Beamlines at Siam photon laboratory

โครงการหนึ่งอาจารย์หนึ่งผลงา

Determination of energy levels at the interface between O2 plasma treated ITO/P3HT : PCBM and PEDOT : PSS/P3HT : PCBM using angular-resolved x-ray and ultraviolet photoelectron spectroscopy

10.1088/0022-3727/47/5/055109Journal of Physics D: Applied Physics475055109-05510

Physical Origin of Diminishing Photocatalytic Efficiency for Recycled TiO2 Nanotubes and Ag-Loaded TiO2 Nanotubes in Organic Aqueous Solution

Arrays of titania nanotubes (TiO2NTs) were developed by electrochemical anodization and doped with silver on their surface by photodeposition to achieve TiO2NTs/Ag. It is found that only anatase TiO2NTs were formed, with the preferential growth direction perpendicular to the titanium substrate, and with the length and diameter of ~2 µm and 90–120 nm, respectively. The presence of Ag on the surface of TiO2NTs was also confirmed. The TiO2NTs and TiO2NTs/Ag were used as photocatalysts to decolorize the methylene blue (MB) aqueous solution. The photodegradation efficiency (PDE) is as high as 83% for TiO2NTs and 98% for TiO2NTs/Ag photocatalysts. This work focused on the investigation of the stability and recyclability of these photocatalysts in terms of efficiency and its physical origin by surface analysis using X-ray photoelectron spectroscopy (XPS). It is found that PDE diminishes from 83% to 76% in TiO2NTs upon eight recycling runs and from 98% to 80% in TiO2NTs/Ag upon six recycling runs. The XPS analysis revealed that the physical origin of diminishing efficiency is the carbon contamination on the surface of recycled TiO2NTs and a combination of carbon contamination and Ag leaching in recycled TiO2NTs/Ag

Energy level alignment of blended organic semiconductors and electrodes at the interface

The energy level alignment of a blended mixture of organic semiconductors is often depicted as having a common vacuum level. However, this is not a universal phenomenon among the vast number of organic semiconductors that currently exist, as in many cases the energy levels align via the Fermi level. In this report, the energy level alignments of the mixtures; poly(9-vinylcarbazole) (PVK) and 2,7-bis(diphenylphosphoryl)-9,9′-spirobifluorene (SPPO13) and poly(3-hexylthiophene-2,5-diyl) (P3HT) and SPPO13, with varying SPPO13 concentrations, are measured. It was found that the blended systems exhibit two different vacuum levels with the dipole between the PVK and SPPO13 increasing with the SPPO13 concentration, whilst the P3HT and SPPO13 vacuum levels only experience a small change. This is attributed to the decreasing electronic screening with increasing SPPO13 concentration. These new observations have an important implication in our understanding of interfacial behaviour for blended systems commonly used in various organic electronic devices

New glass cathode materials for Li-ion battery: Ni-Co doping in Li-B-O based glass

Lithium-borate-based glass co-doped with nickel and cobalt ions was successfully fabricated by a two-step melt quenching method. The relationship between Ni and Co contents in the glasses was investigated, with a focus on their electrochemical properties and battery performance. Cyclic voltammetry was used to pre-investigate the electrochemical properties of the glass electrodes. It was found that the specific capacitance of all conditions was above 100 F/g. This preliminary study showed that the glass is feasible to use as a Li-ion battery cathode. The Co-rich content sample (NC11) exhibited the highest specific capacity of 380 mAh/g in the first cycle test. However, the specific capacity was dramatically decreased in subsequent cycles due to Li-ion trapping in the glass structure. Additionally, the higher amount of Ni ions in the co-doping Ni/Co-LBO glass enhanced the retention properties. This suggests that Ni-rich content could improve the release of free Li-ions from the host glass structure

A practical carbon dioxide gas sensor using room-temperature hydrogen plasma reduced graphene oxide

10.1016/j.snb.2013.12.017Sensors and Actuators B: Chemical193692-70

The All-Seeing Eye of Resonant Auger Electron Spectroscopy : A Study on Aqueous Solution Using Tender X-rays

X-ray absorption and Auger electron spectroscopies are demonstrated to be powerful tools to unravel the electronic structure of solvated ions. In this work for the first time, we use a combination of these methods in the tender X-ray regime. This allowed us to address electronic transitions from deep core levels, to probe environmental effects, specifically in the bulk of the solution since the created energetic Auger electrons possess large mean free paths, and moreover, to obtain dynamical information about the ultrafast delocalization of the core-excited electron. In the considered exemplary aqueous KCl solution, the solvated isoelectronic K+ and Cl- ions exhibit notably different Auger electron spectra as a function of the photon energy. Differences appear due to dipole-forbidden transitions in aqueous K+ whose occurrence, according to the performed ab initio calculations, becomes possible only in the presence of solvent water molecules