Effect of milling conditions on the purity of hydrogen desorbed from ball-milled graphite

Yinghe Zhang, David Book

    Research output: Contribution to journalArticle

    12 Citations (Scopus)

    Abstract

    During ball milling, graphite can absorb a relatively large amount of hydrogen (7.4 wt %). However, during subsequent heating, hydrogen is usually desorbed together with a small amount of methane. Therefore, there is a need to understand the mechanism of hydrogen sorption. In this work, graphite samples were ball milled in a tungsten carbide pot under 3 bar hydrogen and then characterized by TGA-mass spectrometry, TEM, and Raman spectroscopy. It was found that the optimum milling time was 10 h, resulting in desorption of 5.5 wt % pure hydrogen (using a mass spectrometer) during heating under argon to 990 °C. In samples milled for longer than 10 h the amount of desorbed hydrogen decreased with methane being released in increasing amounts, while the amount of pure desorbed hydrogen was reduced for milling durations less than 10 h. The importance of milling time is discussed in terms of the different reaction steps between carbon and hydrogen atoms, leading to formation of methyl radicals, followed by evolution of methane.

    Original languageEnglish
    Pages (from-to)25285-25289
    Number of pages5
    JournalJournal of Physical Chemistry C
    Volume115
    Issue number51
    DOIs
    Publication statusPublished - 2011 Dec 29

    ASJC Scopus subject areas

    • Physical and Theoretical Chemistry
    • Electronic, Optical and Magnetic Materials
    • Surfaces, Coatings and Films
    • Energy(all)

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