Sun Hee Choi 교수

The local structure of Fe in Fe−ZSM-5 prepared by solid-state exchange was investigated with XAFS. Fe K-edge spectra were taken at liquid nitrogen temperature for samples with Fe/Al ratios of 0.33, 0.66, and 0.80. The radial structure function (RSF) of He- and CO-pretreated Fe−ZSM-5 shows two main peaks, one at 1.6 Å and the other at 2.5 Å. To interpret the origin of these peaks, RSFs were simulated for a number of mono- and di-iron structures obtained from quantum chemical calculations. By this

Pt NPs were in situ synthesised on poly(sodium styrene sulfonate) functionalized graphene supports (PSS–G) in aqueous solution. We investigate the reduction of graphene oxide, PSS adsorption on reduced graphene, and Pt NP functionalization by X-ray photoelectron spectroscopy (XPS), X-ray absorption fine structure studies (XAFS), Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy and transmission electron microscopy. The as-prepared Pt on PSS–G sample (Pt–PSS–G) was used di

In this study, we present an advanced strategy of low-temperature hydrogen annealing combined with high- temperature quenching in air for activating α-Fe₂O₃ nanorod photoanodes to boost the photoelectrochemical performance. We report that various low-temperature annealing conditions (340, 360, 380, and 400 °C) under hydrogen gas flow convert β-FeOOH into magnetite (Fe₃O₄) as well as introduce Sn⁴⁺ diffusion from FTO substrates to its surface

An MFI zeolite framework containing iron and aluminum has been prepared and characterized by X-ray absorption spectroscopy. Extended X-ray absorption fine structure analysis indicates that in the as-prepared zeolite Fe is present in the framework but migrates to extraframework sites upon thermal activation at elevated temperature. In the absence of framework Al, Fe forms small particles of Fe3O4. When Al is included in the zeolite, extraframework Fe associates with framework Al in a manner ident