We review recent research on fluorophosphate and orthosilicate cathode materials for lithium ion batteries. Emphasis is placed on the relationship between structures, methods of preparation and properties of the cathode materials. We especially focus on factors leading to an improvement in their electrochemical performance. Trends of research into fluorophosphate and orthosilicate cathode materials are also discussed.

The synergistic inhibitive effect of sodium dodecylbenzene sulfonate (SDBS) and hexamethylene tetramine (HA) toward Q235 steel in hydrochloric acid was investigated by the static weight loss method. We also studied the inhibition mechanism by molecular dynamics simulations with regard to the inhibition of aggressive particle diffusion by inhibitor membranes. SDBS and HA were found to have individual inhibition efficiencies of 82.82% and 79.46%, respectively. These inhibition efficiencies increased to an efficiency of 92.78% when SDBS and HA were combined. Molecular dynamics simulations indicated that the free volume of the inhibitor membrane decreased significantly when SDBS and HA were used together compared with the case when they were used individually. Therefore, the self-diffusion of the inhibitor molecules becomes weaker and passive diffusion of the aggressive particles, which is caused by the mobility of the membrane, also decreases. The diffusion coefficient of the aggressive particles inside the inhibitor membrane shows that the diffusion of the aggressive particles is strongly hindered by the inhibitor membrane because of the synergistic effect between SDBS and HA and that the inhibition efficiency is enhanced.

The super thermite Al/CuO precursor was prepared using Cu(NO₃)₂·3H₂O, C₂H₅OH, 1,2-epoxy propane and nano-Al as raw materials under ultrasonic conditions by the sol-gel method. Our results show that the precursor components are Al and Cu₂(OH)₃NO₃. The thermal behavior and thermal decomposition mechanism of the nano super thermite Al/CuO precursor were investigated by thermogravimetric- differential scanning colorimetric-Fourier transform infrared spectrum-mass spectrometry analysis (TG- DSC-FTIR-MS). The decomposition reaction kinetics of the precursor was investigated by TG-DTG analysis at different heating rates and the kinetic parameters were calculated using six kinetic analytical methods. The activation energy, reaction order, frequency factor and other kinetic parameters were obtained and the kinetic equation of the decomposition process could be expressed as: dα/dt=10^14.0×4α^3/4exp(-2.0×10⁴/T).

The structural and thermodynamic properties of aqueous dimethyl sulfoxide (DMSO) at a mole fraction of 0.002 were investigated using referenced interaction site model theory at different temperatures. The results reveal that the water network structure is enhanced by the presence of DMSO. The increased fluctuation in the potential of mean force suggests that the water-induced force is repulsive. In addition, the increased entropy of solvation and free energy of solvation imply that the randomness of the solution increases with an increase in temperature. The increased interaction energy and excess chemical potential reveal that the solution deviates from an ideal solution. Furthermore, the increased cavity reorganization energy shows that the system structure reorganizes easily at high temperature.

The phase equilibrium condition for gas hydrates has been an important and difficult subject in gas hydrate-related research. In this paper, the mechanism of the effect of pore-size distribution on the phase equilibrium is first explored and the concept of effective pore radius is proposed. Using information on the pore-size distribution of sediments, a relationship between hydrate saturation and effective pore radius is developed. Combined with the van der Waals-Platteeuw model, this relationship was then used to develop a new phase equilibrium model for gas hydrates in sediments, which can properly account for the effect of pore-size distribution. In contrast to the traditional models, this new model does not represent a curve on the p-T plane but instead addresses the relationship between the temperature, pressure, and hydrate saturation. Such a feature allows the new model to take into account the effect of pore-size distribution on the phase equilibrium while treating the formation and/or dissolution processes of gas hydrates in pores more realistically. The simulated results were compared with the experimental data available in literature showing that the new model gives better results compared with the other traditional models. Given the temperature and the pore pressure, the hydrate saturation can be determined using the proposed model. Therefore, the new model can be used to estimate the amount of hydrate resources in the field.

Density functional theory with the B3LYP level was used to investigate the nonlinear optical properties of 8-hydroxyquinolinolate (Ag, Pt)(AgQ, PtQ₂) metal complexes and their derivatives. The introduction of substituents resulted in considerable red shifts for the highest absorption wavelength of the Pt complexes. The lowest energy excitation absorption mainly consisted of d→π^* and π→π^* excitations from the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO). Metal to ligand charge-transfer (MLCT) and ligand to ligand charge-transfer (LLCT) were mainly involved. Adulteration with the transition metals Pt and Ag resulted in a significant increase in the third-order nonlinear optical coefficient γ of 8-hydroxyquinolinolate. The introduction of ―Ph, ―PhOCH₃, ―PhF₂, and ―PhF₅ further improved the γ value of the 8-hydroxyquinolinolate metal complexes. The gradient of the γ value increased with an increase in the electron-donating ability of the introduced substituent. This gradient was lower for substituent with a higher electron-accepting ability.

We investigated the structures, infrared spectra, and reactivities of (+)-catechin (Cc, C₁₅H₁₄O₆) and its metal complexes (M-Cc, M=Ca, Zn, Cd, Cu, Al, Cr) using density functional theory (DFT) with the B3LYP functional and the 6-311+G(d,p) basis set for non-metallic elements and the LANL2DZ basis set for metals. The results showed that the M-Cc complexes were structurally and spectroscopically different from their precursor (Cc). The frontier molecular orbitals and conceptual density functional theory descriptors imply that some of the M-Cc systems tend to be more active than the Cc monomer. Different metal complexes were found to have different values for the indices. These results are helpful in understanding the studied properties of (+)-catechin and other metallic compounds.

Density functional theory (DFT) with the B3LYP functional was used to investigate the electronic structures and nonlinear optical (NLO) properties of a series of pyridine-based Ru(II) complexes containing thiophene rings. The results indicate that stable chemical bonds do not form between the coordinated atoms and the metal ion for [Ru^II(NH₃)₅L]²⁺ (L: organic groups containing the thiophene ring) complexes. However, strong donor-acceptor (D-A) interactions do exist. The Ru(II) and carbon atoms form stable σ-π coordinated bonds after NH3 is substituted by CO, which decreases the unoccupied orbital energies of the acceptor groups. The degree of system conjugation increases because of an increase in the number of thiophene rings, which is favorable for intramolecule charge transfer. The polarizability α and the first-order hyperpolarizability β values of all the systems are enhanced significantly because of the abovementioned reasons. According to the frontier molecular orbitals, the contribution to the second-order NLO coefficient mainly comes from an intraligand charge transfer (ILCT) and an interligand charge transfer (LLCT). The introduction of CO increases the β value for the [Ru^II(CO)₅L]²⁺ complex about seven times compared with the [Ru^II(NH₃)₅L]²⁺ analogue, which can be attributed to a ligand-to-metal charge transfer (LMCT).

In this paper, styrene epoxidation with hydrogen peroxide was used as a model reaction. The Dmol³ implementation in the Materials Studio Software was used to simulate the mechanism of the model reaction. Solvent effects in the reaction were also studied using the conductor-like screening model (COSMO) as a part of the continuum model in three solvents: water, ethanol, and tert-butyl alcohol. To investigate the micro-process wherein the solvent molecules react with the solute molecules directly, the discrete model was employed to simulate the impact of a single molecule of water, ethanol and tert-butyl alcohol on the reaction. Consistent results were obtained for the two different solvent models. Reaction activity was most favorable for the tert-butyl alcohol followed by ethanol. Protic solvent molecules promote the heterolytic cleavage of hydrogen peroxide and form active oxygen species, which can reduce the reaction barrier.

The detailed mechanisms of CO oxidation catalyzed by AuAg^-, AuCu^-, and AgCu^- were investigated using density functional theory at the B3LYP level. The computational results indicate that the adsorption site of CO onto the mixed clusters decreases as follows: Cu>Au>Ag. Copper is the preferred adsorption site for O₂ on the binary clusters. The adsorption of O₂ onto ld was found to be the weakest. Three reaction pathways exist for CO oxidation catalyzed by AuAg^-, AuCu^-, and AgCu^-. The most feasible pathway for CO oxidation catalyzed by AuAg^- is CO insertion into the Ag―O bond of AuA ₂^- to produce the [Au―AgC(O―O)O]^- intermediate, which then decomposes into CO₂ and AuA ^-, or another CO molecule attacks [Au―AgC(O―O)O]^- to form two CO₂ molecules and AuAg^- anion. A feasible pathway for CO oxidation catalyzed by AuCu^- or AgCu^- is initiated by the co-absorption of CO and O₂ onto the clusters followed by the formation of a four-membered ring intermediate to produce the corresponding products. The cooperation effect of the second CO is very weak. The catalytic activities of AuAg^- and AuCu^- toward CO oxidation are stronger than that of Au₂^- . Doping the Au clusters with Ag and Cu increases the catalytic activity. These results are in agreement with the previous experimental results.

A direct density functional theory dynamics method was used to determine the mechanism and kinetics of the CH₃OCF₂CF₂OCH₃+Cl reaction. Potential energy surface information was obtained at the BB1K/6-31+G(d,p) level. The hydrogen abstraction channels and displacement processes of the two stable conformers (SC1 and SC2) of CH₃OCF₂CF₂OCH₃ were taken into consideration. Theoretical rate constants of the individual H-abstraction channels (one from SC1 and two from SC2) were calculated by improved canonical variational transition state theory (ICVT) with a small-curvature tunneling (SCT) correction. The overall rate constant (k_T) was obtained by considering the weight factor of each conformer from the Boltzmann distribution function and the contribution of the two conformers to the whole reaction was discussed. The calculated k_T(ICVT/SCT) at 296 K agrees well with the experimental value. Since experimental data were lacking for other temperatures, a three-parameter rate constant temperature expression for the total reaction within 200-2000 K was fitted to: k_T=0.40×10^-14T^1.05exp(-206.16/T).

We constructed a nested prediction model based on support vector machines (SVM) and the KStar method. The models consisted of a molecular shape discriminative model for metabolites, which was used to predict the o-dealkalytion reaction mediated by cytochrome P450, in addition to the metabolic site discriminative model, which was used to judge C―O bond breaking in molecules. We calculated 1280 molecular descriptors including topological descriptors, 2D autocorrelation descriptors, and geometric descriptors to characterize the physicochemical properties of 272 molecules. A molecular shape discriminative model, represented by the classification models, was constructed by machine learning methods including SVM, decision tree, Bayesian network, and k nearest neighbors method. The results showed that the SVM model was superior to the other methods. Twenty-six quantum chemical features including charge-related, valency-related, and energy-related features were calculated for the 538 metabolism sites for the o-dealkylation reaction in the metabolic site discriminative model. Machine learning methods including decision tree, Bayesian network, KStar, and the artificial neural network method were also used to develop classification models. It showed that the KStar model with its prediction accuracy, sensitivity, and specificity of more than 90% outperformed the other classification models. Fifteen traditional Chinese medicine medicinal molecules were used to validate the model. The results showed that the nested models had a certain accuracy and could contribute to the prediction of metabolites from traditional Chinese medicines.

We calculated the geometrical and electronic structures, rotational and vibrational frequencies, and energetics of different complexes formed by 15 conformers of proline (Pro) with atomic and cationic Ag using the hybrid density functional method X3LYP and the LACV3P^**++ basis set together with effective core potentials. The Pro-Ag system gave 17 stable complexes and the Pro-Ag⁺ system gave 23 stable complexes. The results show that: (1) only 9 conformers of proline are present in the Pro-Ag complexes but all are present in the Pro-Ag⁺ complexes. The most stable complexes are not formed by the lowest energy conformer of proline with Ag and Ag⁺. (2) The main interaction between atomic Ag and proline is a van der Waals interaction because of its 4d¹⁰5s¹ electronic configuration. However, Ag⁺ binds strongly to proline with some σ-coordination bonding character due to the empty outermost 5s5p valence shell. Both particles can be mono- or bi-coordinate in complexes with proline. A non-conventional O―H…Ag hydrogen bond exists. (3) The binding energy between Ag and proline is less than -19 kJ·mol^-1 but the binding energy of the Pro-Ag⁺ complex changed from -117 to -255 kJ·mol-1. The latter system was found to be more stable. (4) Ag carries a small amount of negative charge in two types of complexes according to natural bond orbital (NBO) population analysis and the energy differentce of front orbital values (Δε) of the complexes are lower than that of the Ag and proline fragments. The O―H and N―H bond stretching frequencies were found to be red shifted or blue shifted in some complexes.

The simulations of O₂ and CN adsorption on copper activated sphalerite (110) surface are performed by using plane wave-pseudopotential approach based on density functional theory. The results show that the density of states of 3d orbital of Cu atom on the activated sphalerite surface is located around the Fermi level, which can enhance the reactivity of the sphalerite surface. O₂ adsorption is unavailable on unactivated sphalerite surface, while the Cu and S atoms on the copper activated sphalerite surface can donate electrons to the anti-bonding orbital π_2p^* of the O atom to form the adsorption bonding. The simulation of CN adsorption shows that copper activation improves the adsorption between CN molecule and the sphalerite surface. The Cu d orbital interacts with C p orbital to form a back donating π bonding, and the S atom interacts with the N atom.

First-principles calculations based on density functional theory were carried out to study the effects of monovacancy and boron doping on Si adsorption on graphene. We found that Si single atom, sitting above the bridge site of defect-free graphene, was the most stable configuration. The spin properties of the C atoms change after Si adsorption. In our calculations, monovacancy and substituting with B atoms enhanced Si adsorption on graphene and monovacancy was more effective than the B dopant. No magnetic moment was observed for the Si adsorbed on these two systems. B doping induces a stable Si adsorption position from the bridge site to the top site and increases the conductivity of the graphene system. By comparison, B doping in the graphene system is relatively stable while the monovacancy system is not.

The adsorption and diffusion of polyethylene (PE) with different degrees of polymerization (N) on a silicon (111) surface were studied by molecular dynamics simulations. The relative dielectric constant was selected to be 1 and 78 to mimic a vacuum and a solution environment, respectively. The chains were all present as two-dimensional (2D) adsorption conformation on the surface but different conformations and dynamic properties were found in the two absolutely different environments. This shows that the solvent plays an obvious role in the chain adsorption and diffusion processes on a hydrophobic surface. The relationship between the adsorption energy and the degree of polymerization follows a linear function and the average adsorption energy per segment is -0.38 kJ·mol^-1. In addition, the diffusion coefficient (D) of these chains scales with the degree of polymerization as N^-3/2.

Hydrated clusters of Sr²⁺/Ba²⁺(H₂O)_n (n=1-6) were investigated by the ab initio method and the ABEEM/MM fluctuating charge molecular force field. ABEEM/MM potential functions of cation-water interactions were constructed based on the stable structures and binding energies of the hydrated clusters were obtained. The results from ABEEM/MM are consistent with those from the ab initio method. Furthermore, Sr²⁺ and Ba²⁺ aqueous solutions were studied by ABEEM/MM molecular dynamic simulations. Results show that for the Sr²⁺ aqueous solution the first and second peaks of the SrO radial distribution function (RDF) are located at 0.257 and 0.464 nm, respectively. The coordination numbers of the water molecules for the first and second hydration shells are 9.2 and 11.4, respectively. For the Ba²⁺ aqueous solution, the first and second peaks of the BaO RDF are located at 0.269 and 0.467 nm, respectively. The coordination numbers of water molecules for the first and second hydration shells are 9.9 and 12.4, respectively. These results also show od consistency with experimental observations and other theoretical simulations. Compared with the external water molecules, the water molecules in the first hydration shell are evidently polarized by the cation and their O―H bond lengths are stretched while the HOH bond angles are found to be reduced.

We investigated the magnetism, electronic and band structures of hexa nal HoMnO₃ using density functional theory (DFT) within the generalized gradient approximation (GGA) and combined this with the projector augmented wave (PAW) method. The relative experimental results are explained using non-collinear magnetic structure calculations. The calculations show that the total energy of the unit cell decreases and the energy gap as well as magnetic moment of Mn³⁺ increases. Each atom coordinate was close to the experimentally measured values and the electronic densities of states of the HoMnO₃ qualitatively agreed with the results from X-ray absorption spectroscopy, when the noncollinear triangular antiferromagnetic configurations of the Mn³⁺ ions in the ab plane were taken into account. According to the densities of states and band structure analysis, as calculated within the noncollinear magnetic structure, we found that the two experimentally determined optical absorption peaks near 1.7 and 2.3 eV were due to interband transitions between the oxygen states that hybridize strongly with different Mn orbitals and the Mn [3d_3z²-r²] state. The strong orbital hybridization between Ho 5d and O(3, 4) 2p in the plane drives the ferroelectric polarization of the HoMnO₃ to the ab plane.

High temperature steam electrolysis (HTSE)，which is the electrolysis of steam at high temperature with high efficiency using planar solid oxide electrolysis cell (SOEC) technology, has received an increasing amount of international interest because of its potential for large-scale hydrogen production using nuclear hydrogen in future. However, it is of great importance to control polarization energy loss and performance degradation for a practical HTSE process. In this paper, the distributions of the polarization resistances of the LSM/YSZ/Ni-YSZ (LSM: Sr doped LaMnO₃; YSZ: Y₂O₃ stabilized ZrO₂) cell under a real operating state and using different operating modes were investigated by electrochemical impedance spectroscopy (EIS). We discussed the differences between the SOEC and the solid oxide fuel cell (SOFC) while the steam diffusion process in the cathode support layer of SOEC was determined to be the rate-determining step. Based on the above-mentioned research, the microstructure of the cathode support layer was adjusted and optimized by polymethyl methacrylate (PMMA) pore formers. The results show that the SOEC cell gives much better performance after the optimization. The porosity increased by 50% when PMMA was used. The hydrogen production rate was as high as 328.1 mL·cm^-2?h^-1 (nominal) when using an electrolysis voltage of 1.3 V, which was about 2 times as that of the starch pore formers. The cell was operated stably for more than 50 h. Our research provides theoretical data and establishes a technical foundation for further study into and application of this novel technology.

The LaMg_8.40Ni_2.34 alloy was prepared by vacuum induction melting and subsequent heating treatment. The phase structure, morphology, and hydrogen storage properties were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and pressure-composition-temperature (PCT) measurements. The LaMg_8.40Ni_2.34 alloy was composed of La₂Mg₁₇, LaMg₂Ni, and Mg₂Ni phases. The alloy can be activated in the first hydriding/dehydriding process. Its reversible hydrogen storage capacity was 3.01% (mass fraction) at 558 K. PCT curves showed two hydriding plateaus corresponding to the formation of MgH₂ and Mg₂NiH₄ and only one dehydriding plateau, which is due to the synergetic effect of hydrogen desorption between MgH₂ and Mg₂NiH₄. The activation energy values of LaMg_8.40Ni_2.34 alloy were (52.4±0.4) and (59.2±0.1) kJ·mol^-1 for the hydriding and dehydriding processes, respectively, and these were lower than that of the Mg₂Ni alloy. The LaMg_8.40Ni_2.34 alloy exhibited od activation behavior, hydrogen adsorption and desorption reversibility, and kinetic properties.

We prepared rutile TiO₂ powders of od crystallinity by hydrolyzing a Ti(OC4H9)4 precursor at room temperature and by reprecipitation. X-ray diffraction (XRD) revealed that higher acidity, lower temperature, and specific amounts of Cl^- as a medium result in rutile TiO₂. This rutile TiO₂ has an irregular rice-like structure. After adding the P105 (EO₃₇PO₅₆EO₃₇) tri-block copolymer as a structural agent, the rutile TiO₂ aggregated to form rough 350 nm spheres. These rough spheres have a greatly enhanced light harvesting efficiency and improved energy conversion efficiency in dye-sensitized solar cells. This is due to their high light scattering effect and larger surface area (109.5 m²·g^-1). By adding these large rutile spheres at a mass fraction of 25% to the over-layer of a TiO₂ film composed of ~20 nm TiO₂ particles as light scattering centers, the energy conversion efficiency of the dye-sensitized solar cells (DSSC) was 7.27%. This is a 17% increase in conversation efficiency compared with the DSSC based on a TiO₂ photoanode without these rough rutile spheres.

N3 dye and Al₂O₃ were used to form an alternating assembly structure. The current density-voltage (J-V) characterization showed that this structure improved the performance of dye- sensitized solar cells (DSCs). Electrochemical impedance spectroscopy (EIS) was used to study the internal resistance of this alternating assembly structured DSCs. The results showed that the resistance at the sensitized TiO₂/electrolyte interface decreased as the number of (dye/Al₂O₃) units increased, and the device's conversion efficiency improved significantly. Based on the EIS results, a series of equivalent circuit models were well established to investigate the dye/Al₂O₃ alternating assembly structure theoretically.

A dye-sensitized solar cell (DSSC) based on a 3-aminopropyltrimethoxysilane (APTS)- modified TiO₂ electrode was fabricated. This cell generated a short current of 18.32 mA·cm^-2, an open voltage of 775.9 mV, and its overall photo-to-electricity conversion efficiency was 9.15% under 100 mW·cm^-2 white light irradiation from a xenon lamp. The three DSSC parameters for the bare TiO₂ electrode were found to be 18.08 mA·cm^-2, 749.9 mV, and 7.70%. Compared with the unmodified solar cell, the overall conversion efficiency improved by 18.8% and the fill factor improved from 0.57 to 0.64. This improvement is attributed to the inhibition of the back reaction at the interface between the semiconductor and the electrolyte. The dark current-applied voltage curve shows that the onset voltage shifts from -0.30 to -0.40 V, which indicates a reduction in defects and surface states on the TiO2 surface because of the presence of APTS. Furthermore, special experiments were conducted to investigate the interaction among TiO₂, APTS, and the cis-Ru(dcpyH₂)₂(SCN)₂ dye. In these experiments, APTS and the dye were self- assembled onto a TiO₂ electrode in layers. The interaction was characterized by X-ray photoelectron spectroscopy (XPS). Qualitative and quantitative results showed that the ―OCH₂CH₃ was partially removed and it formed mono-bridge or bi-bridge Si―O―Ti bonds. The cis-Ru(dcpyH₂)₂(SCN)₂ dye adsorbed onto APTS through an electrostatic interaction between ―COOH and ―NH₂ from the dye. FT-IR spectra further confirmed this inner interaction.

Blocking layer thin films were prepared on a conductive fluorine-doped tin oxide (FTO) substrate by the hydrolysis of TiCl₄ solution with different concentrations. This blocked the recombination between photoelectrons and I₃^-. Blocking layer compositions were characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The surface morphology and transmittance were determined by field emission scanning electron microscopy (FE-SEM) and UV-visible spectrophotometry. The photovoltaic performance of the dye-sensitized solar cells (DSSC) was measured under AM1.5 illumination and under dark conditions. We found that the blocking layers were composed of TiO₂ particles. Increasing the concentration of TiCl₄ in solution leads to an increase in the blocking layer thickness. Apart from the increase in thickness, the morphology develops as the concentration increases. The transmittance of FTO decreases after the blocking layers deposit on the surface and the blocking layers prepared using 0.04 mol·L^-1 TiCl₄ solution can suppress the dark current most efficiently and we thus obtained the highest power conversion efficiency of 7.84% under AM1.5 illumination conditions.

We applied the “selenization of stack element layers” method to the preparation of CuIn_1-xGa_xSe₂ (CIGS) films. The selenium vapor concentration was precisely controlled to optimize the annealing process using a homemade bilayer tubular selenization facility, and its effect on the photoelectric characteristics of the films was studied. Auger electron spectroscopy (AES) and X-ray diffraction (XRD) were used to analyze the composition distribution in the cross-section and to obtain phase information, respectively. The output performance of the CIGS device was also measured under AM1.5 1000 W·m^-2 illumination. The results indicated that the molybdenum back contact layer was seriously degraded by the saturated selenium vapor during annealing. Annealing with a low concentration of selenium vapor led to bad performance because of segregation and defects in the film. The CIGS film was homogeneous after annealing in a selenium-free inert atmosphere and a conversion efficiency of 8.5% was obtained.

Layered LiNi_0.5Mn_0.5O₂ was synthesized by a solid state reaction method under air or oxygen atmosphere. The obtained materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), electrochemical impedance spectroscopy (EIS), and charge-discharge tests. The results show that the LiNi_0.5Mn_0.5O₂ synthesized by the solid state reaction method under both air and oxygen atmospheres give a pure phase and od crystallinity, however, their electrochemical performance differs. The material synthesized under oxygen gives better electrochemical performance including a higher first discharge capacity and better cycle stability. At a rate of 0.1C the first discharge capacity of the material synthesized under oxygen was found to be 178 mAh·g^-1. After 50 charge and discharge cycles the discharge capacity was still 165 mAh·g^-1 giving a capacity retention rate of 92.7%. For the material synthesized under air, the first discharge capacity at a rate of 0.1C was found to be 164 mAh·g^-1. After 50 charge and discharge cycles, the discharge capacity was 137 mAh·g^-1 giving a capacity retention rate of 83.5%. The reason for the material synthesized under oxygen having better electrochemical performance than the material synthesized under air is due to the oxygen atmosphere suppressing the Li/Ni exchange ratio in LiNi_0.5Mn_0.5O₂.

We treated carbon nanotubes (CNTs) with hydrazine hydrate and diethylenetriamine separately and characterized them using scanning electron spectroscopy (SEM) and X-ray photoelectron spectroscopy (XPS). SEM indicated that the treated CNTs retained the length/diameter ratio of the pure CNTs and XPS showed that nitrogen was doped in the CNTs. XPS analysis also indicated that the carbon/nitrogen atomic ratio of the CNTs treated by hydrazine hydrate was 95/2, which was much higher than the 96/0.5 for the CNTs treated by diethylenetriamine. The hydrophilicity of the CNTs was found to be much higher after N-doping and it increased with an increase in the N content. Therefore, the water dispersibility of the N-doped CNTs treated by hydrazine hydrate was better than that of the N-doped CNTs treated by diethylenetriamine. As electrode materials for electrochemical capacitors, nitrogen functional groups contribute to the pseudo-Faradic capacitance but their cyclic performance still needs to be improved. Because of the od hydrophilicity of the N-doping CNTs, which improves the wettability of the CNTs for the electrolyte, the specific capacitance of the N-doping CNT electrode is still slightly higher than that of the pure CNT electrode after cycling.

We reported on the capacitive behaviors regarding to the relationship between ion size and pore architecture, using activated carbons with an adjusted pore structure as electrode materials. The results revealed that an asymmetric capacitance response occurred in both electrodes. The gravimetric capacitances for the positive and negative electrodes were 113 and 7 F·g^-1, respectively. A significant current decay was presented in the negative region of cyclic voltammetry curve. Experimental and calculated maximum storage charges had a od agreement. This results suggested that the insufficiently developed pore architecture for cation accommodation led to a saturation effect on the active surface, consequently, a deteriorated capacitive performance in the negative electrode. Contrarily, when pore size was larger than tetrafluoroborate dimension, the saturation effect was not found. However, this was at the expense of the lower specific area capacitance in the positive electrode. The poor capacitive behavior of the negative electrode would limit the usable voltage of the cell system and consequently the deliverable energy and power. As a result, an optimal match between the pores size and the ion dimension with respect to each electrode would be considered to obtain the maximum capacitance for the capacitor unit.

Porous carbons were prepared by the carbonization of water soluble chitosan and they were then used to synthesize porous C/NiO composites. Transmission electron microscopy (TEM), X-ray diffraction (XRD), and nitrogen adsorption-desorption experinents were used to characterize the structure and morphology of the products. The results showed that the mesopore-rich composites consisted of NiO crystallites and porous carbon. The electrochemical properties of the porous C/NiO composites were studied by cyclic voltammetry (CV) and galvanostatic charge/discharge measurements. We found that compared with porous carbon, the composites showed superior electrochemical capacitive performance. When the mass ratio of nickel to carbon was 2:20, the composite had a large specific capacitance of 355 F·g^-1 at a current density of 0.1 A·g^-1 and excellent cyclability with a capacity retention of about 99% after 1500 cycles.

The electrochemical behavior of IrO₂ electrodes in a MnSO₄ plating solution and in a H₂SO₄ solution at different temperatures was investigated by polarity curve and cyclic voltammetry methods. The anodic electrode deposition was carried out at different current densities according to the polarity curve obtained in the bath and the deposition velocity was measured. The results show that the anodic electrode deposition reactions and the O₂ production reaction on the IrO₂ electrode in the bath occur simultaneously and the former reaction obviously restrains O₂ production. The process of MnO₂ electrodeposition onto IrO₂ is complicated and a Mn³⁺ intermediate product is produced, which can be oxidized to Mn⁴⁺ during the electrode deposition. Mn³⁺ is hydrolyzed at the same time as the oxidation and its hydrolysate desorbs, which causes an obvious reduction in current efficiency for the MnO₂ anodic electrodeposition. A potential range exists for the MnO₂ anodic electrode deposition and we also found a maximum value for the deposition velocity within the potential range.

We successfully prepared ZnO nanorod-modified Au (ZnO nanorod/Au) electrodes using one-step cathodic electrodeposition. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to characterize the morphology and crystal phase of the ZnO nanorods. The data showed that the ZnO nanorods were wurtzite type crystals with a hexa nal rod shape and a diameter of about 100 nm and that the ZnO nanorods were arranged well on the surface of electrodes. These ZnO nanorod-modified electrodes were able to detect direct electron transfer from cytochrome c (cyt c). Cyclic voltammograms showed that the direct electron transfer of cyt c with heme iron in different valence states was easily achieved by the ZnO nanorod/Au electrode. Data of amperometric responses demonstrated that a linear amperometric response to hydrogen peroxide was observed on the ZnO nanorod/Au electrodes after adsorbing cyt c.

The electrochemical properties of the Dawson-type heteropolyanion P₂W₁₈O₆₂^6- were studied in detail by cyclic voltammetry, alternating current (AC) voltammetry, and AC impedance. Cyclic voltammetry results revealed that P₂W₁₈O₆₂^6- possessed two pairs of reversible one-electron redox waves and two pairs of reversible two-electron redox waves in a solution containing 0.1 mol·L^-1 Na₂SO₄ and NaHSO₄ (pH 2.52). The peak potential and the peak current of the single-electron wave were independent of the solution pH while the peak potential of the two-electron wave shifted negatively, and the peak current decreased with an increase in solution pH. This indicated that the two-electron electrode process involved H⁺ and the involved H⁺ number was 2. AC impedance spectroscopy showed that the P₂W₁₈O₆₂^6- electrode process was fully controlled by diffusion and the diffusion coefficient (D_O) was 2.5×10^-6 cm²·s^-1. The cyclic voltammograms indicated that significant P₂W₁₈O₆₂^6- electrocatalysis towards O₂ reduction to H₂O₂ occurred as evidenced by the third wave pair and a catalytic efficiency of 300% were obtained. Application of P₂W₁₈O₆₂^6- in the degradation of nitrobenzene in the electro-Fenton-like system containing PW₁₁O₃₉Fe(III)(H₂O)^4- showed a remarkable improvement in terms of degradation efficiency.

The influences of electrolyte concentration and temperature on the capacitive behavior of activated carbon (AC) were investigated by cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge/discharge measurements. The performance of a symmetric capacitor was characterized in 0.1, 0.5, 1.0, and 6.0 mol·L^-1 KOH solution. We found that the high electrolyte concentration led to high capacitance, low internal resistance, and a narrow voltage window. The capacitance and internal resistance were found to be linearly dependent on the logarithm of KOH concentration. AC supercapacitor performance was investigated at 20, 40 and 80 °C, respectively. We found that elevated temperatures are favorable for an increase in capacitance and for a decrease in internal resistance. However, elevated temperatures increase the capacitance fading rate during long charge/discharge cycling tests.

The gelation of n-butanol was realized by a mixture of cationic and anionic surfactants (referred to as “catanionic surfactant”). In this study, we used sodium laurate/cetyltrimethylammonium bromide (SL/CTAB) as the catanionic surfactant. The rheological properties and microstructures of the n-butanol gel were studied using a rheometer and scanning electron microscopy (SEM). We found that the concentration and mole ratio of the catanionic surfactant affected the formation of the gel and n-butanol was only efficiently gelled in the presence of the catanionic surfactant at a suitable concentration and mole ratio. When we fixed the concentration of one component in the catanionic surfactant system, the gel viscosity increased with the concentration of the other component on the basis of gel formation. This gel was a non-Newtonian fluid and showed a shear-thinning property in rheological experiments. In addition, SEM results showed that the gel had a representative three-dimensional network structure, which was composed of zonal fibers with uniform thickness. Further investigation indicates that the hydrophobic effect between the hydrocarbon chains, the electrostatic attraction between the polar headgroups, and the hydrogen bond interaction between the surfactants and n-butanol play an important role in gel formation.

Catalysts with different loadings (mass fractions from 5% to 45%) of tungstophosphoric acid (TPA) on zirconia were prepared by suspending zirconia aerogel in an ethanol solution of TPA, removing the solvent via evaporation, drying and then calcining the powder at 750 °C. These catalysts were characterized by N₂ adsorption, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, FTIR spectroscopy of adsorbed Pyridine (Py-IR), and temperature programmed desorption of NH₃ (NH₃-TPD). The catalytic performances of these materials were examined for the polymerization of tetrahydrofuran (THF). The experimental results indicated that the strong interaction between TPA and zirconia retarded both the crystallization of zirconia and the destruction of the Keggin-unit of TPA. In these materials, the major tungsten species were found to be zirconia-anchored heteropolytungstates (with distorted intact and/or partially fragmented Keggin-units) and Zr-containing pseudo-heteropolyanions produced by the chemical bonding of Zr⁴⁺ with the WO_x fragments from TPA decomposition as well as some amount of WO₃. The catalysts showed both Brönsted and Lewis acidity, and the catalyst with 20% TPA loading had the highest total acidity and catalytic activity because of the monolayer coverage of the active species. Under the reaction conditions of 40 °C for 20 h, the most active catalyst, 20TPZ-750, gave a high polymer yield of 30.9%±2%. During recycling for 6 times, no obvious activity loss was observed.

Metals (Fe, Ti, Zr) were doped into mesoporous MCM-41 by a one-step method using cetyltriethylammonium bromide (CTAB) micelles with micellar solubilized metallocenes as templates. X- ray diffraction (XRD) and N₂ adsorption-desorption isotherms show that after metallocene doping, M- MCM-41(T) materials still preserved the ordered hexa nal structure and high BET surface area. Inductively coupled plasma atomic emission spectrometry (ICP-AES) indicated that the mass fractions of the metals in the corresponding samples are: 1.71% Fe in Fe-MCM-41(400), 0.95% Ti in Ti-MCM-41(550) and 0.81% Zr in Zr-MCM-41(550). All the M-MCM-41(T) materials showed a particular high catalysis effect for the esterification of acetic acid and n-butanol. The TOF of Fe-MCM-41(400) and Zr-MCM-41(550) were 55643 g·h^-1·g^-1 and 125320 g·h^-1·g^-1, respectively, which is much higher than that of the corresponding pure metallocenes.

A series of ZnO photocatalysts doped with different amounts of cerium were prepared by co-precipitation and then calcined at different temperatures. The prepared pure ZnO and Ce-doped ZnO samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), UV-visible (UV-Vis) spectroscopy, and photoluminescence (PL) spectroscopy. The photocatalytic activity of the samples was evaluated by the photodegradation of acid orange II under UV light (λ=365 nm) irradiation. FT-IR results showed that ZnO doped with 2% (w, mass fraction) cerium had far more OH groups over the surface of the doped sample than the pure ZnO. At the same time, PL tests indicated that the presence of 2% (w) cerium effectively suppressed the recombination of the photogenerated hole-electron pairs. On the other hand, the calcination temperatures influenced the crystallinity and crystal size of the catalysts. XRD tests indicated that the sample calcined at 500 °C had od crystallinity and a small crystal size while elevated temperature treatment (600-800 °C) would result in sintering and increase the crystal size. At the optimal calcination temperature of 500 °C and at 2% (w) cerium doping the composite photocatalyst had much higher photocatalytic activity and stability compared with pure ZnO. The high photocatalytic performance of the Ce doped ZnO could be attributed to an increase in surface OH groups, high crystallinity and a low recombination rate of electron/hole (e^-/h⁺) pairs.