The 281st MANA & the 122nd ICYS Joint Seminar
Dr. Zoe Schnepp & Dr. Tianyou Zhai
| Date | September 7, Friday |
| Time | 15:30-16:30 |
| Place | #2 Conference Room, 1F, Central Bldg., Sengen Site, NIMS |
Download PDF file for seminar info.
15:30-16:00
One-step route to functional hybrid nanocomposites
Transition metal nitrides and carbides (e.g. WC, Fe3N) are important materials with diverse applications in catalysis, electrochemistry and hard coatings. As catalysts, they are undergoing a recent revival due to the need for catalysts based on earth-abundant elements. They can exhibit noble metal-like behavior and as such have the potential to replace scarce and costly noble metals such as platinum in fuel cell electrodes or as cocatalysts in photocatalytic water splitting. To enhance activity and also prevent sintering it is desirable to produce a composite with a metal oxide support. Further key requirements are small particle size, high interdispersion and good connection between the carbide/nitride and metal oxide particles. However, synthesizing mixed oxide/carbide or oxide/nitride nanocomposites with all these properties presents a considerable challenge. The few existing examples generally require pre-synthesis of one or more oxide phases followed by high-temperature ammonolysis or temperature programmed reduction. This talk will describe a conceptually new approach: in-situ selective carbothermal reduction. This method is the first one-step synthesis of hybrid oxide/nitride or oxide/carbide nanocomposites, e.g. MgO/Fe3C, TiO2/WN. These materials show some promising catalytic properties.
Speaker
Dr. Zoe Schnepp, ICYS-Sengen Researcher, MANA, NIMS
Chair
Dr. Yoshio Sakka, Group Leader, Advanced Ceramicｓ Group, Materials Processing Unit, NIMS
16:00-16:30
One-Dimensional CdS Nanostructures: From Synthesis to Applications
As an important II-VI semiconductor, CdS (with a direct band gap of 2.5 eV) is one of the first semiconductors discovered and is probably ones of the most important electronic and optoelectronic materials with prominent applications in nonlinear optical devices, flat panel displays, light emitting diodes, lasers, logic gates, transistors, etc. It is also a decent active optical wavelength material and electrically driven lasing material, which may find wide applications in telecommunications, data storage, and near-field optical lithography. Compared with ZnO, CdS has the closet fundamental physical properties including crystal structures and lattice constants, and possesses superior properties including narrow bandgap, high transmittance in visible range, low work function, low surface recombination rate, and few oxygen vacancies. However, only little work focuses on CdS nanostructures compared to that of ZnO. Why? I think that there are three main reasons: First, difficulties in fabrication of high-quality structures; Second, poor properties, just a random characterization; Third, few practical applications. Here I will show my recent work to resolve these problems correspondingly, including rational fabrication, correlations between structures and properties, and photodetectors with high performances.
Speaker
Dr. Tianyou Zhai, ICYS-MANA Researcher, NIMS
Chair
Dr. Yoshio Bando, MANA COO, MANA, NIMS