Yongheng Zhu

Decoration of ZnO nanowires with Pt nanoparticles and their improved gas sensing and photocatalytic performance

Pt nanoparticles were introduced on the surface of ZnO nanowires using a chemically driven self-assembly method. Through this controllable method, Pt-nanoparticle-functionalized ZnO nanowires (Pt NPs-ZnO NWs) with uniform particle dispersion, tunable Pt particle sizes, and narrow particle size distribution were obtained. Changes in the morphology of the decorative preparation were observed as the amount of linker reagent and the concentration of Pt nanoparticle solution were altered. The as-prepared Pt NPs-ZnO NWs with optimal morphology showed excellent gas sensing and photocatalytic performance. Tuning of the functionalities of photocatalytic and gas sensors can be obtained by tailoring the morphology of Pt NP-ZnO NW composite materials.

Amine-functionalized SBA-15 with uniform morphology and well-defined mesostructure for highly sensitive chemosensors to detect formaldehyde vapor.

Amine-functionalized SBA-15 with uniform morphology and well-defined mesostructure was prepared using a postgrafting route. The morphology, mesostructure, and functionality of the materials were characterized by scanning electron microscopy, transmission electron microscopy, small-angle X-ray scattering, nitrogen adsorption-desorption, Fourier transform infrared spectroscopy, and solid-state nuclear magnetic resonance spectroscopy techniques. The results show that hexagonal lamelliform SBA-15 with a uniform particle size and short vertical channels plays two significant roles in uniformly dispersing amine-functionalizing groups and effectively adjusting the loadings of the functional groups within the mesopore channels. To confirm the potential application of the hybrids in gas sensors, using amine-functionalized SBA-15 as a sensing material and a quartz crystal microbalance as a transducer, a parts per billion level formaldehyde sensor with high sensitivity (response time about 11 s, recovery time about 15 s) and good chemoselectivity was achieved. This material holds great potential in the area of rapid, sensitive, and highly convenient formaldehyde detection.

Enhanced gas sensing by assembling Pd nanoparticles onto the surface of SnO2 nanowires

SnO(2) nanowires with an average 0.6 microm in length and about 25 nm in diameter were prepared by a hydrothermal method. The sensors were fabricated using SnO(2) nanowires assembled with Pd nanocrystals. The sensing properties of the sensors such as selectivity, response-recovery time and stability were tested at 290 degrees C. After assembling Pd nanocrystals onto the surface of SnO(2) nanowires, the gas sensing properties of the sensors toward H(2)S were improved. The sensors based on Pd nanoparticle@SnO(2) nanowires exhibit high stability owing to stable single crystal structure. The mechanism of promoting sensing properties with Pd nanoparticles is discussed.

Fluoroalcohol and fluorinated-phenol derivatives functionalized mesoporous SBA-15 hybrids: high-performance gas sensing toward nerve agent

Two new mesoporous SBA-15/organic hybrids featuring fluoroalcohol and fluorinated-phenol derivatives were successfully synthesized via a co-condensation route. Hexafluorobisphenol and hexafluoroisopropanol were chosen to graft onto mesostructured silica, respectively. The as-synthesized hybrids preserve their mesoscopic structures with relative large surface areas and pore volume, as confirmed by SAXS, TEM and N2 adsorption–desorption porosimetry. Moreover, FT-IR and solid-state MAS NMR spectroscopy proved covalent anchoring of the organic functional groups onto the SBA-15. In order to confirm the potential application of the hybrids in gas sensing, investigations on the sensing properties toward the nerve agent simulant dimethyl methylphosphonate (DMMP) were carried out by QCM transducer. The QCM sensors based on hybrid materials exhibit excellent sensitivity toward trace DMMP vapour down to 26 ppb. In comparison with pristine SBA-15, the hybrids also show remarkably enhanced selectivity to DMMP due to suitable H-bonding interactions. Therefore, the well-defined mesoscopic porosity of the organic–inorganic hybrids together with the grafted fluoroalcohol and fluorinated-phenol derivatives lead to excellent sensing properties to DMMP vapour, and show great potential in the area of nerve agent detection.

Monodispersed mesoporous SBA-15 with novel morphologies: controllable synthesis and morphology dependence of humidity sensing

Monodispersed mesoporous SBA-15 materials with hexagonal lamelliform, hexagonal prism and snow-like morphologies were controllably synthesized by a facile hydrothermal method. The novel morphology SBA-15 materials were then coated on the quartz crystal micro-balances to construct highly stable and sensitive humidity sensors (response range of humidity: 1–100% RH).