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In this study, oxygen vacancies are successfully introduced into Li2MnO3 by low-temperature reduction. Electron paramagnetic resonance is used to detect oxygen vacancy and the results state clearly that oxygen vacancies indeed exist in the reduced samples, and R-LMO-40 shows the highest content. The relationships between oxygen vacancies content and the electrochemical performance of Li2MnO3 as cathodes for lithium ion batteries are also investigated. The oxygen-deficient samples show much better electrochemical performance compared to the pristine Li2MnO3, especially R-LMO-40 with an optimized content of oxygen vacancies. At the rates of 0.5 C, 1 C, 2 C and 5 C, R-LMO-40 delivers discharge capacities of 143.1, 134.0, 126.1 and 90.9 mAh g−1, respectively. After cycling for 50 cycles, there is nearly no capacity decay. These better electrochemical performances are believed to be related to the characteristics of the oxygen vacancies. Electrochemical impedance spectroscopy analysis clearly indicates that oxygen vacancies can suppress the charge transfer resistance and increase lithium ions diffusion capability. These findings reveal that oxygen vacancies can be utilized to enhance the electrochemical performances of Li-rich oxide cathode materials.

Construction of MOF-based photocatalysts is promising work due to their considerable active sites and flexible structures. Herein, we present a facile double solvent and in-situ-growth strategy to integrate CdS NPs with MIL-101(Cr) to engineer CdS/MIL-101(Cr) composite photocatalyst. As-prepared CdS/MIL-101(Cr) samples were characterized by TEM, SEM, BET, EPR, XPS, TPC and ESI. CdS/MIL-101(Cr) exhibited remarkable enhanced activity for conversion CO2 to CO under visible light irradiation, and the 36% CdS/MIL-101(Cr) showed the optimal performance in the all samples. The superior activity was attributed to following factors. The strong interaction between CdS and MIL-101(Cr) promoted the separation and transferring of the photogenerated charge carriers. A higher utilization efficiency of photoelectrons could be achieved with the MIL-101(Cr) possessing multiple absorptions and active sites for the photoreduction of CO2. Also, CdS/MIL-101(Cr) provided a special transferring path for photoelectrons, from CdS to MIL-101(Cr), then to photoreduction of CO2, which could be certified by the calculation of energy-level and the survey of O2– of CdS and MIL-101(Cr).

A new binary Mo-based cocatalyst consisting of partially reduced α-MoO3 (MoO3-x) nanoparticles and few-layer MoS2 nanosheets is deposited on AgIn5S8 nano-octahedrons (Octa-AIS) with only (111) facets exposed via an in situ growth process, in which the oxygen-deficient MoO3-x nanoparticles enable facile charge transport due to its high conductivity, while the few-layer MoS2 nanosheets provide more active sites and then excellent catalytic property for H2 evolution. The resultant MoS2-MoO3-x hybrid cocatalyst utilizes the best properties of each component while mitigating their deficiencies, and thus realizes an effective enhancement of visible-light-driven H2 evolution activity on Octa-AIS as compared with the single co-catalyst (such as MoS2, MoO3-x, and even Pt nanoparticles). This study not only presents a rare example of binary Mo-based cocatalyst consisting of MoS2 and MoO3-x components, but also paves a new way to develop an inexpensive photocatalytic system for energy conversion to achieve highly efficient H2 evolution without noble metal-loading.

MnOx/MIL-101 was prepared via incorporating MIL-101, a Cr(III) based MOFs, with MnOx by a photo-deposition method. Multiple techniques XRD, SEM, TEM, XPS, ESR, PL DLS were applied to investigate the structure, photocatalytic activity and mechanism of as-prepared sample. The Cr(III)-oxo clusters in MnOx/MIL-101 and MIL-101 are proposed to be responsible for visible light absorption and also act as an electron trap. MnOx/MIL-101 exhibits much higher photocatalytic activity than pure MIL-101 for degradation of RhB and MB dye under visible light irradiation and the best content of MnOx is 0.050 mol%. This is attributed to the close interaction between MIL-101 and MnOx. The holes can be transferred from MIL-101 to MnOx which is a perfect deriving-hole-types co-catalyst. This not only brings an excellent separation efficiency of the photo-generated carriers, but also another active species •OH, resulting in a higher photocatalytic activity.

A new kind of brookite TiO 2 /g-C 3 N 4 nanocomposite, in which g-C 3 N 4 nanodots (CNDs) with a mean size of ∼2.8 nm are decorated on brookite TiO 2 quasi nanocube (BTN) surfaces (hereafter referred as BTN-CNDs heterojunction), is prepared via a facile calcination process of the mixture of urea and the home-made BTN powders, and then used as visible-light-responsive photocatalyst for CO 2 reduction. Electron microscopy, X-ray powder diffraction (XRD), ultraviolet-visible light (UV-vis) diffuse reflectance absorption spectra (DRS), X-ray photoelectron spectra (XPS) and its valance band (VB) spectra are adopted to investigate the microstructure, composition, energy band structure, and the possible photogenerated electron transfer processes between BTN and CNDs. After optimizing the photocatalytic condition, enhanced visible-light-driven CO 2 -reduction activity and selectivity for CH 4 generation as compared to g-C 3 N 4 and BTN alone are observed, and a photosensitization mechanism is proposed to explain the differences in the photocatalytic performance among g-C 3 N 4 , BTN, and BTN-CNDs. The pronounced CH 4 generation activity and selectivity over BTN-CNDs heterojunction demonstrate a new strategy for improving the interfacial charge transfer and the photocatalytic CO 2 reduction performance though tailoring the microstructures of the semiconductor-based nanocomposites.

Brookite TiO2 quasi nanocubes (BTN) decorated with various Cu nanoclusters (Cu NCs) contents (hereafter referred to as Cu/BTN composite) were synthesized via a facile chemical reduction process by NaBH4. The obtained products and its Cu's existential state were characterized by X-ray diffraction, UV–Vis diffuse reflectance absorption spectroscopy, electron microscopy, X-ray photoelectron spectroscopy and X-ray fluorescence spectroscopy. It was found that the introduction of Cu NCs with small size of ∼1–2 nm on BTN surfaces can improve the photocatalytic H2 production activity, and the maximum photoactivity (225 μmol h−1) for H2 production over 1.0 mol% Cu/BTN composite is similar to that (220 μmol h−1) of the benchmark photocatalyst (P25) under the optimum photoreaction conditions, which is 5.2 times higher than that (42.5 μmol h−1) of the BTN alone. This significant enhancement in the photoactivity of BTN is deemed to result from the metallic Cu NCs with high surface area and dispersion, which favour the co-catalyst functions to cause an effective photogenerated carrier separation in space and an improvement in the photocatalytic activity and stability for H2 production. The present results not only demonstrate the brookite TiO2 would be a potential effective photocatalyst for H2 production, but also provide an inexpensive, efficient and stable means of enhancing light-to-hydrogen energy conversion by using metallic Cu nanoclusters alternative to the commonly used noble metal co-catalyst.

Lithium-rich layered oxide Li[Li0.2Mn0.54Ni0.13Co0.13]O2 coated with V2O5 layers (labeled as LMNCO@V2O5) has been synthesized and its electrochemical properties as cathode material for lithium ion batteries have been measured and compared with pristine Li[Li0.2Mn0.54Ni0.13Co0.13]O2 (labeled as LMNCO) and LMNCO–V2O5 composite. As a lithium ions insertion host material, both the V2O5 in the LMNCO@V2O5 and the LMNCO–V2O5 can reduce the irreversible capacity losses and improve the Coulombic efficiencies of the cathode in the first charge-discharge cycle. However, for improving the cycling stabilities and the high-rate capabilities of the LMNCO, the effects of the V2O5 coating layers in the LMNCO@V2O5 are far beyond the effects of the V2O5 nanoparticles in the LMNCO–V2O5. When charge-discharged galvanostatically at 25 mA g−1 between 2.0 and 4.8 V (vs. Li+/Li), the LMNCO@V2O5 with 3 wt.% V2O5 exhibits a discharge capacity of 279.5 mAh g−1 in the first cycle and maintains a discharge capacity of 269.1 mAh g−1 after 50 cycles, with capacity retention of 96.3%. In contrast, the discharge capacity of the pristine LMNCO changes from 251.2 mAh g−1 in the initial cycle to 202.2 mAh g−1 in the 50th cycle, with capacity retention of 80.2%; and the LMNCO–V2O5 shows the same capacity fading trend as the pristine LMNCO, with no obvious improvement in the capacity retention. At high rate of 1250 mA g−1, the discharge capacity of the LMNCO@V2O5 can reach 113.6 mAh g−1, which is much higher than the capacities that the pristine LMNCO and the LMNCO–V2O5 can reach. Different effects of V2O5 are due to their different roles in the cathode materials. While the V2O5 coating layer in the LMNCO@V2O5 can reduce the charge transfer resistance at the electrode-electrolyte interfaces and improve the transportation of lithium ions among the LMNCO particles, the V2O5 nanoparticles in the LMNCO–V2O5 can only work as a Li+ ions insertion host material.

Industrial wastewater containing heavy metal ions can cover the full pH range according to the manufacturing process. Alkaline wastewater treatment is still a great challenge because Cr6+ therein has a more negative reduction potential (Cr2O72− + 14H+ + 6e− = 2Cr3+ + 7H2O (ECr6+(Cr2O72−/Cr3+) = E θ − RT nF ln [ OH ] − ) than in acid solution, in which it can be easily reduced by numerous reagents. In this study, weakly alkaline Cr6+ solution has been used to simulate weakly alkaline industrial wastewater, and a reagent capable of excellent reduction efficiency therein has been developed. A series of band-gap-energy-adjustable NiS-ZnxCd1-xS composites has been synthesized by a one-pot hydrothermal method. A more negative conduction band position for ZnxCd1-xS has been achieved by doping and changing the amount of Zn2+ ions to ensure a superior photoreduction ability. All modified samples show excellent photocatalytic efficiency. For example, the reduction efficiency of 10%NiS–Zn0.25Cd0.75S sample is threefold higher than that of Zn0.25Cd0.75S and sixfold higher than that of CdS when deployed at a catalytic level for 30 min. Multiple characterization methods have been applied, and the results show that the improved efficiency can be ascribed to intimate contact between Zn0.25Cd0.75S and NiS. Photoluminescence (PL) and photocurrent measurements and electrochemical impedance spectroscopy (EIS) further elucidate the catalytic mechanism and imply an enhanced charge-carrier separation efficiency between Zn0.25Cd0.75S and NiS.

We present one-pot hydrothemal syntheis of SnS2-In2S3 p-n heterostructures for photocatalytic reduction of Cr6+ to Cr3+. The conduction bands of In2S3 and SnS2 serve as the photogenerated electron donors and acceptors, respectively, forming a p-n junction band alignment improving the photogenerated charge separation efficiency. Through a detailed investigation of photocurrent spectra, photoluminescence spectra and electrochemical impedance, the heterojunction formation is shown to enhance the photogenerated charge separation and transport properties. In addition, the analysis of 5,5-Dimethyl-1-pyrroline N-oxide (DMPO) spin trapping electron spin resonance (ESR) spectra and band structure further testify the p-n junction of the composite catalyst that could accelerate the electron transport and change the pathway of photocatalytic process toward Cr6+ reduction. Furthermore, SnS2-In2S3 heterojunction photocatalyst achieved 3 times and 67 times higher efficiency than pure In2S3 and SnS2 photocatalysts under visible light toward Cr6+ reduction. Moreover, the SnS2-In2S3 p-n heterojunction photocatalyst demonstrates Cr6+ removal in a weak alkaline solution, breaking through the challenge of Cr6+ reduction in an alkaline environment.

To enhance the photocatalytic activity, co-catalysts are often utilized to accelerate rate-limited surface reactions. Herein, various amounts of bismuth oxyselenide (Bi2O2Se) (i.e., 5 to 25 wt%) as a novel co-catalyst were deposited on TiO2 nanoparticles for photocatalytic hydrogen evolution reaction. The 15% Bi2O2Se/TiO2 showed the best enhanced hydrogen production rate of 1240.7 μmol h−1g−1, which was about 50 times greater than that of pure TiO2. The SEM, EDX-Mapping and TEM revealed the mechanism of in-growth of Bi2O2Se on the TiO2. Trapping experiment of superoxide free radical (O2−) and transient photocurrent decay measurement also revealed that the recombination of the photogenerated electron–hole was remarkably suppressed in Bi2O2Se/TiO2 compared to pure TiO2. Detailed analysis of XPS, transient photocurrent responses, electrochemical impedance spectroscopy (EIS) and DFT calculations indicated that there is a strong interaction between Bi2O2Se and TiO2, and the electrons of TiO2 can be injected into Bi2O2Se. These findings show the potential of Bi2O2Se as co-catalytic materials and open a new avenue for solar water splitting.

In this paper, a Li2MnSiO4/carbon/graphene (LMS/C/G) composite is synthesized by a facile one-step synthesis method and shows superior high-rate performances as the cathode materials for lithium ion batteries (LIBs). In the LMS/C/G composite, carbon coated Li2MnSiO4 particles, with sizes of 20–30 nm, are uniformly anchored on graphene nanosheets. When assembled as the cathodes of LIBs and charge–discharged at the high rates of 1 C, 2 C, 5 C and 10 C (1 C = 166 mA g−1), the specific discharge capacities of the LMS/C/G composite can reach 210, 181, 143, and 109 mAh g−1, respectively. These electrochemical performances are much better than the performances of the Li2MnSiO4 composites that simply coated with carbon (LMS/C) or merely wrapped by graphene sheets (LMS/G). Electrochemical impedance spectroscopy (EIS) analysis shows that, compared with composites LMS/G and LMS/C, composite LMS/C/G has smaller charge-transfer resistance through the solid-electrolyte interfaces and faster lithium ions diffusion coefficient in the cathode materials. These much improved electronic and ionic conductivities should account for the superior high-rate performances of the LMS/C/G composite.

Lithium-rich layered oxides are promising cathode materials for next-generation lithium-ion batteries (LIBs) used in electric vehicles, due to their high specific capacity over 250 mAh g−1 and high energy density of ∼900 Wh Kg−1. However, the poor rate performance and inferior cycling stability of current lithium-rich layered oxides have greatly hindered their practical applications in vehicular LIBs, mostly due to the ineffectiveness of conventional synthesis methods in controlling the materials size and morphology. Herein, one-dimensional (1D) hierarchical lithium-rich layered oxide (Li1.15Mn0.54Co0.08Ni0.23O2) nanowires were successfully synthesized by a template-assisted molten-salt method that used α-MnO2 nanotubes as both the manganese source and template. The prepared lithium-rich layer oxide nanowires were ∼60–80 nm in diameter and ∼0.5–1 μm in length, and each nanowire was composed of homogeneous and interconnected primary nanoparticles (5–20 nm). Electrochemical characterization showed that the 1D lithium-rich layered oxide nanowires exhibited impressively high-rate performance, long cycle life, and excellent capacity retention as cathode materials for LIBs. For example, the cathode delivered a high initial discharge capacity of 304.5 mAh g−1 with a Columbic efficiency of 81.2%, and maintained a discharge capacity of 253.3 mAh g−1, 241 mAh g−1, 222 mAh g−1, and 203 mAh g−1 after 100 cycles, at 0.5C, 1C, 2C and 5C, respectively. Moreover, at an even high rate of 10C, 20C and 30C, the lithium-rich layered oxide nanowires could still deliver a discharge capacity of 149 mAh g−1, 121 mAh g−1, and 65 mAh g−1 respectively for 1000 cycles, without any capacity decay. Post-cycling structural analysis showed that the 1D nanowire morphology of lithium-rich layered oxide was well preserved after prolonged charge/discharge cycling at 10C for 1000 cycles. The excellent electrochemical performance can be ascribed to the good structural stability of 1D nanowires, primary nanosized particles, high crystallinity of the 1D Li1.15Mn0.54Co0.08Ni0.23O2 nanowires. This work developed a new strategy to synthesize manganese-based cathodes with controlled morphology and high crystallinity by the combination of suitable manganese source and molten salt.

It is well known that different crystal facets of TiO2 have different surface electronic and atomic structures, which can influence the photocatalytic performance, and appropriate noble metal-loading usually improves the photocatalytic activity. Herein we demonstrate that Pt-loading can reverse the photocatalytic activity order of anatase TiO2 {0 0 1} facets (TiO2-0 0 1) and {0 1 0} facets (TiO2-0 1 0) for the photoreduction of CO2 to CH4. This new phenomenon was discussed on the bases of the experimental data including attenuated total reflectance Fourier transform infrared (ATR-IR) spectra, CO2 temperature programmed desorption (CO2-TPD) curves, transmission electron microscopy (TEM) images and time-resolved photoluminescence (PL) spectra. It is found that the higher photocatalytic CO2 reduction activity of TiO2-0 1 0 without Pt-loading can be attributed to its larger CO2 adsorbed amount and longer charge lifetime as compared with TiO2-0 0 1, while the Pt nanoparticles loaded on TiO2-0 0 1 can more efficiently enhance the photoinduced carrier separation efficiency than that on TiO2-0 1 0, and therefore resulting in a photoactivity higher than the Pt-loaded TiO2-0 0 1. The above results provide an important indication about the effects of Pt-loading on the photocatalytic CO2 reduction activity of anatase TiO2 with different exposed facets, and shed light on the fabrication of novel nanostructured photocatalysts through morphological control for high conversion efficiency in the CO2 resource utilization.

A novel graphene-containing Li2FeSiO4 composite (Li2FeSiO4/C/G) has been synthesized successfully which shows superior performance when used as the cathode material for lithium ion batteries. The Li2FeSiO4/C precursor was synthesized via a modified sol-gel method and mixed with graphene oxide nanosheets which were then reduced by annealing to obtain electron conductive graphene. The structure characterizations by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) show that phase-pure Li2FeSiO4/C nanoparticles are mixed homogeneously with graphene nanosheets. When used as the cathode materials for rechargeable lithium ion batteries, the composite Li2FeSiO4/C/G shows superior large capacities and long-time cyclabilities. Specific discharge capacities of 310 mAh g−1, corresponding to 1.86 Li+ ions exchange per Li2FeSiO4 molecule, can be reached at the charging/discharging rate of 0.1 C (1 C = 166 mA g−1). At the high rate of 30 C and 50 C, the composite still shows ∼110 and ∼50 mAh g−1 discharge capacities after 1000 charging-discharging cyclings. These superior–the best up to now–performances of the composite are believed to be the cooperative result of the 3D conducting network, formed by the flexible and planar graphene nanosheets, and the nanoscale sizes of the carbon-coated Li2FeSiO4 particles.

BiOBr-g-C3N4 inorganic–organic composite photocatalysts were synthesized by a one-step chemical bath method at low temperature and characterized by X-ray diffraction patterns (XRD), Fourier transform infrared (FT-IR), thermo gravimetric (TG), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and UV–vis diffuse reflectance spectra (DRS). The BiOBr-g-C3N4 composite showed much higher visible-light-driven (VLD) photocatalytic activity than pure g-C3N4 and BiOBr for rhodamine B (RhB) degradation. The photocatalytic mechanism analysis revealed that the interreaction between BiOBr and g-C3N4 is a kind of facet coupling between BiOBr-{0 0 1} and g-C3N4-{0 0 2}. The active species trapping and quantification experiments indicated that the photoinduced charges transfer between these facets resulted in the efficient charge separation.

Anatase TiO2 crystals with {1 0 1}–{0 0 1} and {0 1 0}–{0 0 1} two facets coexistence were synthesized by (NH4)2TiF6 acting as titanium and fluorine sources and the photocatalytic activity of the samples were investigated. The replacement of {1 0 1} by {0 1 0} facets inhibits the photocatalytic activity of anatase TiO2. The mechanism was examined by photoluminescence spectrum, time-resolved photoluminescence spectra, field emission scanning electron microscope (FESEM) images of selected deposition of Ag, surface atoms structures and electronic band structures of anatase TiO2 facets. The results demonstrated that photoinduced charge transfer properties between {1 0 1} facets and {0 0 1} facets resulted in the efficient charge separation. Replacing {1 0 1} by {0 1 0}, the charge transfer mechanism was altered and the photoinduced electron–hole pairs cannot be separated well. The photocatalytic activity of it has thus been inhibited.

BiOI thin film (BiOI TF) was prepared via a low temperature chemical vapor transport (CVT) route for the first time, and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, fast-Fourier transform pattern and UV–vis diffuse reflectance. As-synthesized BiOI thin film was composed of high symmetrical BiOI nanosheets with dominant exposed {0 0 1} facets. It displayed better photocatalytic activity, durability and selectivity than benchmark P25 TiO 2 thin film and the origin come from the layered structure and good photoelectrochemical performance, CVT immobilization, the 100% terminal oxygen atoms of {0 0 1} facets, respectively. At end, the photocatalytic mechanism with O 2 − production was studied.

article i nfo Article history: Lamellar BiVO4 was prepared through a surfactant-assisted hydrothermal process. The obtained lamellar BiVO4 withmonoclinicphasewasusedasphotocatalystforthereductionofCO2,andexhibitedaselectivemethanolpro- duction undervisible-light irradiation.It isfoundthatthe methanol yield can be significantlyenhancedby adding NaOH solution intheBiVO4suspension because the causticsolution can dissolve moreCO2and the OH − servesas a stronger hole-scavenger as compared to water. The possible mechanism for the selective methanol production from the present photocatalytic CO2 reduction system was also discussed. © 2012 Published by Elsevier B.V.

Magnetic NiFe 2 O 4 nanoparticles were synthesized via a hydrothermal and calcination process. The obtained NiFe 2 O 4 with an average diameter of 17.8 nm and specific surface area of 76.2 m 2 g − 1 is first used as a photocatalyst for hydrogen production, and exhibits an obvious visible-light-driven photoactivity, and therefore is promising in the practical application as a magnetically separable and visible-light-responsive photocatalyst without Pt-loading.

WO 3 with various morphologies and crystal phases were prepared via a hydrothermal process in the presence of different Na 2 SO 4 concentrations. Experimental results indicated that the preferred growth face ((200) crystal plane) of hexagonal WO 3 could adsorb abundant Na + , which induced the WO 3 growing along [001] crystal direction to form nanorods, and hexagonal phase WO 3 nanorods with diameter of 30–150 nm and length of 0.5–5 μm were obtained in the presence of 0.25 M Na 2 SO 4 , while excessive Na 2 SO 4 led to a mixed crystal consisting of cubic H 2 W 2 O 7 and hexagonal WO 3 . The photoactivities for O 2 evolution for various products were investigated by using Fe(NO 3 ) 3 as a sacrificial reagent under visible-light irradiation, and the hexagonal phase WO 3 nanorods show a better photoactivity than the other products with different morphologies and crystal phases due to its fast three-dimensional photogenerated carrier transfer along its special rod-shaped structure.

The CNTs–WO3 hybrid nanostructures were fabricated by solvothermal synthesis. The morphologies, phase structures and optical properties of the nanostructures were investigated by TEM, XRD, UV–vis DRS and XPS respectively. The CNTs–WO3 hybrid nanostructures exist higher photocatalytic activity than pure WO3 nanosheets and the mechanical mixture of WO3 and CNTs for the degradation of methyl blue (MB) under visible light. This is attributed to their large surface area, absorption enhancement in visible light region and effective separation of electrons and holes. The presence of radical scavengers such as KI, Fe3 + and methanol in photocatalytic experiments demonstrates that photogenerated electrons are responsible for the photocatalytic degradation of MB on CNTs–WO3.

Fluoropolymer poly-vinylidene-fluoride modified TiO 2 (PVDF/TiO 2 ) were prepared via a simple chemisorption approach and characterized by thermo gravimetric analyse, transmission electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy and photoluminescence spectra. The modified mechanism and the photocatalytic selectivity of the PVDF/TiO 2 were studied. The existence of Ti-F coordination bond on the interface between TiO 2 and PVDF was confirmed. For the PVDF modification, the photocatalytic degradation (PCD) of cationic dye was greatly enhanced, and the PCD of anionic dye was obviously inhibited. PVDF/TiO 2 shows high photocatalytic selectivity than that of TiO 2 by degrading mixed solution of cationic dyes MB and anionic dyes MO. The selectivity can be tuned by changing the PVDF modification amount.

MWCNT/TiO{sub 2} hybrid nanostructures were prepared via solvothermal synthesis and sol-gel method with benzyl alcohol as a surfactant. As-prepared hybrid materials were characterized by X-ray diffraction, transmission electron microscopy, UV-vis diffuse reflectance spectra and X-ray photoelectron spectroscopy. The results showed that MWCNTs were uniformly decorated with anatase nanocrystals in solvothermal condition, but MWCNTs were embedded in a majority of TiO{sub 2} nanoparticles by sol-gel method. When the weight ratio of MWCNTs to TiO{sub 2} was 20%, MWCNT/TiO{sub 2} hybrid nanostructures prepared by solvothermal synthesis exhibited higher visible-light-driven photocatalytic activity than that prepared by sol-gel method. Post-annealing of MWCNT/TiO{sub 2} nanostructures at 400 deg. C resulted in the formation of the carbonaceous Ti-C bonds on the interface between TiO{sub 2} and MWCNTs, which enhanced the photoabsorbance of the hybrid materials in the visible light region and improved the visible-light degradation efficiency of methylene blue. - Graphical abstract: MWCNT/TiO{sub 2} nanostructures have been prepared by solvothermal method, which exhibited higher visible-light-driven photocatalytic activity than that prepared by sol-gel method. The carbonaceous Ti-C bonds on the interface between TiO{sub 2} and MWCNTs enhanced the photoabsorbance of the hybrid materials in the visible light region. Highlights: > Anatase TiO{sub 2} nanoparticles were anchored onmore » CNTs surface uniformly via solvothermal method {yields} The morphology facilitated the electron transfer between CNTs and TiO{sub 2} {yields} Ti-C bonds extended the absorption of MWCNT/TiO{sub 2} to the whole visible light region. > The hybrid nanostructures showed enhanced visible-light induced photocatalytic activity.« less

In this paper, carbon-supported cobalt–tripyridyl triazine (Co–TPTZ) complexes were synthesized by a simple chemical method, then heat-treated at 600, 700, 800, and 900 °C to optimize their activity for the oxygen reduction reaction (ORR). The resulting catalysts (Co–N/C) all showed strong catalytic activity toward the ORR, but the catalyst heat-treated at 700 °C yielded the best ORR activity. Co–N/C catalysts with several Co loadings – 0.64, 2.0, 2.96, 3.33, 5.28, and 7.18 wt% – were also synthesized and tested for ORR activity. X-ray diffraction and energy dispersive X-ray analysis were used to characterize these catalysts in terms of their structure and composition. To achieve further quantitative evaluation of the catalysts in terms of their ORR kinetics and mechanism, rotating disk electrode and rotating ring-disk electrode techniques were used with the Koutecky–Levich theory to obtain several important kinetic parameters: overall ORR electron transfer number, electron transfer coefficiency in the rate-determining step (RDS), chemical reaction rate constant, electron transfer rate constant in the RDS, exchange current density, and mole percentage of H 2 O 2 produced in the catalyzed ORR. The overall electron transfer number for the catalyzed ORR was determined to be ∼3.5 with 14% H 2 O 2 production, suggesting that the ORR catalyzed by Co–N/C catalysts is a mixture of 2- and 4-electron transfer pathways, dominated by a 4-electron transfer process; based on these measurements, an ORR mechanism is proposed based on the literature and our understanding, to facilitate further investigation. The stability of a Co–N/C catalyst was also tested by fixing a current density to record the change in electrode potential with time. For comparison, two other catalysts, Fe–N/C and TPTZ/C, were also tested for stability under the same conditions as the Co–N/C catalyst. Among these three, the 5 wt% Co–N/C was most stable.

Preferential attachment is an indispensable ingredient of the BA model and its variants. In this paper, we modify the BA model by considering the effect of finite-precision preferential attachment, which exists in many real networks. Finite-precision preferential attachment refers to existing nodes with preferential probability Π varying within a certain interval, which is determined by the value of a given precision, being considered to have an equal chance of capturing a new link. The new model reveals a transition from exponential scaling to a power-law distribution along with the increase of the precision. Epidemic dynamics and immunization on the new network are investigated and it is found that the finite-precision effect should be considered in tasks such as infection rate prediction or immunization policy making.

Hydrogen production over dye-sensitized Pt/P25 under visible-light irradiation was investigated by using methanol or TEOA as an electron donor. Ru 2 (bpy) 4 L 1 –PF 6 shows the best photosensitization due to its largest conjugation system, widest range of visible-light and ‘antenna effect’ among the used three Ru(II)-bipyridyl dyes. Ru 2 (bpy) 4 L 1 –PF 6 loosely linked with TiO 2 also exhibit more steady and higher increases in H 2 evolution upon prolonging the irradiation time than the tightly linked N719. The dynamic equilibrium between the linkage of ground dye and divorce of oxidized dye from TiO 2 can enhance the electron-injection and hinder the backward transfer, and then improve the H 2 evolution efficiency.

H 2 production over dye-sensitized Pt/TiO 2 nanoparticles with mesostructures ( m -TiO 2 ) under visible light ( λ > 420 nm) was investigated by using methanol as electron donors. Experimental results indicate that three types of ruthenium(II) bipyridyl complex dyes (one binuclear Ru, two mononuclear Ru), which can be attached to Pt/ m -TiO 2 with different linkage modes, show different photosensitization effects due to their different coordination circumstances and physicochemical properties. The dye tightly linked with m -TiO 2 has better durability but the lowest H 2 evolution efficiency, whereas the loosely attached dyes possess higher H 2 evolution efficiency and preferable durability. It seems that the dynamic equilibrium between the linkage of the ground state dye with TiO 2 and the divorce of the oxidization state dye from the surfaces plays a crucial role in the photochemical behavior during the photocatalyst sensitization process. It is helpful to improve the H 2 evolution efficiency by enhancing the electron injection and hindering the backward transfer. The binuclear Ru(II) dye shows a better photosensitization in comparison with mononuclear Ru(II) dyes due to its large molecular area, conjugation system, and “antenna effect”, which, in turn, improve the visible light harvesting and electron transfer between the dye molecules and TiO 2 .

The photocatalytic hydrogen production over TiO 2 nanoparticles with mesostructures has been studied using CH 3 OH as a sacrificial reagent. The effects of the calcination temperature, Pt-loading, amount of TiO 2 and methanol as well as irradiation time on the H 2 evolution rate were investigated in detail. The results indicated that the as-synthesized TiO 2 nanoparticles without calcination, having a large specific surface area ( 438 m 2 / g ) and small crystallite size (2.3 nm) dispersed among the amorphous mesoporous domains, exhibited the best photocatalytic activity for H 2 production compared with the samples calcined at different temperatures and the commercial photocatalyst P25 (Degussa, Germany) under the same photoreaction conditions. The presence of mesostructured TiO 2 nanoparticles with a uniform dispersion of the co-catalyst (Pt) has resulted in an effective, faster charge separation, which, in turn, leads to a higher photocatalytic activity for H 2 production.

CdS/Rectorite nanocomposites were prepared through hydrothermal method by using Cd[NH2CSNH2]2Ac2 complex as precursor of CdS which was derived from cadmium acetate and thiourea. The obtained nanocomposites were characterized by X-ray diffraction (XRD), Fourier transfer infrared spectra (FTIR), diffusion reflection spectra (DRS), transmission electron microscopy (TEM) and the selected area electron diffraction (SAED) patterns. Experimental results indicate that CdS exist in at least three forms: CdS adsorbed at surface, CdS pillared in montmorillonite-like layers of Rectorite and CdS pillared in the new layered structure formed during the hydrothermal process. Those CdS crystals are hexagonal symmetry. The photoactivity and photostability of the obtained CdS/Rectorite nanocomposites are improved significantly compared to that of the reference Rectorite and pure CdS.

A novel photodegradable polystyrene-grafted-TiO 2 (PS- g -TiO 2 ) nanocomposite was prepared by embedding the grafted-TiO 2 into the commercial polystyrene. Solid-phase photocatalytic degradation of the PS- g -TiO 2 nanocomposite was carried out in ambient air at room temperature under ultraviolet lamp and/or sunlight irradiation. The properties of composite film were compared with those of the pure PS film by methods such as weight loss measurement, scanning electron microscope (SEM), gel permeation chromatogram (GPC), X-ray photoelectron spectroscopy (XPS), FT-IR spectroscopy, and UV–vis spectroscopy. The results show that the photo-induced degradation of PS- g -TiO 2 composite film is significantly higher than that of pure PS film. The weight loss of composite film reached 31.9%, average molecular weight ( M w ) of composite film decreased by 53.1%, and the number average molecular weight ( M n ) decreased by 73.2% after 396 h of UV-light irradiation. FT-IR analysis and weight loss indicated that the benzene rings in PS-matrix of composite film were cleaved during UV-light irradiation. The photocatalytic degradation mechanism of the films is briefly discussed.

A high-surface-area nanocrystalline TiO2 films were successfully prepared from two kinds of easy-reaggregation primary nanoparticles with the mean size of 26 nm in ethanol solution by a novel technique of quickly volatilizing solvent to fix the nanoparticles. Structure and properties of the films were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The results show that the mean size of nanoparticles does not change with heat-treatment at 450 °C and the roughness factor about 86 and 80 was obtained for 1 μm thickness films. A roughness factor of 82 was found for the commercial P25 TiO2 films with the mean size of 36 nm and the same thickness. The electrochemical properties of the bare interfaces of the TiO2 film electrodes in propylene carbonate (PC) containing 0.05 M tetrabutyl ammonium bromide (TBAB) was also measured and show that the electroactive of the TiO2(I) film is similar to P25. Moreover, this method is adapted to prepare nanostructural films using other materials and smaller primary nanoparticles for dye-sensitized nanocrystalline solar cells.

A new kind of photodegradable polystyrene (PS)–TiO 2 nanocomposite film was synthesized. The TiO 2 nanoparticles were first modified by grafting polymer on its surface (G-TiO 2 ), and then the PS–G-TiO 2 composite films were formed through polymerization. The photocatalytic degradation of the composite films was investigated. The as-prepared films were characterized by scanning electron microscope (SEM), gel permeation chromatogram (GPC), FT-IR and UV-Vis spectroscopy, and the photoinduced weight-loss. The results show that PS–G-TiO 2 nanocomposite films could be efficiently photocatalytically degraded under UV illumination in air. The weight-loss of the PS–G-TiO 2 film reached 29%; the average molecular weight reduced to 1/4 of the original molecular weight under UV-light irradiation for 300 h, implying that some benzene rings had been cleaved. The photocatalytic degradation mechanism of the films is briefly discussed.

Different concentrations of Pr 3+ /Yb 3+ -codoped ZBLAPN glasses (the base composition was 52.4ZrF 4 –19.6BaF 2 –3.5LaF 3 –3AlF 3 –4.5PbF 2 –17NaF in mol%) were prepared and thermal stability was studied for the 52.4ZrF 4 –(19.6– x BaF 2 )–2.2LaF 3 –3AlF 3 –17NaF–1.3YbF 3 – x PbF 2 ( x =4%, 4.5%, 7.5%, 9.5% in mol%) with 1000 ppm Pr 3+ glasses. The absorption spectra were measured and fluorescent properties were calculated using the Judd–Ofelt theory. The energy transfer rates between Pr 3+ and Yb 3+ were calculated. It was shown that the use of Yb 3+ intensified the absorption of Pr 3+ .

New oxysulphide glasses involving Sb 2 O 3 , Sb 2 S 3 and M x S(M = K, Na, Zn), which have different properties from classical oxide glasses and pure chalcogenides glasses, have been prepared. Glass-forming regions are given for the Sb 2 O 3 -Sb 2 S 3 , Sb 2 O 3 -MxS binary systems and ternary systems. These glasses are easy to prepare and chemically stable. The thermal and optical properties of the glasses have been measured and compared with Sb 2 O 3 glass and Sb 2 O 3 -PbCl 2 glass. The oxysulphide glasses are transparent from 0.7 μm to 7.0 μm and T c , crystallization temperatures, T g , glass transition temperatures, ΔT(T c -T g ) > 90°C.

New chalcohalide glasses involving Sb 2 S 3 and MXn have been prepared. Glass-forming regions have been shown in the Sb 2 S 3 -MXn binary systems and Sb 2 S 3 -LiF-NaBr, Sb 2 S 3 -LiF-CaCl 2 ternary systems. These glasses are easy to prepare and chemically stable. Depending on the composition, the glass transition temperature, T g , is between 218 and 230°C, the crystallization temperature, T c , is between 270 and 330°C and the difference T c - T g is between 50 and 90°C, permitting the preparation of preforms of considerable size. These glasses are not transparent in the visible range. The infrared transparent wavelength extends up to about 7.5 μm. These glasses are potential condidates for IR transparent glass around 3–7 μm. The value of σ(100–200°C) of the glasses is about 10 −5 Ω −1 cm −1 .

A method is described for removing trace metals (Fe, Co, Ni, Cu) from ZrOCl2 aqueous solution by simultaneous solvent extraction. The system involving methyl isobutyl ketone (MIBK) as solvent, and ammonium pyrrolidine dithiocarbonate or diethyldithiocarbonate as chelating agent has been researched. The effect of matrix concentration and extraction pH are discussed. The trace metals in a purified ZrOCl2 sample were determined by GFAAS and the results indicate that the Fe content is below 10 ppb, while Co, Ni and Cu contents are each below 5 ppb.