Metal-assisted hydrogen storage on Pt-decorated single-walled carbon nanohorns

详细信息    查看全文

• 作者：Yun Liu ; Craig M. Brown ; Dan A. Neumann ; David B. Geohegan ; Alex ; er A. Puretzky ; Christopher M. Rouleau ; Hui Hu ; David Styers-Barnett ; Pavel O. Krasnov ; Boris I. Yakobson
• 刊名：Carbon
• 出版年：2012
• 出版时间：November, 2012
• 年：2012
• 卷：50
• 期：13
• 页码：4953-4964
• 全文大小：1232 K

文摘

The catalytic dissociation of hydrogen molecules by metal nanoparticles and spillover of atomic hydrogen onto various supports is a well-established phenomenon in catalysis. However, the mechanisms by which metal catalyst nanoparticles can assist in enhanced hydrogen storage on high-surface area supports are still under debate. Experimental measurements of metal-assisted hydrogen storage have been hampered by inaccurate estimation of atomically stored hydrogen deduced from comparative measurements between metal-decorated and undecorated samples. Here we report a temperature cycling technique combined with inelastic neutron scattering (INS) measurements of quantum rotational transitions of molecular H₂ to more accurately quantify adsorbed hydrogen aided by catalytic particles using single samples. Temperature cycling measurements on single-wall carbon nanohorns (SWCNHs) decorated with 2-3 nm Pt nanoparticles showed 0.17 % mass fraction of metal-assisted hydrogen storage (at ¡Ö0.5 MPa) at room temperature. Temperature cycling of Pt-decorated SWCNHs using a Sievert¡¯s apparatus also indicated metal-assisted hydrogen adsorption of ¡Ö0.08 % mass fraction at 5 MPa at room temperature. No additional metal-assisted hydrogen storage was observed in SWCNH samples without Pt nanoparticles cycled to room temperature. The possible formation of C-H bonds due to spilled-over atomic hydrogen was also investigated using both INS and density functional theory calculations.