On the atomic and electronic structures of TiO2 catalyst for hydrogen storage by x-ray absorption spectroscopy

WEN YIN CHEN^1*, Chengguang Lang³, Yu-Cheng Huang², Ta Thi Thuy Nga², Yi Jia³, Da-Hua Wei¹, Chung-Li Dong²

¹Graduate Institute of Manufacturing Technology, National Taipei University of Technology, Taipei, Taiwan
²Department of Physics, Tamkang University, Tamsui, Taiwan
³School of Environment and Science, and Queensland Micro- and Nanotechnology Centre, Griffith University, Nathan campus, Brisbane, QLD 4111, Australia

* Presenter:WEN YIN CHEN, email:t110568048@ntut.org.tw

To date, the titanium dioxide is still of great importance for wide range of research and technology in the energy science owing to its mostly available in the earth crust, environmental compatibility, chemical and photostability. Besides, the bandgap of titanium dioxide can be tuned easily through advanced nanoengineering or defect engineering. In this study, the nanostructured titanium dioxides were prepared for hydrogen storage application. The different amount of defects are created in as-made nano-szied TiO2 following different annealing temperatures (200, 300 and 400°C) under hydrogen atmosphere. It is generally accepted that these defects significantly influence its hydrogen storage performance. The crystal structure was determined by the x-ray diffraction, and the x-ray photoelectron spectroscopy was used to study the charge states of Ti and the modification of valence band upon the defect formation. The UV-Vis characterization further confirmed the higher oxygen vacancies can be generated with higher annealed temperature. The structure-correlated hydrogen storage ability is closely related to different means of adsorption of hydrogen in these defective TiO2. Synchrotron x-rays have particular advantages in the characterization of material structures at the atomic or molecular scale. Thus, the in situ x-ray absorption spectroscopy is carried out to visualize how the hydrogen is adsorbed on the defective TiO2 and shed light on the origin of the improved hydrogen storage ability.

Keywords: atomic, molecular, hydrogen storage