Metal-Assisted Hydrogen Storage on Pt-Decorated Single-Walled Carbon Nanohorns

Published

June 23, 2012

Author(s)

Yun Liu, Craig M. Brown, Dan A. Neumann, David B. Geohegan, Alexander A. Puretzky, Christopher M. Rouleau, Hui Hu, David Styers-Barnett, Pavel O. Krasnov, Boris I. Yakobson

Abstract

Current methods to study the spillover effect in hydrogen storage materials typically must compare the results from a separate reference sample. This makes it difficult to determine with confidence the amount of adsorbed hydrogen only associated with spillover. We propose two methodologies based on inelastic neutron scattering experiments and high pressure gas adsorption experiments to distinguish between hydrogen adsorbed due to physisorption and hydrogen adsorbed through catalytic spillover at room temperature and have used these two methods to study Pt-decorated single-walled carbon nanohorns. The first method uses the quantum rotational transitions of molecular H₂ observed with inelastic neutron scattering as an indication of the amount of molecular hydrogen adsorbed on the surface and in pores of the sample. By monitoring the intensity of the rotational transition peaks through temperature cycling, we find an upper limit of hydrogen adsorption due to spillover of about 0.17 wt% in this material. For the second method, we have used a high-pressure volumetric apparatus to carefully monitor the pressure of hydrogen gas during temperature cycling of a closed system. This allows us to estimate the upper limit of hydrogen adsorption due to the spillover process to be only about 0.08 wt%. In addition to the capability of measuring the small amount of the adsorbed hydrogen due to catalytic spillover, a major advantage of these methods is that they can conclusively observe the hydrogen adsorption due to spillover without relying on the comparison to a reference sample. Given the interest the spillover phenomenon to the hydrogen storage community and our limited understanding of this effect, we anticipate that these methodologies will help to improve the accuracy and repeatability of measurements of hydrogen adsorption due to spillover.

Citation

Carbon

Volume

50

Pub Type

Journals

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Keywords

Inelastic neutron scattering, hydrogen storage, adsorption, spillover, SWNH, carbon nanohorns

Citation

Liu, Y. , Brown, C. , , D. , Newell, D. , , A. , , C. , Hu, H. , Styers-Barnett, D. , , P. and , B. (2012), Metal-Assisted Hydrogen Storage on Pt-Decorated Single-Walled Carbon Nanohorns, Carbon, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=908705 (Accessed December 3, 2024)