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  • 08월 28일 16시 이후 : 초록수정 불가능, 일정확인 및 검색만 가능

Feasibility of hydrogen storage based on metal-dispersed polymers

2008년 8월 14일 17시 43분 18초
금27D3워 이곳을 클릭하시면 발표코드에 대한 설명을 보실 수 있습니다.
금 09시 : 30분
물리화학 - Workshop on Surface and Interface Physical Chemistry
저자 및
서울대학교 화학생물공부, Korea
Recent density functional theory (DFT) calculations have shown that a multiple number of hydrogen molecules chemisorb by the so-called Kubas interaction on fullerene, carbon nanotube, and various conducting polymers decorated with early transition metals such as Sc, V, and Ti with a binding energy of 0.3-0.5 eV.[1] This opened up a new possibility of using this type of materials as hydrogen storage with a high gravimetric and volumetric storage density at ambient conditions. In order to experimentally verify the Kubas interaction in these adsorption systems and to define unforeseen practical problems in the storage application, we have investigated the interactions of hydrogen with Ti-dispersed polyaniline (PANI) using temperature-programmed desorption (TPD) and Auger electron spectroscopy (AES). While D2 does not adsorb on pristine PANI at 87 K, it readily adsorbs on Ti / PANI to result in broad desorption peak of D2 ranging from 110 to 450 K with a maximum at ~ 250 K. Based on the large peak width and substantial isotope scrambling, we assign the peak to atomically adsorbed D2. Simultaneous desorption of HD and H2 was also observed in the same temperature range. We estimate that only ~ 0.5 D2 per Ti adsorb at saturation and the molecular adsorption energy is less than ~ 0.2 eV, which are much smaller compared with 3.5 D2/Ti adsorbed and 0.35- 0.5 eV, respectively, calculated by Lee et al.[1] The AES spectra of Ti(1 ML)-adsorbed PANI saturated with D2 at 87 K show that 1) the deposited Ti atoms coordinate with –NH and benzene ring carbons, 2) at Ti coverage greater than 2ML phenyl carbons turn into carbide, and 3) small Ti clusters form. We will interpret the TPD and AES results with possible bonding configurations of Ti atoms to explain why the Ti atoms have a limited adsorption capacity toward D2. The limitation of simple DFT calculations for an adsorption system involving a chemical reaction will be addressed and propose better storage materials. [1] Lee, H. K.; Choi, W. I.; Ihm, J. S. Phys. Rev. Lett., 97, 56104 (2006).