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Engineering the crystal facets and the proportion of edge and corner atoms of brookite TiO2 to expose more coordinatively unsaturated (cus) atoms and open-coordinated sites is of significant importance in boosting the loaded metal nanoparticle (NP) efficiency in heterogeneous catalysis, but suffering tremendous challenge owing to the low structural symmetry and thermodynamic metastability of brookite TiO2. Herein, we prepared brookite TiO2 with nanoflower (NF), nanorod (NR), and nanosheet (NS) shapes, which increased in the catalytically active cus Ti atoms on high-energy facets and the open-coordinated sites on edge and corner atoms. These increments were found to boost the loaded Ru NPs efficiency in selective hydrogenation of benzene to cyclohexene both in activity and selectivity. Combined with comprehensive characterizations, the increased turnover frequency of benzene was ascribed to the increment in the amount and strength of benzene adsorbed on the above catalytically active sites of brookite TiO2, which reacted with spillover hydrogen (Hso) dissociated from Ru NPs. For the improvement in cyclohexene selectivity, it was speculated to be originated from the elevation of the hydrogenation rate constant ratios of benzene to cyclohexene and cyclohexene to cyclohexane steps and the acceleration of cyclohexene desorption once it is formed on the catalyst by the cus Ti atoms and the open-coordinated sites on brookite TiO2.

It is very attractive to construct 3D integrated enzyme-free electrodes for sensitive and selective glucose sensing. In this paper, a novel 3D integrated electrode based on amorphous Ni-B nanoparticle grown on Ni foams (Ni-B/NF) was presented and used for enzyme-free glucose detection. Ni-B/NF was prepared via a simply and rapid electroless deposition with dipping Ni foams into NiCl2 precursors and NaBH4 reducing solutions alternatively. Electrochemical measurements demonstrate that Ni-B/NF has excellent catalytic activity for glucose oxidation and can be used as an efficient enzyme-free electrochemical sensor, with a short response time less than 10 s, a wide detection range from 5 μM to 2.66 mM, a response sensitivity of 8.25 mA mM −1 cm −2, and a low detection limit of 5 μM (S/N = 3). Moreover, the selectivity and reliability for practical application in blood glucose detection of the as-fabricated sensor were also investigated in detail.

Using P25 TiO2 as the precursor, phase-pure anatase and rutile TiO2 as well as TiO2 with tunable anatase-to-rutile molar ratios (nA/nR) were prepared via a facile “selective chemical dissolution” approach. The Ru/TiO2 catalysts were then synthesized and comprehensively characterized by spectroscopic techniques and transmission electron microscopy. It is confirmed that these catalysts possessed similar physicochemical parameters and hydrophilicity, but different Ru sizes (2.3–4.5 nm). Ru nanoparticles (NPs) supported on TiO2 with nA/nR of 2.66 (Ru/TiO2-1.5%HF) exhibited moderate size of 3.4 nm and electron-deficient state, which was originated from the unique Ru-on-anatase/rutile junction structure. In selective benzene hydrogenation, the turnover frequencies of benzene of the mixed phase TiO2-supported Ru catalysts were similar irrespective of the nA/nR ratios and ranged between phase-pure anatase and rutile TiO2-supported Ru catalysts, which can be ascribed to the size effect of Ru. For the cyclohexene selectivity, Ru NPs supported on TiO2 with nA/nR of 0.88–2.66 exhibited higher S0 (92–95%) than Ru NPs on TiO2 with other nA/nR ratios, in which the Ru/TiO2-1.5%HF catalyst displayed a maximum of 95%. We demonstrated that in addition to the proper Ru size, the electron-deficiency of Ru on the Ru/TiO2-1.5%HF catalyst contributed greatly to the highest selectivity since it can promote the desorption of cyclohexene to avoid suffering over-hydrogenation.

Support facet effect of supported metal catalysts for conversion of environmentally toxic feedstock to value-added product is challenging but of significant importance for the understanding of the reaction mechanism and accordingly rational design of newly high-efficient catalytic materials. We report here the effect of the exposed degree of TiO2 {1 0 0} facets, which was facilely tuned by hydrothermal temperature, on benzene selective hydrogenation to cyclohexene over TiO2-supported nanoparticulate Ru catalysts. It is found that the Ru/TiO2 catalyst exposed the most {1 0 0} facets exhibited slightly lower intrinsic activity, but unexpectedly highest selectivity towards cyclohexene (initial selectivity of 93%). A positively linear correlation between the initial selectivity to cyclohexene and the amount of surface OH groups on the Ru/TiO2 catalysts, which was determined by the exposed degree of TiO2 {1 0 0} facets, was identified. This linearity rationalizes the selectivity enhancement of the Ru/TiO2 catalyst exposed more {1 0 0} facets since the surface OH groups functioned in increasing the hydrophilicity of the catalysts, decreasing the type of adsorption sites of cyclohexene, and blocking the chemisorption sites of cyclohexene.

On basis of the galvanic replacement between the previously supported Fe, Ni, Cu, and Co nanoparticles (NPs) and Ru salt followed by acid treatment, a novel strategy was developed for the fabrication of bimetallic Ru–M/TiO2 (M = Fe, Ni, Cu, Co) nanocomposite catalysts. The surface structure, composition, chemical state, and acidic properties of the catalysts were comprehensively investigated by transmission electron microscopy, X-ray photoelectron spectroscopic spectrum, and Fourier transformed infrared spectroscopy of adsorbed pyridine. It is identified that the Ru species on the Ru–M/TiO2 catalysts were electron-deficient owing to the electron-donation from Ru to sacrificial templates. In benzene selective hydrogenation to cyclohexene, the turnover frequencies of benzene on the Ru–Fe/TiO2, Ru–Ni/TiO2, and Ru–Co/TiO2 catalysts are similar and higher than that on the Ru–Cu/TiO2 catalyst, whereas the selectivity to cyclohexene increased in the order of Ru–Fe/TiO2

Pt nanoparticles with size between 2 and 7 nm supported on TiO2 were prepared by a deposition–precipitation method. These catalysts were characterized by nitrogen sorption, powder X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. The effects of Pt loading and reaction conditions on the hydrogenation properties of 3-nitroacetophenone over Pt/TiO2 were investigated. The results show that the catalytic performance of Pt/TiO2 for 3-nitroacetophenone hydrogenation to 3-aminoacetophenone is better than those of Rh/TiO2 and Rh/SiO2. The specific activity of Pt in the Pt/TiO2 for 3-nitroacetophenone hydrogenation increases nearly two times when the Pt loading in the Pt/TiO2 decreases from 1.5 wt% to 0.3 wt%. The selectivity to 3-aminoacetophenone can be up to 100% at complete conversion of 3-nitroacetophenone over the 0.3 wt% Pt/TiO2 even at high temperature and H2 pressure. The high activity and excellent selectivity of the 0.3 wt% Pt/TiO2 are primarily derived from Pt nanoparticles and TiO2 support as well as the interaction between them. The reaction conditions also have a pronounced effect on the catalytic performance. Higher reaction temperature, H2 pressure and polar solvent are favorable for 3-nitroacetophenone hydrogenation to 3-aminoacetophenone over the 0.3 wt% Pt/TiO2.

Nanoporous Co3O4 nanowires (NCoNWs) were synthesized via a two-step process with hydrothermal growth of cobalt nanowires (NWs) precursors and subsequent calcination of corresponding precursors in air. The structures and morphologies of the resulting cobalt NWs precursors and NCoNWs were characterized by X-ray diffraction (XRD), scanning electron microscopic (SEM) and transmission electron microscopic (TEM). NCoNWs show high electrocatalytic activity toward glucose oxidation in alkaline medium and be used for non-enzymatic electrochemical detection of glucose. The sensor displays a high sensitivity of 300.8 μA mM−1 cm−2, a low detection limit of 5 μM (S/N = 3), and a wide linear dynamic range (5.0 × 10−6–5.7 × 10−4 M). Furthermore, the sensor exhibits a high selectivity for glucose against the common interferences including ascorbic acid, uric acid and dopamine which co-exist with glucose in human serum samples.

Direct growth of binary metal oxide nanoarray catalyst on 3D conductive substrate offers electrode materials with high conductivity and large specific surface area, representing an effective strategy to boost the performance of electrocatalyst. In the paper, we report the construction of ZnCo2O4 nanowire arrays supported on carbon cloth (ZnCo2O4 NWAs/CC) and its application for enzyme-free glucose oxidation. ZnCo2O4 NWAs/CC was prepared via a simple hydrothermal synthesis with subsequent calcination process. As an 3D self-supported enzyme-free electrode for glucose sensing, ZnCo2O4 NWAs/CC exhibited excellent catalytic activity with a high sensitivity of 3.88 ​mA ​mM-1 ​cm-2, a wide linear range from 5 ​μM to 0.5 ​mM, and a low detection limit of 2.5 ​μM ​(S/N ​= ​3). Moreover, the proposed sensor shows high selectivity and good reliability for real sample analysis.

Anatase TiO 2 crystallites have been prepared by hydrothermal homogeneous precipitation from Ti(SO 4 ) 2 aqueous solution with urea without using any additives. The structural evolution with the calcination temperature of the photocatalyst was studied. The photocatalytic activity of the obtained photocatalysts was investigated using X-3B dye as a model pollutant. The as-prepared anatase TiO 2 crystallites were highly resistant to thermal sintering, and the calcinations up to 800 °C were shown to enhance the crystallinity of the anatase phase without any rutile phase, which is attributed to the protection of traces of sulfate ions that are produced during the precipitation of titanium sulfate. The gradually increased photocatalytic activity of the anatase TiO 2 calcined from 110 to 800 °C demonstrated strong dependency on its crystallinity. The anatase TiO 2 calcined at 800 °C afforded the highest photocatalytic activity, which was obviously higher than that of commercial Degussa P25 on the photodegradation of X-3B dye in water under ultraviolet light irradiation, and exhibits much faster sedimentability.

One-dimensional (1D) nanobelts of several hundred micrometers in length, several hundred nanometers in width and several hundred nanometers in height are obtained by direct mixing of ortho-phenylenediamine (oPD) and FeCl3 aqueous solution at room temperature. The nanobelts were characterized by elemental analysis, liquid chromatography/mass spectrometry (LC/MS), NMR (1H and 13C), FT-IR, UV–vis, thermogravimetric (TG) and conductivity measurement. The nanobelts are identified as 2,3-diaminophenazine assemblies. The formation of the nanobelts involves two stages: (1) oxidation of oPD by FeCl3, yielding individual 2,3-diaminophenazine molecules; and (2) self-assembly of the 2,3-diaminophenazine, forming the 1D nanobelts. The nanobelts exhibit fairly high thermal stability and show conductivity at the level of semiconductors.

A highly active and selective K-Pd/MnOx-ZrO2-ZnO catalyst for the one-step synthesis of 2-pentanone from ethanol is described. The possible reaction pathways for ethanol reaction over K-Pd/MnOx-ZrO2-ZnO catalyst were investigated by means of TPSR, CO2- and NH3-TPD techniques. The reactions were performed in a fixed bed continuous flow reactor. Complete conversion with high selectivity for 2-pentanone, was observed under 370 similar to 390degreesC, 2 similar to 4 MPa, GHSV = 8000 similar to 10,000 h(-1) and LHSV < 1.25 h(-1) conditions. Ethanol reactions over K-Pd/MnOx-ZrO2-ZnO catalyst showed that the catalyst could catalyze dehydrogenation. aldol. dehydration and hydrogenation reactions. Both acidic and basic properties are found on the surface of K-Pd/MnOx-ZrO2-ZnO catalyst, whose multifunctionality with the combination of basic, acid and metal sites may be responsible for the efficiency of the K-PdMnOx-ZrO2-ZnO catalyst. (C) 2004 Elsevier B.V. All rights reserved.

The catalytic performances of ZrO2-based catalysts were evaluated for the synthesis of higher alcohols from synthesis gas. The crystal phase structures were characterized by X-ray diffraction (XRD) and UV Raman. The results indicated that ZrO2 and Pd modified ZrO2 catalysts were effective catalysts in the synthesis of ethanol or isobutanol, and their selectivities basically depended on the crystal phase of ZrO2 surface. The ZrO2 with surface tetragonal crystal phase exhibited a high activity to form ethanol, while the ZrO2 with surface monoclinic crystal phase exhibited a high activity to form isobutanol. Temperature-programmed desorption (TPD) experiment indicated that the high activity of isobutanol formation from synthesis gas over monoclinic zirconia was due probably to the strong Lewis acidity of Zr4+ cations and the strong Lewis basicity of O2− anions of coordinative unsaturated Zr4+–O2− pairs on the surface of monoclinic ZrO2.

MnO 2 -doped anatase TiO 2 was prepared by precipitation–hydrothermal crystallization method. The as-prepared MnO 2 -doped anatase TiO 2 has a good thermal stability even after calcination up to temperature as high as 800 °C. With increasing calcination temperature, the photocatalytic activity of the MnO 2 -doped anatase TiO 2 increased gradually. The sample calcined at 800 °C afforded the dramatic photocatalytic activity, which was comparable to that of the Degussa P25 TiO 2 . Compared with the P25 TiO 2 , the particle size of the MnO 2 -doped anatase TiO 2 calcined at 800 °C is big, which is very easy to separate from reaction mixture.

The effect of calcination temperature on the textual structure and catalytic properties of amorphous MnOx for the liquid-phase aerobic oxidation of benzyl alcohol was studied. The amorphous nature of the synthesized MnOx was retained when the calcination temperature was lower than 400°C, and calcination temperatures higher than 500°C led to the transformation of amorphous MnOx to crystalline OMS-2 and Mn 2 O 3 . Catalytic reaction studies revealed that the amorphous MnOx exhibited higher mass specific activity than OMS-2, Mn 2 O 3 , and γ-MnO 2 , and MnO x calcined at 110°C showed the highest activity. An inverse linear correlation between the onset reduction temperature in H 2 -TPR and the mass specific activity of the various manganese oxides was observed. These results suggest that the reducibility of manganese oxide is the key factor responsible for its activity for the aerobic oxidation of benzyl alcohol.

Anatase TiO2 nanocrystallites were prepared from TiCl4 with addition of aqueous ammonia by changing Ti(OH)4 hydrogel into its corresponding alcogel followed by supercritical drying in ethanol medium. The as-prepared TiO2 was characterized by XRD, TG and BET. The results show that the prepared anatase TiO2 has remarkable high thermal stability. The anatase structure of the prepared TiO2 is maintained even after calcination up to temperatures as high as 800 °C. The photocatalytic activity of the prepared TiO2 calcined at 800 °C in degradation of reactive brilliant red X-3B is comparable to commercially available nanosized P25 TiO2.