The bimolecular rate constants for the gas- phase reactions of C₂(a³П_u) with sulfur-bearing molecules (H₂S, SO₂, CS₂) were measured over the temperature range 298-673 K, by means of pulsed laser photolysis/laser-induced fluorescence technique. The rate constants (cm³·molecule^-1·s^-1) can be fitted by the normal Arrhenius expressions: k(H₂S)=(1.61±0.06)×10^-12exp[-(180.91±15.73)/T], k(SO₂)=(1.26±0.10)×10^-15 exp[(2230.68±27.77)/T], k(CS₂)=(1.17±0.02)×10^-10 exp[(253.31±7.69)/T], where all error estimates are ±2σ and represent the precision of the fit. The observed bimolecular rate constants and positive temperature dependence of k(H₂S) show that the reaction of C₂(a³П_u) with H₂S in the range 298-673 K proceeds via a hydrogen-abstraction mechanism. The bimolecular rate constants for the reaction of C₂(a³П_u) with SO₂ show a strong negative temperature dependence. The high rate constants for the C₂(a³П_u)+CS₂ reaction and negative temperature dependence support an addition mechanism.

The aim of this study was to construct a quantitative structure-property relationship model to identify relationships between the molecular structures and viscosities of 310 compounds, as well as specific structural factors that could affect the viscosities of the compounds. Using an iterative self-organizing data analysis technique, the sample set was preliminarily classified into two sets, including a training set and a test set. The molecular structure descriptors of 310 compounds were calculated using version 2.1 of the Dra n software and subsequently sifted using an ant colony al rithm (ACO), which resulted in the selection of five parameters. Multiple linear regression (MLR) and the support vector machine (SVM) techniques were then used to establish ACO-MLR and ACO-SVMmodels, respectively. The results showed that the performance of the non-linear ACOSVMmodel (correlation coefficient R_train²=0.9013, R_test²=0.9026) was superior to the linearACO-MLRmodel (R_train²=0.7680, R_test²=0.8725). The correlation coefficients between the experimental and predicted values of the ACOMLR and ACO-SVM models for the test set were 0.934 and 0.950, respectively. The predictive properties of the two models were therefore determined to be satisfying. The application domain of the model was also studied using a Williams graph, which demonstrated that the models established in this study provide effective methods for predicting the viscosities of specific compounds based on their molecular structure.

Surfactants can be adsorbed with extracellular polymeric substances (EPS) to form micelles with the release of both free and bound water molecules, and this process could be used to improve the performance of the sludge dewatering process. In this paper, coarse-grained molecular dynamics (MD) simulations were adopted to study the formation and structure of complexes resulting from the mixing of a Gemini surfactant and EPS. The hydrophobic or hydrophilic performance of the polyelectrolyte had a significant impact on the adsorption process. The main driving force for adsorption between the hydrophilic polyelectrolyte and the Gemini surfactant was electrostatic attraction, where the head group of the Gemini surfactant was adsorbed onto the chain with the tail chain pointing towards the solvent. The adsorption process between the hydrophobic polyelectrolyte and the Gemini surfactant was influenced by both electrostatic and hydrophobic effects, with the Gemini surfactant being oriented parallel to the configuration of the polyelectrolyte chain. The coupling group length of the Gemini surfactant had very little influence on the adsorption process. Variations in the charge density of the polyelectrolyte chain aided the adsorption of the hydrophilic polyelectrolyte, but had no impact on the adsorption of the hydrophobic polyelectrolyte.

The mechanism of the Ni-catalyzed reductive cross-coupling reaction of bromobenzene (R₁) and methyl 4-bromobenzoate (R₂) to form an unsymmetrical biaryl system has been theoretically investigated using density functional theory calculations. Our results showed that the Ni⁰-catalyzed process was favored over the NiI-catalyzed mechanism. The mechanism for the reaction of the Ni⁰ catalyst initially attacking either R₁ or R₂ was quite similar, where the energy barrier in the gas phase for the rate-limiting step was 70.50 or 49.66 kJ·mol^-1, respectively. The mechanism in the favored Ni⁰-catalyzed reaction involved the following steps: first oxidative addition, reduction, second oxidative addition, reductive elimination, and catalyst regeneration. Our calculated results also indicated that no organometallic reagents were produced in the reaction cycle.

The adsorption behavior of Pb(OH)⁺ on the basal octahedral (001) surface of kaolinite has been investigated using the Perdew-Burke-Ernzerhof generalized gradient approximation (GGA-PBE) of density functional theory with periodic slab models, where the water environment was considered. The coordination geometry, coordination number, preferred adsorption position, and adsorption type were examined, with binding energy estimated. All the monodentate and bidentate complexes exhibited hemi- directed geometry with coordination numbers of 3-5. Site of "Ou" with "up" hydrogen was more favorable for monodentate complex than site of "O_l" with "lying" hydrogen. Monodentate complexation of "O_u" site with a high binding energy of -182.60 kJ·mol^-1 should be the most preferred adsorption mode, while bidentate complexation on "O_uO_l" site of single Al center was also probable. The stability of adsorption complex was found closely related to the hydrogen bonding interactions between surface O_l and H in aqua ligands of Pb(Ⅱ). Mulliken population and density of states analyses showed that coupling of Pb 6p with the antibonding Pb 6s―O 2p states was the primary orbital interaction between Pb(Ⅱ) and the surface oxygen. Hydrogen complexation occupied a much large proportion in the joint coordination structure of bidentate complex, where bonding state filling predominated for the Pb―O_l interaction.

The influence of molecular rotation, laser pulse shape and initial phase on controlling the infrared multiphoton excitation of diatomic molecules has been studied using an analytical algebraic approach, which involved the derivation of analytic transition probabilities with various rotational channels. To observe the correctional functions of the rotational energy and the relationship between the molecular orientation and the polarized direction of the laser field in terms of their impact on controlling multiphoton excitation, we calculated the probabilities in the purely vibrational and ro-vibrational cases. The maximumtransition probabilities were determined as a function of the time and molecular orientation angle in both cases for comparison, which allowed for the target multiphoton excitations to be achieved. However, oscillations appeared in the population of the ro-vibrational case which denoted rotational interference can decrease the selectivity of the molecular vibrational excitation. Furthermore, the rotational energy had a corrected action on multiphoton non-resonant excitation and the power of actions was dependent on the molecular anharmonicity. We have also provided a discussion of the influences of laser pulse shape and initial phase. We found that the use of an appropriate laser pluse shape afforded the target multiphoton excitation event, and that the initial phase of the chirped laser pulse had an obvious modulatory function on the multiphoton processes.

In this study, we performed a first-principles investigation of the rules verning changes in the electronic structure, band structure, optical properties, elastic properties, and anisotropy of an α-S₈ photocatalyst after carbon doping. It was shown that the bond length decreased, and the bond overlap population and charge density increased, with the formation of new C―S bonds, after doping. This indicated that the new bonds had enhanced covalence. The energy band gap of the doped structure was 2.64 eV, which is 0.15 eV lower than that of pure α-S₈, showing that doping increased the conductivity of α-S₈. The optical absorption spectrum of the doped system was extended to 650 nm, showing that the light absorption efficiency of α-S₈ was greatly enhanced. Calculations of the elastic properties showed that the mechanical capacity of carbon-doped α-S₈ decreased, but it remained brittle. The doped material had higher anisotropy.

The ground and excited states, charge- transport, and fluorescence properties of a series of polymers based on benzothiadiazole and silafluorene were investigated using density functional theory (DFT). The band gaps, ionization potentials, electron affinities, the lowest excitation energies, and absorption spectra of the polymers were estimated by extrapolating those of the oli mers to infinite chain lengths. The results show that the hole/electron injection/transport abilities and the optical properties of the polymers are significantly affected by the position of the benzothiadiazole group on the silafluorene group and the position of the butyl group on the thiophene group. (SiF2-DHTBT1-m)_n and (SiF1-DHTBT1-m)_n [hereafter SiF and DHTBT are silafluorene and 4,7-di(2-thienyl)-2,1,3-benzothiadiazole, respectively] show od hole and electron injection performances but (SiF1-DHTBT1-o)_n and (SiF1-DHTBT1-p)_n exhibit poor carrier injection performances. The predicted emission spectra of the polymers are located in the red visible-light range, except in the case of (SiF1-DHTBT1-o)_n.

A vacuum-assisted precipitation method was used to synthesize Fe₃(PO₄)₂·8H₂O (FP). The FP was then used to synthesize carbon-coated LiFePO₄ (LFP/C) particles. The influence of FP on the structure, morphology, and electrochemical performance of LFP was investigated. The X-ray diffraction (XRD) patterns and molar ratio of Fe to P showed that the FP which was produced using a vacuum-assisted method was of high purity and gave highly crystalline, impurity-free LFP. Scanning electron microscopy (SEM) showed that the FP contained undeveloped particles. The undeveloped FP results in uniform LFP/C particles, without agglomeration. Transmission electron microscopy (TEM) showed that the LFP particles were coated with a homogeneous carbon layer. The LFP/C showed excellent discharge capacities of 140, 113, and 100 mAh·g^-1 at 1C, 10C, and 20C rates, respectively. The cyclic voltammograms (CVs) of LFP showed a low polarization voltage and sharp redox peaks. The charge-discharge platform curves showed that LFP had an excellent high-rate capability. Electrochemical impedance spectroscopy (EIS) tests showed that the lithium-ion diffusion coefficients of LFP/C produced with and without vacuum assistance were 1.42×10^-13 and 4.22×10^-14 cm²·s^-1, respectively, proving that vacuum assistance can improve the diffusion coefficients of LFP/C.

Single-crystal TiO₂ nanorod arrays (TNRs) are proposed to increase the electron transport rate and improve the cell performance of quantum dot- sensitized solar cells (QDSCs). However, the specific surface area of TNRs is much lower than that of TiO₂ nanoparticle films, which leads to lower quantum dot adsorption and lower power conversion efficiency (η). In our investigation, TiCl₄ solution was used to modify single-crystal rutile TNRs. The modification resulted in the synthesis of a large number of TiO₂ nanoparticles on the surfaces of nanorods, which significantly increased the surface area and quantum dot adsorption of TNRs. When the TiCl₄ modification time was 60 h, the short-circuit photocurrent density (J_sc) and η of TNRs based CdS/CdSe co-sensitized QDSCs increased from (2.93±0.07) mA·cm^-2 and 0.36%±0.02% to (8.19±0.12) mA·cm^-2 and 1.17%±0.07%, respectively. In addition, intensity modulated photocurrent spectroscopy measurements indicated that the electron transport rate in modified single-crystal rutile TNRs is faster than that in anatase TiO₂ nanoparticle films, which is a desirable result.

This article describes the electrochemical performance of a novel interconnected porous carbon/ MnO₂ (IPC/MnO₂) composite prepared by in situ self-limiting deposition under hydrothermal condition. The morphology and structure were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA), and the electrochemical behavior was investigated using cyclic voltammetry (CV), charge-discharge tests, electrochemical impedance spectroscopy (EIS), and cycle life tests. The results showed that MnO₂ grew homogeneously on the IPC surface, forming a hierarchical microstructure. The MnO₂ had a typical K-Birnessite-type crystal structure and the MnO₂ content was about 34%(w). At high synthetic temperatures, the MnO₂ particles on the IPC surface were smaller. The prepared electrode material exhibited a od electrochemical capacitance performance. As the reaction temperature increased, the specific capacitance of the IPC/MnO₂ composite first increased and then remained constant. The IPC/MnO₂ composite synthesized at 100 ℃ had the maximum specific capacitance, 411 F·g^-1, in a three-electrode system. An asymmetric supercapacitor was constructed with the IPC/MnO₂ composite as the positive electrode and activated carbon (AC) as the negative electrode, in a 1 mol·L^-1 Na₂SO₄ electrolyte. The results showed that the corresponding potential window increased from 1 to 1.8 V. The maximum specific capacitance of the asymmetric supercapacitor was 86 F·g^-1 and a od rate capability was achieved.

A tungsten carbide and tungsten-iron carbide composite with a core-shell structure was prepared through a combination of surface coating and in situ reduction-carbonization, using ammonium metatungstate as the tungsten source and iron hydroxide as the iron source. The main crystal phases of the composite were tungsten-iron carbide (Fe₃W₃C), monotungsten carbide (WC), and bitungsten carbide (W₂C). In the core-shell composite, Fe₃W₃C formed the core, and the shell consisted of WC and W₂C. The electrocatalytic activity for methanol oxidation of the composite was measured by cyclic voltammetry with a three-electrode system in acidic, neutral, and alkaline aqueous solutions. The results show that the electrocatalytic activity of the composite is higher than those of tungsten carbide particles and mesoporous hollow microspheres. The activity is affected by the properties of the solution in which the reaction is performed, and is related to the crystal phase and microstructure of the composite. These results indicate that the electrocatalytic activity of tungsten carbide can be adjusted by changing the properties of the reaction solution and controlled by adjusting the crystal phase and microstructure of the composite. Furthermore, the activity can be improved through formation of a core-shell structure; this is an efficient way to improve the electrocatalytic activity of tungsten carbide.

A hetero-layered MnO₂/NiCo₂O₄ composite was fabricated according to an electrostatic self-assembly process between negatively charged MnO₂-layered nanosheets and positively charged Co-Ni-layered double hydroxide nanosheets, followed by a heat-treatment process. The morphology, composition, and microstructure characteristics of the resulting material were characterized by powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman spectrometry, atomic absorption spectrometry (AAS), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). Furthermore, the electrochemical behaviors of the composite were evaluated by cyclic voltammetry (CV), galvanostatic chargedischarge, and electrochemical impedance spectroscopy (EIS). The test results indicated that the hetero-layered composite showed porous stacking structure, which increased the effective liquid-solid interfacial area, and provided a fast path for the insertion and extraction of electrolyte ions. A specific capacitance of 482 F·g^-1 was obtained in the potential window from-0.6 to 0.45 V at a current density of 1 A·g^-1. These values were therefore superior to those of pure MnO₂ or pure NiCo₂O₄.

The effects of surfactants, namely sodium dodecylbenzenesulfonate (SDBS) and hexadecyltrimethylammonium bromide (CTAB), on the interfacial shear rheological properties of partially hydrolyzed polyacrylamide (PHPAM) and hydrophobically modified polyacrylamide (HMPAM) solutions, which are used in oilfields, were studied using a biconical method. The experimental results show that the interfacial shear complex modulus of HMPAM is significantly higher than that of PHPAM, because an interfacial net structure can be formed by HMPAM molecules through hydrophobic interactions. The SDBS and CTAB molecules can form interfacial aggregates with hydrophobic blocks of HMPAM and destroy the interfacial net structure, which results in a significant decrease in the shear modulus with increasing surfactant concentration. At the same time, the properties of the interfacial film change from viscous to elastic. At low SDBS concentrations, the mixed adsorption film formed by PHPAM and a few SDBS molecules has enhanced strength. However, SDBS molecules can displace PHPAM molecules at the interface and weaken the film at higher surfactant concentrations. The cationic surfactant CTAB neutralizes the negative charge on PHPAM, leading to partial curling of the polymer chain, which decreases the film strength. Relaxation measurements confirmed our mechanism involving destruction of the interfacial net structure of HMPAM by the surfactant.

The surface properties and micellar behaviors of mixed systems composed of dodecylammonium chloride (DAC) and sodium alcohol ether sulphate (AES) have been studied in great detail. The results of this study revealed that the mixed systems possessed excellent surface activities over a wide range of molar ratios and temperature intervals. Variations in the critical micelle concentrations (cmc) and corresponding surface tension (γcmc) of the mixtures were determined over a range of molar ratios and temperatures, and several environmental factors were also evaluated, such as pH and ionic strength.

A series of Cu/ZrO₂/CNTs-NH₂ catalysts with various chromium dopings were prepared using a coprecipitation method for the synthesis of methanol by the hydrogenation of CO₂. The impact of the addition of chromium on the catalytic performance of the Cu/ZrO₂/CNTs-NH₂ catalyst was investigated in a fixed-bed plug flow reactor. When the chromium loading was set to 1% of the total amount of Cu²⁺ and Zr⁴⁺, the methanol yield increased to a maximum of 7.78% (reaction conditions: 3.0 MPa, 260 ℃, V(H₂):V(CO₂):V(N₂)=69:23:8 and gaseous hourly space velocity (GHSV)=3600 mL·h^-1·g^-1). The catalysts were characterized by N₂ physisorption, X-ray diffraction (XRD), temperature-programmed desorption of H₂ (H₂-TPD), X-ray photoelectron spectroscopy (XPS), temperature- programmed desorption of CO₂ (CO₂-TPD), differential thermal analysis (DTA), and scanning electron microscopy (SEM). The results of these analyses indicated that the introduction of chromium reduced the size of the Cu nanoparticles, enhanced the dispersion of the Cu species, inhibited the phase transformation and sintering of ZrO₂, increased the specific surface area, enhanced the amount of CO₂ adsorbed, and promoted the conversion of weakly adsorbed CO₂ species to strongly adsorbed CO₂ species. Taken together, these factors lead to a high methanol yield. However, when the chromium loading was greater than 1%, the amount Cu and Zr on the surface, as well as the size of the Cu nanoparticle reduced considerably, which led to a significant reduction in the adsorption of CO₂ species. This effect also facilitated the formation of strongly adsorbed CO₂ species, leading to lower methanol yields.

A series of metal-organic framework (MOF) materials were synthesized together with the corresponding amorphous Ru-B/MOF catalysts, which were prepared by the impregnation-chemical reduction method. These materials were subsequently evaluated for the first time as catalysts for the partial hydrogenation of benzene to cyclohexene. The results for the initial hydrogenation rate (r₀) for the different catalysts followed the trend Ru-B/MIL-53(Al)>Ru-B/MIL-53(Al)-NH₂>Ru-B/UIO-66(Zr)>Ru-B/UIO-66(Zr)-NH₂>Ru-B/MIL-53(Cr)> Ru-B/MIL-101(Cr)>>Ru-B/MIL-100(Fe), whereas the initial selectivity for cyclohexene (S₀) was of the order of Ru-B/MIL-53(Al)≈Ru-B/MIL-53(Cr)>Ru-B/UIO-66(Zr)-NH₂>Ru-B/MIL-101(Cr)>Ru-B/MIL-53(Al)-NH₂>Ru-B/UIO-66(Zr)≈Ru-B/MIL-100(Fe). The Ru-B/MIL-53(Al) catalyst exhibited the highest r₀ and S₀ values of 23 mmol·min^-1·^-1 and 72%, respectively. The characterization results demonstrated that the Ru-B amorphous alloy nanoparticles were highly dispersed on MIL-53(Al) with the average diameter of 3.2 nm. In contrast, the Ru-B nanoparticles on MIL-100(Fe) had an average diameter of 46.6 nm. The smaller Ru-B nanoparticles not only provided more active sites for the hydrogenation to occur, but could also be beneficial in the formation of cyclohexene. The reaction conditions were further optimized for the Ru-B/MIL-53(Al) catalyst. At 180 ℃ under a H₂ pressure of 5 MPa, a cyclohexene yield of 24% was obtained, highlighting the potential of MOF materials as catalyst supports for the partial hydrogenation of benzene.

Passivated, reduced passivated, and fresh Mo₂C/γ-Al₂O₃ catalysts were prepared by temperatureprogrammed reactions with a CH₄/H₂ gas mixture. The results of in situ infrared (IR) analysis revealed that the fresh Mo₂C/γ-Al₂O₃ catalyst displayed the highest level of activity at room temperature, with cyclohexane being detected as the only product. The activity of molybdenum carbide in this reaction was comparable to that of the noble metals. The results from the in situ IR spectra for CO adsorbed onto the fresh Mo₂C/γ-Al₂O₃ catalyst before and after the hydrogenation of benzene showed that Mo₂C was active for the hydrotreating processes and Mo^δ+ (0<δ<2) was the active center for the hydrogenation of benzene. The activities of the three different catalysts for the hydrogenation of benzene were studied, and the results revealed that fresh Mo₂C/γ-Al₂O₃ was the most active catalyst.

A highly active assembled Pt/TiO₂ catalyst (Pt/TiO₂-AS) was synthesized using a simple directadsorption method, in which uniformly dispersed Pt nanoparticles were directly loaded on a TiO₂ support. Compared with Pt/TiO₂ produced by wet impregnation (Pt/TiO₂-WI), the Pt/TiO₂-AS catalyst exhibited higher activity in the total oxidation of toluene, with a toluene conversion to CO₂ and H₂O of 100% at 150 ℃. The high activity remained even at high toluene concentrations and gas hourly space velocities. The properties of the synthesized catalysts were characterized using X- ray diffraction (XRD), N₂ adsorption- desorption (Brunauer-Emmett-Teller (BET) method), transmission electron microscopy (TEM), X- ray photoelectron spectroscopy (XPS), temperature-programmed reduction of H₂ (H₂-TPR), and Fourier-transform infrared (FTIR) spectroscopy. The results showed that the Pt/TiO₂-AS crystallites were smaller than those of Pt/TiO₂-WI, with fine dispersion, greater Pt⁰ exposure on the support surface, and more active Ti―O bands, giving more oxygen vacancies and reactive oxygen species. The valence states of the active centers changed significantly (Pt⁰→Pt^δ+) during stability tests; this is the main reason for the deactivation of the Pt/TiO₂-AS catalyst.

Pd-MnO_x/γ-Al₂O₃ catalysts were prepared by impregnating Pd and MnO_x on γ-Al₂O₃ supports, using an incipient wetness impregnation method, and then coating on a cordierite substrate to obtain monolithic catalysts. The catalysts were characterized using X-ray diffraction (XRD), temperatureprogrammed reduction of H₂ (H₂-TPR), low-temperature N₂ adsorption-desorption measurements, and Xray photoelectron spectroscopy (XPS). The effects of the Pd and MnO_x impregnation order on the catalytic activity, redox performance, textural properties, and surface electronic characteristics of the catalysts were studied. The experimental results showed that the activity of the catalyst co-impregnated with Pd and MnO_x on γ- Al₂O₃ was better than that of the catalyst impregnated sequentially with Pd and MnO_x. A synergetic effect was observed between Pd and MnO_x on the Pd-MnO_x/γ-Al₂O₃ catalysts for ozone decomposition. The effects of various supports on catalytic activity, redox performance, textural properties, and surface electron characteristics of the catalysts were also investigated. The results indicated that the catalytic activities of Pd-MnO_x/La-Al₂O₃ and Pd-MnO_x/SiO₂ catalysts were the best; ozone conversion reached 82% at 14 ℃ and ozone was completely decomposed at 36 ℃. The activity of the Pd-MnO_x/γ-Al₂O₃ catalyst was second better, but the activity of the Pd-MnO_x/Zr-Al₂O₃ catalyst was poor. The support clearly affects the reducibility of PdO and MnO_x. The redox performances of MnO_x impregnated on different supports followed the order: Pd-MnO_x/SiO₂>Pd-MnO_x/La-Al₂O₃>Pd-MnO_x/γ-Al₂O₃>Pd-MnO_x/Zr-Al₂O₃.

Photoactive TiO₂ nanostructured films (i.e., nanoflowers and nanowires) have been directly synthesized on Ti sheets using an alkali-hydrothermal route. Ultrafine noble metals (i.e., Au, Pt, Pd) nanoparticles (NPs) were homogenously dispersed onto the TiO₂ nanostructures using a facile low temperature electrostatic self-assembly approach. The resulting noble-metal/TiO₂-nanostructured films supported on Ti sheets had an all-in-one structure with all of the virtues of a porous framework and enhanced photocatalytic activity. Ultra highresolution field-emission scanning electron microscopy (FESEM) revealed that the noble metal NPs were uniformly dispersed on the TiO₂ surface with od physical separation properties. The average sizes of the loaded Au, Pt, and Pd NPs were approximately 4.0, 2.0, and 10.0 nm, respectively. Noble metal NPs were deposited not only on the film surface but also in the interior framework of the TiO₂ films with a depth of more than 580 nm, as revealed by Auger electron spectroscopic (AES) in-depth profiling analysis. X-ray photoelectron spectroscopy (XPS) analysis revealed that the Pt and Pd NPs had been partially oxidized to PtO_abs and immobicompletely oxidized to PdO, respectively, whereas the Au NPs remained in a metallic state after being annealed in air at 300 ℃. During the electrostatic self-assembly process, the loading of the noble metal can be adjusted by controlling the assembly time and the colloidal pH value. The degradation of aqueous methyl orange showed that the Au/TiO₂ (or Pt/TiO₂)-nanostructured films possessed remarkably enhanced photocatalytic activity compared with pure TiO₂ films, and revealed that the metal NPs played a positive role in separating photogenerated hole-electron pairs. However, the deposited PdO species had no discernible impact on the activity of the TiO₂ nanostructures.

A series of Mo-modified Pt/C catalysts were synthesized, using a microwave-assisted technique, and the effects of pH value on the electrocatalytic performance of the resulted catalysts for ethanol oxidation were investigated. X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) were employed to characterize the crystal structures, morphologies, particle sizes and the distributions, and electronic states of the catalysts. Cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) were used to investigate the catalytic performances. The results revealed that alkaline environments are beneficial in the syntheses of catalysts with small and uniformly dispersed particles on the carbon support. The catalyst prepared at pH 14 exhibited the smallest catalyst particles, highest electrochemical surface area, best electrocatalytic activity, and durability for ethanol oxidation.

A series of malononitrile derivatives (D1-D7) with different electron donors and conjugation lengths were designed and synthesized. Their structures were characterized using ¹H and ¹³C nuclear magnetic resonance (NMR) spectroscopies, and high-resolution mass spectrometry (HRMS). Their linear photophysical properties were investigated in dimethylformamide (DMF) solutions, their optical stabilities were investigated using photobleaching experiments, and their thermal stabilities were determined using thermogravimetric analysis (TGA). The optical limiting behaviors of D1-D7 under an 800 nm femtosecond pulsed laser (Ti:sapphire laser, ~130 fs, 1000 Hz) were investigated. The results showed that four of the compounds (D4-D7), which had dialkylamines as electron donors, exhibited significant optical limiting behaviors, based on two-photon absorption (2PA), but the other three compounds (D1-D3), which had either weak donors or short conjugation lengths, showed very weak optical limiting behaviors. All the compounds had od photochemical and thermal stabilities. The 2PA cross-sections and optothermal stabilities of this series of compounds increased with increasing conjugation length or electron-donating ability of the alkylamine groups in their structures. D7, which had the best properties, is a potential candidate for optical limiting applications under an 800 nm femtosecond pulsed laser.

The photoisomerization kinetics of IR125 and HDITCP in ionic liquids with different cation alkyl chain lengths were investigated by measuring their fluorescence lifetimes and quantum yields using steady-state absorption and fluorescence spectroscopies, and time-correlated single-photon counting experiments. It was found that the photoisomerization rate constants for IR125 and HDITCP in all the selected ionic liquids were almost identical and did not change with increasing ionic liquid viscosity. A comparison of the photoisomerization rate constants of IR125 and HDITCP in isoviscous aqueous glycerol solutions with those in ionic liquids showed that the photoisomerization energy barriers of IR125 and HDITCP in ionic liquids were about 2 kJ·mol^-1 higher than those in the isoviscous aqueous glycerol solutions, indicating that specific interactions between IR125 or HDITCP and the ionic liquid restrain their respective photoisomerization processes in highly viscous ionic liquids.

Quantum dots (QDs) have recently attracted considerable attention due to their unique optical properties and potential applications in biomedicine and optoelectronics. Although the organic synthesis of QDs is popular, aqueous synthesis is also very attractive not only for its low cost, low toxicity, and low reaction temperature, but also because the as-prepared QDs can be used directly for bio-related applications without the requirement for complicated surface modification processes. However, the monodentate ligands typically used for aqueous synthesis have limited binding ability, which can lead to weak colloidal stability and low photoluminescence. To solve these problems, we explored the use of multidentate thiol-containing polymer (PAASH) as a ligand to synthesize CdTe QDs and studied the influence of the ligand on the growth mechanism and photoluminescent properties of the QDs. PAA-SH was synthesized by conjugating cysteamine to poly(acrylic acid) (PAA) in the presence of dicyclohexylcarbodiimide. CdTe QDs of different sizes were prepared in aqueous solutions using PAA-SH as a ligand under microwave irradiation. The resulting PAA-SH-capped CdTe QDs show high photoluminescence quantum yield (PLQY) (up to 75%) without CdS shell coating, which is much better than the CdTe QDs synthesized using monodentate ligands. Furthermore, the hydrodynamic diameter of the PAA-SH-coated CdTe QDs is about 10 nm, and therefore much smaller than the polymer or SiO₂ encapsulated QDs. In contrast, benefitting from cooperative binding effect of the multiple thiol groups and the high free energy for the ligand detachment from the QDs surface, PAA-SH-CdTe QDs show high storage stability.