TOT-layers are depicted as a parallel array of rectangles, the ion equilibrium can also be calculated by the Poisson-Boltzmann (PB) model with a scale-defining variable H. We demonstrated that the ion equilibrium coefficients calculated by the PB model are always larger than those calculated by the Donnan model, and the models are linked by the factor H. The mathematical transition from the PB model to the Donnan model occurs in the limiting case H→0. The application of the two models to diffusion problem is also discussed, and the PB model is shown to be more realistic and suitable for solving actual diffusion problems.

A density functional theory (DFT) and wave function theory investigation on the structures and electronic properties of B₂Au₂^0/-/2- clusters has been performed. Both the doublet B₂Au^2- ([Au-B B-Au]^-) (C_2h, ²A_u) and the singlet B₂Au₂^2- ([Au-B≡B-Au]^2-) (C_2h, ¹A_g) have distorted linear ground-state structures containing a multiply bonded BB core (B B or B≡B) terminated by two Au atoms, while neutral B₂Au₂ ([Au-B＝B-Au]) (D_∞h, ³Σ_g^-) has a perfect linear geometry. One-electron detachment energies and symmetrical stretching vibrational frequencies were calculated for C_2h B₂Au^2- facilitate their future characterizations. A neutral salt of B₂Au₂Li₂ with an elusive B≡B triple bond is predicted, which is a possible target for experiments. The high stability of B₂Au₂^2- suggests that it may exist as a viable building block in the condensed phase.

As potential molecular wire species, the geometrical and electronic structures of metal string complexes M₃(dpa)₄Cl₂ (1: M=Co, 2: M=Rh, 3: M=Ir; dpa=dipyridylamide) were investigated theoretically using density functional theory with the PBE0 functional by considering the interaction of an external electric field along the M₃⁶⁺ linear metal chain. The results show that the ground states of the complexes are all doublets. There is a 3-center-3-electron σ bond delocalized over the M₃⁶⁺ chain for 1 and 2, while there is a 3-center-4-electron σ bond and a weak δ bond among the Ir₃⁶⁺ chain in 3. Moving down the column of Co, Rh, and Ir elements in the periodic table, the complexes with the corresponding metals showed some regular trends, such as stronger M－M bonds, smaller LUMO-HOMO gaps, weaker anti-ferromagnetic spin coupling among the M₃⁶⁺ chains, and stronger spin delocalization from M₃⁶⁺ to ligands. In the external electric field along the Cl4→Cl5 direction, the M3 ― Cl5 bonds at the low potential side tend to be shortened, while the M2―Cl4 distances at the high potential side increase. With the increase of electric field, the average M―M distances slightly decrease, which is beneficial for electron transport. When the electric field increases, the molecular energy decreases and the dipole moment linearly increases. Moreover, the negative charge moves from Cl5 at the low potential end towards Cl4 at the high potential end, and the spin electron moves from M3 at the low potential end to M1 and M2 at the high potential end, while the positive charges transfer in the opposite direction along the M₃⁶⁺ chain of 3. However, there is no charge transfer between dpa^- ligands and M₃⁶⁺ chain or Cl^- ligands. The LUMO-HOMO gaps decrease with increasing electric field, which is beneficial for electron transfer. The sensitivity of the frontier orbitals to the electric field is different, which leads to the orbital level crossing for LUMO or HOMO. Moving down the column of metal elements in the periodic table, the complexes with the corresponding metals showed weaker orbital level crossing for LUMO or HOMO and smaller deviation of average M―M distances due to the effect of the electric field.

The double-proton-transfer reaction of the isolated guanine-cytosine (GC) base pair and four DNA trimers with different nucleobase sequences (dATGCAT, dGCGCGC, dTAGCTA, and dCGGCCG) are studied by quantum mechanical calculations using ONIOM(M06-2X/6-31G^*:PM3). Proton-transfer patterns, energy and structural properties are analyzed to gain insight into the double-proton-transfer mechanism with consideration to environmental factors. In the gas phase, a stepwise mechanism is found for the dCGGCCG trimer, and a concerted mechanism is found in the other four models. The computational results demonstrate that electrostatic interaction of the peripheral and middle base pairs have a pronounced effect on double-proton-transfer pattern of GC base pairs. The structures with dATGCAT and dGCGCGC sequences facilitate H4a proton transfer and those with dTAGCTA and dCGGCCG sequence facilitate H1 proton transfer. The high proton affinity of cytosine at N3 facilitates H1 proton transfer. In aqueous solution, electrostatic interactions are reduced and the products of single-proton-transfer in the stepwise mechanism are stabilized. This results in a stepwise transfer pattern becoming favorable. Solvent effects favor the single-proton-transfer reaction more than gas phase conditions, but increase the reaction energy of double-proton-transfer.

CdSe/ZnS core/shell quantum dots (QDs) were synthesized and adsorbed onto nanocrystalline TiO₂ films for application in quantum dot sensitized solar cells(QDSSCs). Femtosecond transient absorption spectra was measured to investigate the effect of the ZnS shell coating on electron injection from CdSe QDs to nanocrystalline TiO₂ films. The results showed a decrease in electron injection rate from 7.14×10¹¹s^-1 to 2.38×10^-11s^-1 after ZnS shell coating, which means the electron injection rate only remained 1/3. The fill factor(FF) and stability of QDSSCs were improved by ZnS coating, but the photocurrent decreased, resulting in an overall decrease in efficiency. The slower electron injection rate is found to be the main cause for this decrease in photocurrent and efficiency, which matches well with the photovoltaic property test. These results provide information for optimizing the current and efficiency of QDSSCs employing core/shell QDs.

The composite of ordered mesoporous carbon (CMK-3) and Li₄Ti₅O₁₂ (Li₄Ti₅O₁₂/CMK-3) was prepared by the wet impregnation of CMK-3 with LiNO₃ and Ti(OC₄H₉)₄ solution followed by calcination. Its morphology and structure were examined using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The content of Li₄Ti₅O₁₂ in the mesoporous nanocomposite was determined by thermogravimetric analysis. Its electrochemical performance as the negative electrode material of lithium-ion batteries was investigated by galvanostatic charge-discharge tests, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The results show that Li₄Ti₅O₁₂ is formed inside the mesopore channels of CMK-3 and some particles are located on the surface of CMK-3. The composite shows significantly greater high-rate performance than commercial Li₄Ti₅O₁₂. The specific capacity of Li₄Ti₅O₁₂ in the composite is higher than Li₄Ti₅O₁₂ without CMK-3 (117.8 mAh·g^-1 at 1C rate), and its stabilized specific capacity reached 160, 143, and 131 mAh·g^-1 at 0.5C, 1C, and 5C charge-discharge rates, respectively, with a columbic efficiency of nearly 100%. The capacity loss after 100 cycles at 5C rate was less than 0.62%. This result clearly indicates that CMK-3 improves the high rate performance of Li₄Ti₅O₁₂, likely by reducing the particle size of Li₄Ti₅O₁₂ and increasing its electronic conductivity owing to the unique structure and od electronic conduction nature of CMK-3.

Three poly(propylene oxide)-poly(ethylene oxide) branched block polyethers containing a benzene ring moiety were synthesized, with different molecular weights and propylene oxide/ethylene oxide (PPO/PEO) compositions. Their aggregation behaviors at air/water and oil/water interfaces were investigated by interfacial tension, surface pressure and interfacial dilational rheology methods. Aggregation and the emulsion breaking properties (demulsification) for crude oil were studied based on the polymer PEO content and molecular weight. The demulsification performance of these polyethers and their crosslinked counterparts were compared at different temperatures. The results showed that a polyether with a higher proportion of PEO groups and larger molecular weight occupied a larger area at the air/water interface, reached equilibrium faster, and featured a larger dilational modulus at the oil/water interface. However, the demulsification experiments showed that the polyether with a moderate level of PEO content gave better performance. The cross linking method did not improve demulsification ability in the polyether with large molecular weights. Temperature was also found to have no explicit influence on the demulsification of the cross linked polyethers. This study provides useful data for the selection and application of chemicals used in processing of crude oil.

The effective surface charge of colloidal particles is an important parameter for calculating inter-particle interaction potentials. In this study, we investigated the effective charge of seven kinds of polystyrene particles having different diameters and surface charges. Two methods, conductivity-number density relationships and conductometric titration, were used to measure the effective charges. The results obtained from the two different methods show small variations of 7%. The effective charges were also calculated from empirical formulas and found to be twice as large as the experimental values, indicating these formulas cannot be universally applied to all colloidal dispersions.

Mesocellular silica foam (MCF) was prepared using P123 (EO₂₀-PO₇₀-EO₂₀) as template and then functionalized with pentaethylenehexamine (PEHA) for CO₂ adsorption. The samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorptiondesorption isotherms, Fourier transform infrared (FTIR) spectroscopy and thermal gravimetric analysis (TGA). These results indicated that after modification with PEHA, the structure of the support itself was undamaged. The highest CO₂ adsorption capacity of MCF-PEHA was obtained at 75℃. With increasing PEHA loading, the CO₂ adsorption capacity increases and approached the highest adsorption capacity (3.55 mmol·g^-1) with a 70% (w) PEHA loading. Moisture improved the CO₂ adsorption performance of the adsorbents. Repeated adsorption-desorption cycling indicated that the sorbents maintained stable CO₂ adsorption capacity after 4 cycles, indicating potential for regeneration of the adsorbents.

The surface acidity of Y-type zeolites (HY and NaY) modified by solid state ion exchange (SSIE) and liquid phase ion exchange were characterized by in situ Fourier transform infrared (FTIR) spectroscopy using pyridine as the probe molecule (Py-FTIR). The adsorption of single probe molecules (thiophene, cyclohexene and benzene) and double probe molecules (thiophene and cyclohexene, thiophene and benzene) compared with sorbents were studied using in situ FTIR spectroscopy. The results indicated that the Brönsted acid (B acid) of HY (L-CeY) is the catalytic center of cyclohexene dimerized alkenyl carbenium ions and thiophene oli merization, while the Lewis acid (L acid) is the major center of adsorption of thiophene, cyclohexene, and benzene. In addition, there is strong chemisorption and competitive adsorption of cyclohexene and thiophene, which provides evidence for the poor performance of removing sulfur. The S-CeY zeolite has abundant of weak Lewis acid sites. The sorbent is od at absorbing thiophene, while the influence of the competition adsorption of cyclohexene was not predominately. As to NaY zeolite, there is no preference for adsorption of thiophene, cyclohexene and benzene.

Relationship between aromatics distribution, in the process of methanol to aromatics (MTA), and the conversion of methanol and the catalyst acidity was investigated over a series of Zn/P/ZSM-5 catalysts with different Si/Al molar ratios and zinc loading. To understand the contribution of aromatization, isomerization, dealkylation and alkylation reactivity of the catalyst to the aromatics distribution, coke deposition degree of Zn/P/ZSM-5 catalyst was tailored as using different feedstocks including methanol, xylene or the mixture of methanol and toluene. With the coke deposition, the amount of different types of acidic sites of catalyst varied significantly, characterized by NH₃-temperature programmed desorption (NH3-TPD) and pyridine-infrared methods. Aromatization, dealkylation, alkylation, and isomerization showed sensitivity to a reduction in the density of strongly acidic sites. Dealkylation reaction was preferentially inhibited just by slightly decreasing the density of strong acid sites. However, aromatization and isomerization reaction were inhibited only when the density of strong acid sites was significantly decreased. In all cases, alkylation was found to be uninfluenced by acidic site density. A Zn/P/ZSM-5 catalyst with Si/Al molar ratio of 14 and 3% (w) Zn loading exhibited aromatics yields of 75% and xylene yields of about 35%, indicating potential for industrial application.

A series of Co-mordenite (MOR) catalysts prepared by ion-exchange or impregnation methods were used in the selective catalytic reaction of NO with methane (CH₄-SCR). The structure and physicochemical properties of the catalysts were examined by X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), UV-Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and temperature-programmed desorption of NO (NO-TPD). The Co species in the catalyst prepared by impregnation is present as Co₃O₄, whereas in the catalyst prepared by an ion-exchange method, the Co species enter in the mordenite skeleton with the ion form, and the more Co²⁺ and [Co-O-Co]²⁺ formed in the catalysts, the more uniform the adsorption of NO centers and the active centers of CH₄-SCR. The catalysts prepared by different methods exhibited different activities for CH₄-SCR. The catalysts prepared by ion-exchange exhibited activity over a wide activity temperature region, and NO conversion was over 50% at 327-450℃ on the Co(0.30)-MOR catalyst.

Nitrogen-doped hollow carbon microspheres (N-HCMS) were synthesized by carbonization of poly(dopamine). Platinum (Pt) nanoparticles (NPs) were deposited onto the N-HCMS via a microwaveassisted reduction process. The morphology, surface area, and pore size distribution of the N-HCMS supported Pt catalysts (Pt/N-HCMS) were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and surface area and porosimetry measurements. The electrocatalytic properties of the Pt/N-HCMS catalyst towards oxygen-reduction reaction were investigated by cyclic voltammetry and linear sweep voltammetry. The Pt/N-HCMS catalyst showed almost double the specific mass activity of a commercial carbon supported Pt catalyst. This was attributed to a uniform dispersion of the Pt NPs and the unique mesoporous and hollow structure of N-HCMS. In addition, fast electron transfer processes were found to occur on the nitrogen doped N-HCMS and the catalyst exhibited excellent long-term stability. This work is of significance for the development of high-performance cathodic catalysts in fuel cells.

Pure TiO₂ and Sn⁴⁺ doped TiO₂ (TiO₂-Snx%) photocatalysts were prepared by a sol-gel method, where x% represents the nominal molar fraction of Sn⁴⁺ ions in the Zr⁴⁺ structure. The crystal structure and energy band structure of the resultant catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and surface photovoltage spectroscopy (SPS).The results show that for a low content of Sn⁴⁺ ions, the Sn⁴⁺ ions are doped into the TiO₂ lattice and replace lattice Ti⁴⁺ ions in a substitute mode (Ti_1-xSn_xO₂). The energy levels of these Sn⁴⁺ ions are located 0.38 eV below the conduction band. Moreover, the rutile SnO₂ crystal structure evolves with increasing content of Sn⁴⁺ ions, i.e., a TiO₂/SnO₂ structure is formed. The conduction band of SnO₂ is located 0.33 eV lower than that of TiO₂. The separation and recombination mechanism of the photo-generated carriers was characterized by photoluminescence and transient photovoltage techniques. The results showed that the formation of the energy levels of Sn⁴⁺ ions and the conduction band of rutile SnO₂ can enhance the separation of the photogenerated carriers, and suppress the recombination of photo-generated carriers. However, the energy levels of Sn⁴⁺ can lead to a much longer life time and higher separation efficiency of the photo-generated carriers. For different content of Sn⁴⁺ in Sn⁴⁺ ion doped TiO₂(TiO₂-Snx%), the abovementioned aspects improve the photocatalytic activity.

To improve the solar energy transformation efficiency, it is necessary to study the efficiency of photocatalysts under visible light irradiation. In this study, the composite photocatalyst NiS-PdS/CdS has been developed using a hydrothermal method from the raw materials cadmium sulfide, palladium chloride, nickel acetate and thiourea. The characteristics of NiS-PdS/CdS were studied by X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (DRS), transmission electron microscopy (TEM), and photoluminescence (PL) spectroscopy. In addition, the photocatalytic activities for water splitting were tested using lactic acid as the sacrificial reagent. The results showed that NiS and PdS dispersed well on the surface of CdS. The activity of NiS-PdS/CdS was much higher than that of CdS under visible light irradiation. When the loading amount of NiS and PdS reached 1.5% and 0.41% (w), respectively, NiS-PdS/ CdS showed the highest activity. The H₂ evolution rate increased up to 6556 μmol·h^-1, which was six times higher than that of unloaded CdS and nearly two times higher than that of NiS/CdS. The apparent quantum yield was 47.5% (λ=420 nm). The co-catalysts NiS and PdS prompted the transfer of photogenerated electrons and holes, respectively. Compared with single-loading, co-loading the two co-catalysts could transfer and separate charge carriers more efficiently, resulting in enhancement of the activity for photocatalytic hydrogen production.

A series of Sr-Zr-Ti (SZT) mixed oxide catalysts were prepared by a fractional-precipitation method. These photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and ultraviolet visible (UV-Vis) diffuse reflectance absorption spectra. Photocatalytic degradation of methylene blue was investigated to determine the photoactivity of the catalyst. It was shown that with a Zr/Ti ratio<1, the SZT mixed oxide catalysts showed improved photocatalytic activity. This was attributed to lattice defects creating active photocatalytic sites because of Zr⁴⁺ doping. For Zr/Ti ratios ≥1, the catalysts showed markedly improved photocatalytic activity because of new crystalline phases of SrZrO₃ and Ti_nO_2n-1 (n=4, 9)that facilitated splitting and conduction for electron/hole. Typical SZT samples (Zr/Ti=4) showed the highest photocatalytic activity, with first-order reaction rate constant 13.5 times that of a SrTiO₃ sample.

Carbon nanotubes (CNTs) have been ultrasonically treated with the mixed acid (H₂SO₄/HNO₃, 3:1, volume ratio), embedding the active －COOH groups onto the surface of the CNTs. As a result, the acid-treated CNTs serve as chemical reactors for subsequent grafting of L-lysine or octadecylamine (ODA). It was revealed that L-lysine and ODA covalently bond to the surface of the oxidized CNTs through amidation of carboxylic acid groups (CNTs-COOH) and lysine or ODA via intermediate acyl chlorides (CNTs-COCl). The hydrophilic and lipophilic CNTs have high aquatic and ethanol solubility, and the solubility of the surface modified CNTs in water and ethanol were measured to be as high as 6.85 and 10.15 mg·mL^-1, respectively. The surface nature of modified CNTs and the properties of TiO₂-CNTs composite photocatalysts, which were prepared through sol-gel or low temperature hydrothermal synthesis, were investigated by Fourier transform infrared (FTIR), laser Raman, X-ray diffraction (XRD), Brunauer-Emmett-Teller N2 adsorption, transmission electron microscopy (TEM), and X-ray photoelectron spectrum (XPS). Improved photocatalytic performance was observed for TiO₂ coupled by hydrophilic or lipophilic CNT, which were obtained by low temperature hydrothermal and sol-gel synthesis, respectively, and it was revealed that there is an affinity between the photocatalytic performance of TiO₂-CNTs hybrids and the dispersibility of CNTs. It is proposed that the improved photocatalytic activity of CNT-TiO₂ compared with pure TiO₂ photocatalysts can be mainly attributed to the homogeneous and dense dispersion of TiO₂ on the modified CNTs and the intimate contact between TiO₂ and CNTs, which results in dense heterojunctions at the interface of TiO₂ and CNTs through the Ti－O－C structure.

To explore the important factors affecting the stability of gas phase bradykinin (R¹P²P³G⁴F⁵S⁶P⁷F⁸R⁹), the non-covalent interactions between fragment peptides of bradykinin were investigated by electrospray ionization mass spectrometry (ESI-MS). The fracture sites are S6P7 (mode 1) and F5S6 (mode 2). The fragment peptides of bradykinin and its des-arginine analogues were synthesized. ESI-MS results showed that the fragment peptides of bradykinin obtained in the two modes can easily react by non-covalent interactions. In fracture mode 1, when R⁹ was removed, the peptide PF seldom bound to any other fragment peptide. While in fracture mode 2, non-covalent binding still occurred between fragment peptides when either R1 or R9 was removed, which indicates that serine is likely to be at the position of the β-turn. The collision induced dissociation (CID) revealed that the binding strength between RPPGFS and PFR, or RPPGF and SPFR, is stronger than for the peptides without R. For the complexes of RPPGFS with PFR, and RPPGF with SPFR, the binding constant (K_st) values determined by mass spectrometric titrations were 3.53×10³ and 3.16×10³, respectively, which are greater than the K_st value (1.25×10³) of the complexes of PPGF with SPF. The mass spectrometric titrations confirmed the results from CID, indicating that the hydrogen bonds between the arginine residues of the two terminals of bradykinin play an important role in stabilizing the conformation of gas phase bradykinin.

Partially reduced graphene oxide/titanium dioxide (R /TiO₂) composite was synthesized using tetrabutyl titanate and graphite oxide by a hydrothermal method. Photocatalytic activity of the material was evaluated by the degradation of methylene blue solution under visible light and UV light. The results suggest that the crystal phase and dispersion of titanium oxide in the composite can be controlled by varying the reaction temperature and amount of graphite oxide. Graphene oxide was partially reduced in the hydrothermal reaction process. Photocatalytic activities of partially reduced graphene oxide/titanium dioxide composites under both visible and UV light irradiation were higher than those of pure TiO₂. Partially reduced graphene oxide may act as a support and electron acceptor, and can also extend and enhance the band edge absorption of TiO₂ into the visible light region, hence effectively enhancing the adsorbability and photocatalytic activity of TiO₂.

A new phosphorescent host material based on 9-[6-(9H-carbazol-9-yl)hexyl]-9H-carbazole (hCP) was designed and synthesized and its structure and properties were characterized. These investigations indicated that hCP possessed a twisted rigid structure, with the two carbazole units in a non-coplanar conformation leading to a higher triplet energy level (3.01 eV). hCP also possessed a high glass transition temperature (93℃). Electroluminescent devices were fabricated by doping the hCP host with the green- phosphorescent fac-tris(2-phenylpyridine)iridium(III) (Ir(ppy)₃) as the light-emitting layer. Compared with devices employing the typical (4,4'-N,N'-dicarbazole)biphenyl) (CBP) as a host, the hCP host showed a 34.8% increase of current efficiency to 15.1 cd·A^-1.

Calcium and barium zirconate powders based upon CaZrO₃:Eu³⁺,A and BaZrO₃:Eu³⁺,A (A=Li⁺, Na⁺, K⁺) were prepared by combustion synthesis method and heating to ~1000℃ to improve crystallinity. The structure and morphology of materials were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD results showed that CaZrO₃:Eu³⁺,A and BaZrO₃:Eu³⁺,A (A=Li⁺, Na⁺, K⁺) perovskites possessed orthorhombic and cubic structures, respectively. The morphologies of all powders were very similar consisting of small, coagulated, cubical particles with narrow size distributions and smooth and regular surfaces. The characteristic luminescences of Eu³⁺ ions in CaZrO₃:Eu³⁺,A (A=Li⁺, Na⁺, K⁺) lattices were present with strong emissions at 614 and 625 nm for ⁵D₀→⁷F₂ transitions with other weaker emissions observed at 575, 592, 655, and 701 nm corresponding to ⁵D₀→⁷F_n transitions (where n=0, 1, 3, 4 respectively). In BaZrO₃:Eu³⁺ both the ⁵D₀→⁷F₁ and ⁵D₀→⁷F₂ transitions at 595 and 613 nm were strong. Photoluminescence intensities of CaZrO₃:Eu³⁺ samples were higher than those of BaZrO₃:Eu³⁺ lattices. This remarkable increase of photoluminescence intensity (corresponding to ⁵D₀→⁷F_n transitions) was observed in CaZrO₃:Eu³⁺ and BaZrO₃:Eu³⁺ if co-doped with Li⁺ ions. An additional broad band composed of many peaks between 440 to 575 nm was observed in BaZrO₃:Eu³⁺,,A samples. The intensity of this band was greatest in Li⁺ co-doped samples and lowest for K⁺ doped samples.