C. Angeles Chavez

Bio: C. Angeles Chavez is an academic researcher from Mexican Institute of Petroleum. The author has contributed to research in topics: High-resolution transmission electron microscopy & Nanoparticle. The author has an hindex of 6, co-authored 9 publications receiving 231 citations.

WOx/TiO2 Catalysts via Titania Nanotubes for the Oxidation of Dibenzothiophene

Abstract: WOx/TiO2 catalysts were synthesized by impregnating aqueous (NH4)2WO4 on hydrous titania nanotubes. The materials were annealed in air at 500 °C and characterized by X-ray diffraction (XRD), Raman spectroscopy, high-resolution transmission electron microscopy (HRTEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), and X-ray photoelectron spectroscopy (XPS); their catalytic activity was evaluated in the oxidation reaction of dibenzothiophene (DBT). After annealing at 500 °C, the structure of the support transformed from orthorhombic, with nanotubular morphology, to tetragonal, yielding anatase nanoparticles decorated by tungsten nanoparticles on its surface. During this transformation, the nanotubes released residual Na+ ions from the interlayer space, which reacted with tungstate species to change the W coordination from octahedral to tetrahedral, yielding ≤1 nm Nax(WO4) nanoparticles on the surface of anatase TiO2. These nanoparticles were highly active for the DBT ...

Photovoltaic Conversion Enhancement of CdSe Quantum Dot-Sensitized TiO2 Decorated with Au Nanoparticles and P3OT

Abstract: Novel composite titanium dioxide (TiO2) films of 10 μm thickness were prepared and characterized with an emphasis on evaluating their photovoltaic properties. The films contained 13 nm TiO2 nanocrystals (NCs) with anatase crystalline phase deposited on FTO substrates, composited with CdSe quantum dots (QDs), gold nanoparticles (Au NPs), and poly(3-octylthiophene) (P3OT) in different configurations and combinations. With the introduction of Au NPs or P3OT into the TiO2/QDs films, the photocurrent increased to ∼85% and ∼150%, respectively, while the photoconversion efficiency increased by ∼167% and ∼177%, respectively. An interesting synergistic effect was observed when Au NPs and P3OT were used in conjunction. The configuration of TiO2/Au/QDs/P3OT film exhibited a photocurrent of 906 μA (an enhancement of ∼285%) and a photoconversion efficiency of 0.661% (an enhancement of ∼600%) compared to that of TiO2/QDs films. Such significant enhancement is attributed to the ability of the Au NPs to facilitate charge...

One-dimensional titanium dioxide nanomaterials: nanotubes.

Abstract: In the present review we try to give a comprehensive and most up to date view to the field, with an emphasis on the currently most investigated anodic TiO2 nanotube arrays. We will first give an overview of different synthesis approaches to produce TiO2 nanotubes and TiO2 nanotube arrays, and then deal with physical and chemical properties of TiO2 nanotubes and techniques to modify them. Finally, we will provide an overview of the most explored and prospective applications of nanotubular TiO2.

Probing the Optical Property and Electronic Structure of TiO2 Nanomaterials for Renewable Energy Applications

Abstract: Probing the Optical Property and Electronic Structure of TiO2 Nanomaterials for Renewable Energy Applications

Catalysis science and technology

Abstract: In early spring 1996 our handbook on science and technology of catalysis will be completed. In order to give all scientists working in the fields of kinetics and homogenous or heterogenous catalysis the possibility to have this detailed treatise of the topic on his or her shelf we decided to offer the whole handbook as a set for a reduced price.

Titanium Dioxide as a Catalyst Support in Heterogeneous Catalysis

Abstract: The lack of stability is a challenge for most heterogeneous catalysts. During operations, the agglomeration of particles may block the active sites of the catalyst, which is believed to contribute to its instability. Recently, titanium oxide (TiO2) was introduced as an alternative support material for heterogeneous catalyst due to the effect of its high surface area stabilizing the catalysts in its mesoporous structure. TiO2 supported metal catalysts have attracted interest due to TiO2 nanoparticles high activity for various reduction and oxidation reactions at low pressures and temperatures. Furthermore, TiO2 was found to be a good metal oxide catalyst support due to the strong metal support interaction, chemical stability, and acid-base property. The aforementioned properties make heterogeneous TiO2 supported catalysts show a high potential in photocatalyst-related applications, electrodes for wet solar cells, synthesis of fine chemicals, and others. This review focuses on TiO2 as a support material for heterogeneous catalysts and its potential applications.

Highly Dispersed CeO2 on TiO2 Nanotube: A Synergistic Nanocomposite with Superior Peroxidase-Like Activity

Abstract: In this report, a novel nanocomposite of highly dispersed CeO2 on a TiO2 nanotube was designed and proposed as a peroxidase-like mimic. The best peroxidase-like activity was obtained for the CeO2/nanotube-TiO2 when the molar ratio of Ce/Ti was 0.1, which was much higher than that for CeO2/nanowire-TiO2, CeO2/nanorod-TiO2, or CeO2/nanoparticle-TiO2 with a similar molar ratio of Ce/Ti. Moreover, in comparison with other nanomaterial based peroxidase mimics, CeO2/nanotube-TiO2 nanocomposites exhibited higher affinity to H2O2 and 3,3′,5,5′-tetramethylbenzidine (TMB). Kinetic analysis indicated that the catalytic behavior was in accordance with typical Michaelis–Menten kinetics. Ce3+ sites were confirmed as the catalytic active sites for the catalytic reaction. The first interaction of surface CeO2 with H2O2 chemically changed the surface state of CeO2 by transforming Ce3+ sites into surface peroxide species causing adsorbed TMB oxidation. Compared with CeO2/nanowire-TiO2, CeO2/nanorod-TiO2, and CeO2/nanoparti...