Zhuhong Yang

Stability of Pt nanoparticles and enhanced photocatalytic performance in mesoporous Pt-(anatase/TiO2(B)) nanoarchitecture

A novel metal–semiconductor nanocomposite with stable metal nanoparticles and efficient photocatalytic performance has been prepared. It consists of highly dispersed ∼2 nm platinum (Pt) nanoparticles loaded on mesoporous and bicrystalline TiO2 fibers (Pt/mb-TiO2). Due to the well organized porous Pt/TiO2 nanoarchitecture, rate of photodegradation of CHCl3 was nearly doubled compared to both P25 and Pt/P25. And in photocatalytic production of H2 (with methanol as an electron donor), Pt/mb-TiO2 presented much more stable activity than Pt/P25. In a 20 h H2 production, Pt nanoparticles on P25 agglomerated and grew remarkably from 2.0 ± 0.5 nm to 4.5 ± 2.5 nm, while Pt nanoparticles on mb-TiO2 changed slightly from 2.0 ± 0.5 nm to 2.2 ± 0.5 nm. Moreover, the loss ratio of Pt on P25 is 36%, which is much larger than that of 7% on mb-TiO2. The efficient charge transfer in the interfaces of Pt/TiO2(B) and TiO2(B)/anatase was discussed. We concluded that the high photocatalytic performance of Pt/mb-TiO2 can be attributed to stable Pt nanoparticles supported on the mesoporous masonry frameworks of TiO2 and efficient charge transfer in the interfaces.

CuO/Cu2O porous composites: shape and composition controllable fabrication inherited from metal organic frameworks and further application in CO oxidation

CuO/Cu2O porous composites with adjustable composition and various morphologies, including cube, octahedron, rod and wire, have been successfully achieved. These structures are inherited from metal organic frameworks formed by Cu and trimesic acid and can be regulated under mild conditions. While tested in CO oxidation, these porous composites exhibited a high performance.

Single-crystalline and reactive facets exposed anatase TiO2 nanofibers with enhanced photocatalytic properties

Single-crystalline anatase TiO2 nanofibers with highly reactive {001} facets were synthesized from layered potassium titanate K2Ti2O5via topotactic transformation in ion-exchange and dehydration. The cuboid fibers showed one-dimensional (1-D) orientation in the [010] direction and {001} as well as {100} facets enclosing along the longitudinal dimension. The structural evolution was deduced from XRD, SEM and TEM characterizations, which revealed that the highly reactive {001} facets were derived from the interlayer splitting and exfoliation of the layered precursors in a surfactant-free way. Photoluminescence (PL) measurements witnessed the efficient separation and transfer of photoinduced charge carriers in the single-crystalline and reactive facets enclosed TiO2 nanofibers. Sequently, highly efficient photocatalytic property of the nanofibers was demonstrated by phenol degradation and H2 evolution. Phenol degradation rate of nanofibers is 2.7 times of the irregular-shaped nanoparticle counterparts with the same crystal phase and similar specific surface area. In photocatalytic evolution of H2, nanofibers presented much higher and more stable activity than both nanoparticle counterparts and P25 benchmark. Charge carrier highways provided by single-crystalline 1-D structures and efficient surface reactivity offered by exposed facets are the two key factors for the enhanced properties.

Synthesis, Features, and Applications of Mesoporous Titania with TiO2(B)

The mesoporous titania with TiO2(B) (mt-TiO2(B)), which has a lattice-matched core-shell crystalline structure with a thin TiO2(B) phase sheathing an anatase core, was synthesized from potassium titanate (K2Ti2O5) by hydration, ion exchange, and calcination. TiO2(B) is a crystalline form of titania with a looser structure than anatase and rutile. Its synthesis, structure, and functions are reviewed. It has all the features of a large specific surface area with a mesoporous architecture, pore wall of high crystallinity and high thermostability. Nanoparticles of noble metals in this mesoporous structured titania are stable. Its potential industrial applications include photocatalysis, oil hydrorefining, and use as a drug carrier, solid acid catalyst, and electrode material. A pilot plant to prepare this unique multifunctional titania material at low cost has been established with a production capacity of 20 tons per year.

A simple approach to mesoporous fibrous titania from potassium dititanate

A new approach is developed to synthesize mesoporous fibrous titania from the sintered product of K(2)Ti(2)O(5), which involves a novel hydrolytic reaction for the formation of potassium-rich nanophase and the generation of an amorphous intermediate.

Carbon-protected Au nanoparticles supported on mesoporous TiO2 for catalytic reduction of p-nitrophenol

With the introduction of carbon on Au/TiO2, the reaction rate of C/Au/TiO2 increased by 29% and the stability was enhanced by about 3 times more than Au/TiO2 in the p-nitrophenol reduction reaction. Carbon species enhanced the stability of Au nanoparticles and also increase the organic reactants adsorptive ability.

Black TiO2(B)/anatase bicrystalline TiO2–x nanofibers with enhanced photocatalytic performance

Black TiO2(B)/anatase bicrystalline TiO2–x nanofibers were synthesized from a porous titanate derivative by calcination in H2, and were characterized using field-emission scanning electron microscopy, Raman spectroscopy, N2 adsorption-desorption analysis, X-ray photoelectron spectroscopy, thermogravimetric analysis, ultraviolet-visible diffuse reflection spectroscopy and photoluminescence measurements. Characterization results showed that no Ti3+ was present on the surface of black bicrystalline TiO2–x and oxygen vacancies were distributed in the bulk of both TiO2(B) and anatase phases. The O/Ti atom stoichiometric ratio of black bicrystalline TiO2–x was estimated to be 1.97 from the difference of mass loss between black bicrystalline TiO2–x and white bicrystalline TiO2 without oxygen vacancies. The photocatalytic activity of black bicrystalline TiO2–x was 4.2 times higher than that of white bicrystalline TiO2 and 10.5 times higher than that of anatase TiO2. The high photocatalytic activity of black bicrystalline TiO2–x was attributed to its effective separation of electrons and holes, which may be related to the effects of both bicrystalline structure and oxygen vacancies. Black bicrystalline TiO2–x also exhibited good photocatalytic activity after recycling ten times. The black bicrystalline TiO2–x nanofibers show potential for use in environmental and energy applications.

An Au-Cu Bimetal Catalyst Supported on Mesoporous TiO2 with Stable Catalytic Performance in CO Oxidation

Abstract An Au-Cu bimetal catalyst was prepared by deposition-precipitation (urea) of gold and copper species on mesoporous TiO 2 and activation with H 2 . The sample was characterized by N 2 adsorption/desorption, X-ray diffraction, ultraviolet-visible spectroscopy, and high-resolution transmission electron microscopy. The results showed that the Au and Cu species formed an Au-Cu alloy and were well dispersed on the mesoporous TiO 2 . According to CO oxidation test results, it was found that the catalytic activity of gold was enhanced by copper. The Au-Cu bimetal catalyst supported on mesoporous TiO 2 showed better catalytic stability in CO oxidation than the Au catalyst supported on mesoporous TiO 2 and the nonporous TiO 2 -supported catalysts. This may be related to the effects of Au-Cu alloying and the mesostructure of TiO 2 .

Review on heat-utilization processes and heat-exchange equipment in biogas engineering

With the increasing demand for environmental protection and renewable energy, bioenergy technology has been attracting considerable attention. Anaerobic digestion (AD) is the process to convert the ...

Thermal Stability of Gold Catalyst Supported on Mesoporous Titania Nanofibers

By deposition-precipitation with urea method, gold was loaded on mesoporous TiO2 whisker, which was prepared from a potassium titanate whisker precursor through solid phase sintering process. The morphology and structure of these as-prepared catalysts were characterized by N2 adsorption-desorption, X-ray diffraction, and transmission electron microscopy. The reduction of 4-nitrophenol to 4-aminophenol by NaBH4 was evaluated as a probe reaction. After calcination at high temperature, the activity of the catalysts supported on mesoporous TiO2 nanofiber was well maintained, and the particle size of gold nanoparticles was hardly changed. This might be attributed to the peculiar crystallographic structure and mesoporous nanoarchitecture of the mesoporous TiO2 whisker.