Fengqiu Tang

Preparation of porous materials with controlled pore size and porosity

Well-defined porous ceramics with controllable pore size and porosity were fabricated via a hetero-coagulation of template/ceramic particle colloidal processing. Monodispersed polymer spheres were used as template and ceramic nanoparticles as inorganic building blocks to create porous structures. The preparation of well-dispersed suspensions of polymers and ceramics is essential for the fabrication of uniformly porous materials. Core-shell composites of polymer/ceramic could be obtained by mixing the oppositely charged two suspensions via electrostatic attraction following by filtration and calcination to produce macroporous ceramic materials. SEM images and pore size distribution results revealed that various materials, such as Al2O3, TiO2 and ZrO2, with ordered and uniform macropores have been obtained by this simple procedure. The pore size could be controlled readily by varying the polymer size and the porosity could be manipulated by modifying the volume ratio of polymer/ceramic particles

A General Single-Source Route for the Preparation of Hollow Nanoporous Metal Oxide Structures†

A hole in one: Hollow nanoporous structures are prepared by controlled decomposition-dissolution. The partial thermal decomposition of transition-metal salts forms a metal oxide shell on the surface of the metal salt particles. Acid washing removes the metal salt cores, resulting in hollow nanoporous metal oxide shells (see picture). This new strategy provides a template-free single-source route to hollow structures.

Cubic CeO2 nanoparticles as mirror-like scattering layers for efficient light harvesting in dye-sensitized solar cells

A new type of bilayered photoanodes with cubic CeO(2) nanoparticles as mirror-like scattering thin layers was prepared via a screen-printing technique for dye-sensitized solar cells (DSSCs). The light harvesting efficiency was significantly enhanced due to the mirror-like light scattering effect, resulting in noticeable ∼17.8% improvement of light-to-electric conversion efficiency.

Photocatalytic water oxidation on F, N co-doped TiO2 with dominant exposed {001} facets under visible light

Visible-light-responsive anatase TiO(2) platelets with dominant {001} facets were prepared via a facile nitridation reaction from a TiOF(2) precursor. The in situ co-doping of N and F in the anatase TiO(2) nanoparticles leads to drastically enhanced absorption and excellent water oxidation performance in the visible light region.

Electrophoretic deposition of aqueous nano-γ-Al2O3 suspensions

The deposits of nano-sized gamma-Al2O3 powders were fabricated via a simple electrophoretic deposition process in aqueous suspensions. Bubble-free deposits of nano-gamma-Al2O3 powders with a uniform microstructure and high green density up to 56.8% were successfully obtained. Some factors that contribute to the deposition characteristics of the EPD in an aqueous suspension are discussed

Electrophoretic deposition of aqueous nano-sized zinc oxide suspensions on a zinc electrode

Electrophoretic deposition (EPD) was used to form ZnO deposits. ZnO with an average particle size of 40 nm was dispersed in water with the addition of an appropriate amount of anionic polyelectrolyte. Uniform and bubble-free ZnO deposits have been obtained via EPD on a zinc anode in an aqueous suspension. The obtained deposits showed good sinterability.

Fabrication of porous ceramics with controlled pore size by colloidal processing

Abstract Well-defined macroporous ceramics consisting of TiO2 and ZrO2 have been fabricated by two methods. One is via a template-assisted colloidal processing technique and the other is via a hetero-coagulation of template/ceramic particle colloidal processing. The former technique is as follows. Close-packed polymer spheres were first prepared asa template using centrifugation or gravitational sedimentation, followed by infiltration with alkoxide precursors. Then the removal of the template beads was achieved by calcination of the organic–inorganic hybrids at appropriate temperatures, yielding well-ordered macroporous ceramics. The latter technique is as follows. Core–shell composites of polymer/ceramic were obtained by mixing the oppositely charged two suspensions via electrostatic attraction following by filtration and calcination to produce macroporous ceramic materials. SEM images revealed that macroporous TiO2 and ZrO2 with ordered and uniform macropores have been obtained by both procedures.

Nano‐ and Microscale Engineering of the Molybdenum Disulfide‐Based Catalysts for Syngas to Ethanol Conversion

Nickel‐promoted MoS2, unsupported catalysts and laponite‐supported alcohol synthesis catalysts were synthesised by using microemulsion (ME) and hydrothermal (HT) methods. Highly ordered sulfide slabs, consisting of up to seven layers, were visible in the TEM images of HT‐based NiMoS2 catalysts. In contrast, disordered sulfide layers were identified in ME‐based NiMoS2 catalysts. High catalytic activity was observed in ME‐based supported (laponite‐supported NiMoS2) and unsupported catalysts. After the CO hydrogenation reaction, the catalysts were characterised by X‐ray photoelectron spectroscopy and inductively coupled plasma–mass spectrometry elemental analyses, which detected a significant sulfur loss in ME‐based NiMoS2 catalysts and minor sulfur loss in HT‐based NiMoS2 catalysts. In addition to the large surface area (120 m2 g−1), disordered sulfide structure, and exposed active sites, ME‐based NiMoS2 catalysts demonstrated higher alcohol selectivity (61 mol %) than HT‐based NiMoS2 catalysts (15 mol %). Correlations between the catalyst morphology, surface active components, and alcohol selectivity are discussed herein.

Preparation of macroporous titania from nanoparticle building blocks and polymer templates

A simple method based on hetero-coagulation for the preparation of ordered macroporous titania using commercial titania nanoparticles as building blocks and polymer spheres as templates is reported. Surface modification plays a key role in the microstructure of the porous titania.

Layer-By-Layer assembled thin films of inorganic nanomaterials: fabrication and photo-electrochemical properties

The sequential Layer-By-Layer (LBL) self-assembly technique is one of the most promising methods for thin film fabrication. Initially demonstrated by multilayer assemblies using polyelectrolytes, this elegant concept of precisely controlling composition, thickness and architecture of the thin films has been rapidly extended to a diverse array of functional materials including low-dimensional inorganic nanomaterials. This review first introduces some fundamental aspects of the LBL assembly technique; followed by representative examples of the LBL assembled multilayer thin films containing nanostructured materials as building blocks. The photochemical and electrochemical properties of such fabricated thin films were briefly reviewed in the second part.