Pore-Mouth Structure of Highly Agglomerated Detonation Nanodiamonds

Detonation nanodiamond aggregates contain water that is removed by thermal treatments in vacuo, leaving available pores for the adsorption of target molecules. A hard hydrogel of detonation nanodiamonds was thermally treated at 423 K for 2 h, 10 h, and 52 h in vacuo to determine the intensive water adsorption sites and clarify the hygroscopic nature of nanodiamonds. Nanodiamond aggregates heated for long periods in vacuo agglomerate due to the removal of structural water molecules through the shrinkage and/or collapse of the pores. The agglomerated nanodiamond structure that results from long heating periods decreases the nitrogen adsorption but increases the water adsorption by 40%. Nanodiamonds heated for long times possess ultramicropores <0.4 nm in diameter in which only water molecules can be adsorbed, and the characteristic mouth-shaped mesopores adsorb 60% more water than nitrogen. The pore mouth controls the adsorption in the mesopores. Long-term dehydration partially distorts the pore mouth, decreasing the nitrogen adsorption. Furthermore, the nitrogen adsorbed at the pore mouth suppresses additional nitrogen adsorption. Consequently, the mesopores are not fully accessible to nitrogen molecules because the pore entrances are blocked by polar groups. Thus, mildly oxidized detonation nanodiamond particles can show a unique molecular sieving behavior

Alkali Metal Ion Storage of Quinone Molecules Grafted on Single-Walled Carbon Nanotubes at Low Temperature

9,10-Anthraquinone and 9,10-phenanthrenequinone (PhQ) were grafted onto two kinds of single-walled carbon nanotube (SWCNT) samples having different mean tube diameters by diazo-coupling reactions. The structural details of PhQ-grafted SWCNT (PhQ/SWCNT) samples were analyzed by X-ray diffraction and Raman measurements. It was discussed that a few-nanometer-thick layer of polymerized PhQs covers the outside of SWCNT bundles. The obtained PhQ/SWCNT works very well as lithium-ion battery and sodium-ion battery electrodes, not only at room temperature but also at 0 °C. It should be noted that the cycle performance of the PhQ/SWCNT electrode is much better than that of PhQ encapsulated in SWCNT (PhQ@SWCNT). We also calculated molecular base reaction energies by density functional theory calculations to gain a qualitative insight into the observed discharge potentials of the PhQ/SWCNT electrode