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Tungsten carbides microspheres are synthesized by in situ reduction of ammonium met tungstate microspheres (AMT) precursors as a function of reaction time under CO/CO2 mixture atmosphere. The morphology, size and composition of the as-prepared tungsten carbide microspheres are characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Pt nanoparticles with a diameter of 4.6 nm are loaded onto the surface of WC microspheres using a conventional sodium borohydride reduction method. The electro-catalytic activity and stability toward methanol electrooxidation (MOR) are investigated using cyclic voltammetry (CV) and chronoamperometry (CA). The resultant Pt/WCO-6h catalyst exhibits low onset potential and excellent catalytic performances in comparison to the commercial JM Pt/C and Pt/WC-15h catalysts. Further investigation shows that besides the synergistic effect between WC and Pt, the existence of WO2 might also play an important role in improving the electro-catalytic activity, indicating the positive effect of the surface oxide on the activity and stability of Pt/WC catalysts towards MOR.

Hollow tungsten carbide and cobalt spheres (HTCCS) with cobalt concentration of 6% were prepared by spray conversion and reduction carbonization methods. The HTCCS with diameters of about 8–18 μm were covered with 0.3–1.0 μm microporous. The Pd/WC catalyst was prepared through the replacement reaction between Co nanoparticles on the surface of HTCCS and PdCl4. The electro-catalytic performances for formic acid electro-oxidation were investigated by cyclic voltammetry and chronoamperometry. It exhibited the low onset potential, excellent catalytic activity and stability compared with Pd/C due to the larger electrochemical surface area (ECSA) and the synergistic effect between Pd and WC.

Tungsten trioxide (WO3) spheres decorated with nitrogen-doped graphene (NRGO–WO3) were synthesized by applying the spray-drying procedure and characterized for their ability to serve as an electro-catalyst support for formic acid electro-oxidation. A possible mechanism for the formation of NRGO–WO3 was proposed based on the results of tunneling electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Pd nanoparticles with dimensions of 4.8 nm were loaded onto the surface of NRGO–WO3 using a conventional sodium borohydride reduction method. The electrocatalytic performances of Pd/NRGO–WO3 for formic acid oxidation were investigated by using cyclic voltammetry and chronoamperometry. Due to the decrease in the resistance to electron transfer resulting from the modification of N-doped graphene, which produced an excellent electrical conductor, as well as due to the hydrogen spill-over effect, which accelerated the dehydrogenation of formic acid on Pd active sites, a great enhancement of the electrochemical performances was achieved.

Two types of TiO2 nanocrystals, namely {001} plane dominated nanoplates and {101} faceted nanobipyramids prepared by an oleylamine-containing alcohothermal method in the presence or absence of HF, have been used as adsorbents for removal of methyl orange (MO) from water. Transmission electron microscopy investigation, along with X-ray diffraction analysis, reveals that the average width of the nanoplates is about 13 nm with a thickness of ∼4 nm, and the nanobipyramids posses a length in the c-axis of about 18 nm and a central width of about 11 nm. Although the surface area of TiO2 nanoplates and nanobipyramids are, respectively, about 125.5 and 27.6 m2 g−1, the latter exhibits a much better adsorption performance than the former. In the case of 200 ml of MO aqueous solution with an initial concentration of 50 μmol L−1 (pH = 3), the removal efficiency of MO on TiO2 nanobipyramids (40 mg) reaches about 95% within a contact time of 10 min whereas only ∼65% of MO is removed by TiO2 nanoplates after 60 min treatment. Further investigations indicate that this shape-dependent adsorption performance is related to the fact that the existence of fluorine on the surface of the nanoplates is unfavorable for the adsorption of MO and the interaction between MO (through its sulfonate group) and nanoplates is weaker than that between MO and nanobipyramids. The adsorption of oleylamine on the surfaces of nanobipyramids and nanoplates that may affect the interaction between the MO and TiO2 surface has also been discussed based on the experimental results.

Hierarchical hollow tungsten trioxide spheres (HHTTS) were prepared using PbWO4 precursors as sacrificial templates. The HHTTS with diameters of about 2 μm were loosely self-organized from numerous nanoplatelets. Pt nanoparticles with 7 nm were loaded onto the surface of HHTTS using a conventional sodium borohydride reduction method. The electrocatalytic performances for methanol oxidation of Pt/HHTTS were investigated by cyclic voltammetry and chronoamperometry. Due to the large tunnels of hexagonal structure and high porous surface morphology, great enhancement of electrochemical performances is achieved. The Pt/HHTTS catalyst is demonstrated to be a promising anode material for direct methanol fuel cells (DMFC).

TiO2@CNTs nanocomposite was synthetized by a hydrothermal method at 453 K, using titanium tetrachloride as a precursor and nitrified CNTs as a support. The crystal phase, morphology, microstructure and element distribution of the sample were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscope (TEM), and scanning transmission electron microscopy (STEM-Mapping). The photocatalytic activity of the sample was measured by degrading methyl orange under UV illumination. The results showed that the titania particles in the shape of regular polygon decorate on the outer surface of CNTs evenly, and their sizes were about 7-20 nm. Moreover, photocatalytic activity of the nanocomposite was better than that of P25 Degussa and nitrated CNTs followed the apparent pseudo-first-order rate law. These results point out that synergistic effect exists between the titania and the carbon nanotubes in the nanocomposite.

TiO2/Fe2O3 nanocomposite was fabricated by a hydrolysis-precipitation approach, with TiCl4 as precursor and Fe2O3 as support. The crystal phase, diameter and morphology of the sample particle were characterized by X-ray diffraction, transmission electron microscope. The results show that the samples are composed of haematite and rutile. The morphology and diameter of rutile particle, coating effect and weight percentages of haematite and rutile are related to the preparing temperature and molar ratio of Fe/Ti. The photocatalytic activity of the prepared photocatalyst was estimated in an aqueous solution at ambient temperature of 303K. The results imply that the photocatalytic activity of the sample is higher than that of phase pure rutile, related to Fe/Ti molar ratio and its preparing temperature. These results can be attribute to the microsturcture of the sample. A synergistic effect exists between titania and haematite in the nanocomposite.

A systematic comparative study on the natural diamond, the natural diamond treated by heat or irradiation and synthetic diamond prepared by chemical vapor deposition (CVD) or High temperature and high pressure (HTHP) were carried out by UV-Vis-NIR absorption and FTIR spectra. The results showed that: natural diamond, treated natural samples such as irradiated or annealed ones under high temperature and the HTHP synthetic diamond, the reflection coefficient is obviously variation between 200 nm and 1100 nm in UV-Vis-NIR spectra of above samples. In contrast, the reflection coefficient of CVD synthetic diamond is relatively smaller than the former. Infrared spectra showed that synthetic diamonds, especially for CVD synthetic diamonds have no obvious absorption peak between 800 and 1 600 cm(-1). In additional, the results of DiamondView detection are different for different kinds of diamonds. Generally speaking, some CVD synthetic diamonds treated by HTHP appears some parallel dislocation lines, and show light-blue fluorescence. HPHT synthetic diamonds exhibit strong blocky geometrical shapes whereas some natural diamonds exhibit more tree-ring type fluorescence patterns, the color of diamonds' fluorescence image may change after treated by HTHP or irradiation. In a word, in view of the diversity and innovation of the synthesis technologies for diamond, the natural and synthetic diamonds have some similar spectra characteristic in term of UV-Vis-NIR and FTIR spectra, some special natural diamonds without typical spectra characteristic of natural ones need to be further supplemented with DiamondView, photoluminescence spectra and other instruments.

Core–shell WO2/WO3 microspheres were prepared using a phase transformation route. The as-prepared Pt–WO2/WO3 catalyst exhibits excellent activity and stability towards methanol electrooxidation, compared with those of commercial PtRu/C and Pt/h-WO3, due to the decrease of the electron-transfer resistance by the modification of using WO2 as a conductive oxide.

A comparative study on the natural-color golden seawater cultured pearls and the treated-color golden seawater cultured pearls were carried out by UV-Vis reflectance spectra. Furthermore, the frequency variations of v3, v1 , v2 and v4 bands of the aragonites (a crystal form of calcium carbonate) with the positions of nacreous layer and nucleus in natural or treated-color golden-color seawater cultured pearls were firstly systematically measured. The results showed that: (1) based on the results of UV-Vis reflectance spectra of natural or treated-color golden seawater cultured pearls, interestingly, it was firstly found that the natural-color golden one displays slight varied UV-Vis reflection spectra because of its different surface microstructure located on the outer nacreous layer. Meanwhile, according to the characteristic of UV-Vis reflectance spectra of treated-color golden ones, the treated-color ones were firstly classified to four categories. (2) The frequency of v2 band of aragonite in nacreous layer of natural-color or treated-color golden pearls was greater than the other one from theirs corresponding nucleus, namely A clear blue shift was observed in the former. But the other bands were not altered in the positions of nacreous layer and nucleus, and had the same valves with synthetic aragonites. Additionally, the location of absorption bands of aragonite in nacreous layer of natural or treated-color golden pearls had no frequency shift, which indicates that the behavior of color-treating had no effect on the crystal structure of golden pearls.

The title mol-ecule, C(12)H(16)N(2)O(5), adopts a trans configuration with respect to the C=N bond. In the crystal, inter-molecular N-H⋯O hydrogen bonds link the mol-ecules into chains in [001], and weak inter-molecular C-H⋯O inter-actions further link the chains into corrugated layers parallel to the bc plane.

The title compound, C(11)H(15)N(3)O, crystallizes with two independent mol-ecules per asymmetric unit which differ slightly in their side-chain orientations: the C=N-N-C torsion angle is -176.2 (3)° in one of the mol-ecules and -179.83 (3)° in the other. Each independent mol-ecule adopts a trans configuration with respect to the C=N bond. The two independent mol-ecules are related by a pseudo-inversion center and they exist as a N-H⋯O hydrogen-bonded dimer. The dimers are linked into zigzag chains along [100] by C-H⋯O hydrogen bonds.

The mol­ecule of the title compound, C10H12N2O4, adopts a trans configuration with respect to the C=N bond. The dihedral angle between the benzene ring and the methyl hydrazinecarboxyl­ate plane is 3.01 (6)°. An intra­molecular O—H⋯N hydrogen bond is observed. In the crystal, mol­ecules are linked into a two-dimensional network parallel to (10\overline{1}) by O—H⋯O, N—H⋯O and C—H⋯O hydrogen bonds.

In the title mol-ecule, C(11)H(14)N(2)O(3), the acetohydrazide group is planar 0.084 (1) Å and forms a dihedral angle of 19.7 (1)° with the benzene ring. One of the meth-oxy groups is coplanar with the attached benzene ring within 0.052 (3) Å, whereas the other is slightly twisted [C-O-C-C = 6.3 (3)°]. The mol-ecule adopts a trans configuration with respect to the C=N bond. In the crystal, the mol-ecules are linked into chains along the a axis by N-H⋯O hydrogen bonds and the chains are cross-linked into a three-dimensional network by C-H⋯O hydrogen bonds.

In the title compound, C8H10N2O3, the hydrazinecarboxylate group is twisted from the furan ring by 6.98 (17)°. In the crystal, the molecules are linked into one-dimensional chains running along the c axis by N—H...O hydrogen bonds.

The title compound, C(10)H(12)N(2)O(4), adopts a trans configuration with respect to the C=N double bond. The non-H atoms of the mol-ecule are essentially coplanar, with a maximum deviation of 0.015 (2) Å. An intra-molecular O-H⋯N inter-action is observed. In the crystal structure, the mol-ecules are linked into a two-dimensional network parallel to the ac plane by N-H⋯O hydrogen bonds involving the meth-oxy O atom and by two C-H⋯O hydrogen bonds involving the carbonyl O atom. In addition, an intermolecular C-H⋯π inter-action is observed.

The mol-ecule of the title compound, C(12)H(16)N(2)O(5), adopts a trans configuration with respect to the C=N double bond. The dihedral angle between the benzene and hydrazinecarboxylic acid methyl ester planes is 12.55 (7)°. The mol-ecules are linked into a chain along [001] by inter-molecular N-H⋯O hydrogen bonds, and the chains are cross-linked into a two-dimensional zigzag structure by C-H⋯O hydrogen bonds.

The approximately planar molecule of the title compound, C(11)H(15)N(3)O(2), is in an E configuration with respect to the N=C double bond. An inter-molecular N-H⋯O hydrogen bond links the mol-ecules into a one-dimensional chain propagating in the [010] direction.

The asymmetric unit of the title compound, C(10)H(12)N(2)O(3)·2H(2)O, contains two organic mol-ecules with similar conformations and four water mol-ecules. Each organic mol-ecule is close to planar (r.m.s. deviations = 0.035 and 0.108 Å) and adopts a trans conformation with respect to its C=N bond. In the crystal, the components are linked into a three-dimensional network by N-H⋯O, O-H⋯O, O-H⋯N and C-H⋯O hydrogen bonds, some of which are bifurcated. An R(2) (2)(8) loop occurs between adjacent organic mol-ecules.

In the title mol-ecule, C(7)H(8)N(2)O(2), the acetohydrazide group is planar within 0.014 (2) Å and forms a dihedral angle of 5.35 (8)° with the furan ring. The mol-ecule adopts a trans configuration with respect to the C=N bond. In the crystal, molecules are linked into a chain along the a axis by N-H⋯O hydrogen bonds.

The title compound, C10H12N2O3, crystallizes with two independent mol­ecules in the asymmetric unit. The side chains in the two independent mol­ecules have slightly different orientations, with the C=N—N—C torsion angle being 169.19 (14)° in one of the mol­ecules and −179.86 (14)° in the other. Each independent mol­ecule adopts a trans configuration with respect to the C=N bond. In the crystal structure, mol­ecules are linked into chains running along [001] by N—H⋯O, N—H⋯N and C—H⋯O hydrogen bonds. In addition, an inter­molecular C—H⋯π inter­action is observed.

In the title compound, C(9)H(10)N(2)O(3), the Schiff base mol-ecule is approximately planar, the dihedral angle between the benzene ring and the acetohydrazide group (r.m.s. deviation = 0.034 Å) being 8.81 (7)°. An intra-molecular O-H⋯O hydrogen bond is observed. In the crystal, mol-ecules are linked into a three-dimensional network by O-H⋯O, N-H⋯O and C-H⋯O hydrogen bonds.

In the title compound, C(9)H(10)N(2)O(2)·H(2)O, the mol-ecular skeleton of the acetohydrazide mol-ecule is nearly planar [within 0.014 (1) Å]. The mol-ecule adopts a trans configuration with respect to the C=N bond, while the side chain is slightly twisted away from the attached ring, forming a dihedral angle of 9.975 (8)°. The crystal packing exhibits a three-dimensional network composed from alternating acetohydrazide mol-ecules and uncoordinated water mol-ecules, which inter-act via N-H⋯O, O-H⋯O and O-H⋯N hydrogen bonds. A C-H⋯π inter-action is also present.

In the title mol-ecule, C(10)H(12)N(2)O(2), the acetohydrazide group is planar within 0.012 (1) Å and forms a dihedral angle of 5.25 (8)° with the benzene ring. The meth-oxy group is coplanar with the attached benzene ring [C-O-C-C = 0.1 (2)°]. The mol-ecule adopts a trans configuration with respect to the C=N double bond. In the crystal, mol-ecules are linked into centrosymmetric dimers by N-H⋯O hydrogen bonds and these dimers are linked into a ribbon-like structure along [110] by C-H⋯O hydrogen bonds. In addition, an inter-molecular C-H⋯π inter-action is observed.

The title compound, C(7)H(8)N(2)O(3), crystallizes with two independent but essentially identical mol-ecules in the asymmetric unit. Each mol-ecule adopts a trans configuration with respect to the C=N bond. The hydrazinecarboxyl-ate group is twisted from the furan ring by 7.78 (13)° in one mol-ecule and by 7.01 (17)° in the other. In the crystal structure, mol-ecules are linked into chains running along [010] by bifurcated N-H⋯(N,O) and N-H⋯O hydrogen bonds. In addition, weak C-H⋯O inter-actions and an O⋯C short contact [2.896 (3) Å] are observed.

The mol-ecule of the title compound, C(13)H(18)N(2)O(5), adopts a trans configuration with respect to the C=N bond. The dihedral angle between the benzene ring and the hydrazinecarboxylic acid plane is 49.75 (5)° and an intra-molecular C-H⋯O inter-action occurs. In the crystal structure, the mol-ecules are linked into a chain along [010] by N-H⋯O hydrogen bonds, and a C-H⋯π contact further stabilizes the structure.

The mol-ecule of the title compound, C(12)H(16)N(2)O(3), adopts a trans configuration with respect to the C=N bond. The dihedral angle between the benzene ring and the hydrazinecarboxyl-ate plane is 13.82 (6)°. In the crystal structure, mol-ecules are linked into centrosymmetric dimers by N-H⋯O and C-H⋯O hydrogen bonds, and the dimers are linked together by C-H⋯π inter-actions.

The title compound, C10H12N2O3, adopts a trans configuration with respect to the C=N bond. The dihedral angle between the benzene ring and the hydrazine carboxylic acid plane is 8.29 (7)°. Molecules are linked into a three-dimensional network by N—H...O, O—H...O, O—H...N hydrogen bonds and C—H...π interactions.

The molecule of the title compound, C11H14N2O3, adopts a trans configuration with respect to the C=N bond. The dihedral angle between the benzene ring and the hydrazinecarboxylate plane is 12.06 (9)°. Molecules are linked into a one-dimensional network by N—H...O hydrogen bonds and C—H...π interactions. The benzene rings of inversion-related molecules are stacked with their centroids separated by 3.777 (1) Å, indicating π–π interactions.

In the title compound, C4H5ClN3 +·Cl−, the cation is effectively planar and is protonated at the N atom adjacent to the amino group. Four different N—H...Cl hydrogen bonds serve to connect the constituent ions into supramolecular double chains running parallel to the b axis.