Yuh-Jing Chiou

Shape effects of iron nanowires on hyperthermia treatment

This research discusses the influence ofmorphology of nanomagneticmaterials (one-dimensional iron nanowires and zero-dimensional iron nanoparticles) on heating efficiency of the hyperthermia treatment. One-dimensional iron nanowires, synthesized by reducing method in external magnetic field, are explored in terms of their material properties, magnetic anisotropy, and cytotoxicity of EMT-6 cells. The magnetic anisotropy of an array of nanowires is examined in parallel and perpendicular magnetic fields by VSM. For the magnetic hyperthermia treatment tests, iron nanowires and nanoparticles with different concentrations are heated in alternating magnetic field to measure their actual heating efficiency and SLP heating properties. The shape effects of iron nanomaterials can be revealed from their heating properties. The cytotoxicity of nanowires with different concentrations is measured by its survival rate in EMT-6 with the cells cultivated for 6 and 24 hours.

SYNTHESIS AND ELECTROCATALYSIS APPLICATION OF HYBRID PLATINUM/CERIUM OXIDE/MULTI-WALLED CARBON NANOTUBES

The hybrid nanomaterials of platinum/cerium oxide/multi-walled carbon nanotubes (Pt/CeO2/MWCNTs) are synthesized successfully via impregnation and polyol processes. MWCNTs serve as an excellent supporter where CeO2 nanoparticles are decorated with well-distributed Pt nanoparticles. Images show the average particle size of crystalline Pt and CeO2 on MWCNTs are 3–7 and 20–30 nm, respectively. In electrochemical reaction, the redox peak of Pt/CeO2-700°C/MWCNTs reveals lower potential and higher current density in methanol electro-oxidation than those of other Pt-based ones. The study indicates that the cerium oxide in Pt/CeO2-700°C/MWCNTs catalyst will enhance significantly the oxygen ions transportation between the interface of Pt and MWCNTs to eliminate the CO poison effect on Pt catalyst.

Synthesis and Electrocatalytical Application of Hybrid Pd/Metal Oxides/MWCNTs

The performance of Pd electrocatalysts for formic acid electrooxidation was improved by application of metal oxide-multiwall carbon nanotubes composites as a catalyst support. Hybrid oxides/MWCNTs were synthesized by two different methods: chemical reduction method and impregnation method. Pd based catalysts were synthesized by polyol method on the MWCNTs or oxide/MWCNTs composites. The In2O3 was deposited on MWCNTs by impregnation method (In2O3/MWCNTs-IM support) and in the presence of NaBH4 (In2O3/MWCNTs-NaBH4 support). The physical properties of the Pd/In2O3/MWCNTs-IM, Pd/In2O3/MWCNTs-NaBH4, Pd/SnO2/MWCNTs, and Pd/MWCNTs catalysts were characterized and their electrocatalytical performance in formic acid oxidation was compared. During Pd deposition on In2O3/MWCNTs-NaBH4 support, InPd2 structure was formed as observed by XRD. The electrochemical tests indicate that the two Pd/ In2O3/MWCNTs electrocatalysts have higher electrocatalytic activity than those of Pd/SnO2/MWCNTs and Pd/MWCNTs. The best performance was observed for the catalyst obtained by In2O3 impregnation of MWCNTs denoted by Pd/In2O3/MWCNTs-IM.

Synthesis and Characterization of PANI-MWCNTs Supported Nano Hybrid Electrocatalysts

Among new energy systems, fuel cells are electrochemical devices transforming chemical energy directly into electrical energy. In our previous works, MWCNTs (the multi walled carbon nanotubes) supported palladium anodic electrocatalysts for DFAFCs (direct formic acid fuel cells) have been studied. MWCNTs can be modified by appropriate oxides, for example, cerium oxide, zirconium oxide and N-doped titanium dioxide, to enhance the electrocatalytic performance of the catalysts. But the oxides and the defects of the acid oxidized MWCNTs, denoted as AO-MWCNTs, can cause the electron capture and reduce both the catalyst conductivity and the catalysts activity. In order to improve the conductive properties of the support, in the present work a conductive polymer was introduced to modify the surface of carbon nanotubes. PANI (polyaniline) has a long-chain structure and conjugated structure and exhibits good conductivity, high stability, and is non-toxic. After PANI modification, AO-MWCNTs can provide efficient electronic conduction network. In this study, PANI modified AO-MWCNTs were prepared via polymerization process. AO-MWCNTs were homogeneously coated with PANI to obtain composite with weight ratio 50:50 PANI to MWCNTs. The thickness of the PANI layer was 4-9 nm. It was shown that the photosynthesis process is a better method to reduce Pd on PANI/AO-MWCNTs than by using NaBH4. By adjusting pH value to 9, during preparation of Pd/PANI/AO-MWCNTs composites by X-ray irradiation process, smaller Pd particles were obtained and PANI deprotonation was avoided which explains better activity of this composite in formic acid electro oxidation.

Synthesis and Characterization of Nano-hybrid Noble Metals/N doped TiO 2 /MWCNTs Electrocatalysts

Novel metal catalysts are easily poisoned by CO adsorption or leaching in oxidation of formic acid that leads to decrease the performances of catalyst. To increase the catalyst activity and poison tolerance in fuel cells, novel metal nanoparticles are usually supported on modified support materials to enhance its performance. In this study, TiO2/MWCNTs are synthesized by sol-gel method. Also, ammonium is used to dope nitrogen into TiO2 to modify its electrical and chemical property. MWCNTs, TiO2/MWCNTs and N-doped TiO2/MWCNTs are three supporters using in this study to examine the effects of supporters on the electrocatalytic performance of Pd and AuPd catalysts. The synthesized metal nanoparticles are uniformly dispersed on the surfaces of MWCNTs, TiO2 and N-doped TiO2 modified MWCNTs. The electrochemical analysis illustrate that Pd/N-doped TiO2/MWCNTs (molar ratio of NH4OH:TiO2=4:1) catalyst exhibits higher activity and better stability than that of Pd/MWCNTs either/or Pd/TiO2/MWCNTs catalyst in formic acid electrooxidation. Same results are observed in AuPd series of catalyts. It indicates that suitable N-doping TiO2 improves dramatically on the performance of Pd or AuPd-based catalysts in electrochemical reaction. Thus, hybrid AuPd/N-doped TiO2/MWCNTs (molar ratio of NH4OH:TiO2=4:1) materials have potentially to be used in the direct formic acid fuel cells (DFAFCs) in the future. Keywords—Fuel cells, Formic Acid, Pd, AuPd, N-doped TiO2, catalyst, MWCNTs