Mesoporous binder-free monoliths of few-walled carbon nanotubes by spark plasma sintering

Abstract

porous binder-free monoliths of few-walled carbon nanotubes by spark plasma sintering. Journal of Materials Science, Springer Verlag, 2018Verlag, , vol. 53 (n°5), pp. 3225-3238. 10.1007Verlag, /s10853-017-1784 Open Archive TOULOUSE Archive Ouverte (OATAO) OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. ABSTRACTCarbon nanotubes with few walls (FWCNTs) are prepared by catalytic chemical vapor deposition. Transmission electron microscopy investigations for each sample show the average number of walls (3, 4 and 8) as well as the internal and external diameter distributions. Binder-free FWCNT monoliths are prepared by spark plasma sintering (SPS) at temperatures in the range 1000-1600 °C. A combination of techniques including Raman spectroscopy, scanning-and transmission electron microscopy, electron microdiffraction is used to characterize the samples. Compared to the FWCNT powders, the high temperatures used for SPS favor the elimination of surface defects in CNT walls but also some limited amorphization, without dramatic damage to the CNTs. Increasing the SPS temperatures produces an increase in densification. N 2 adsorption-desorption cycles revealed that the powders and monoliths show microporosity and, mostly, mesoporosity. Some monoliths show a specific surface area equal to about 500 m 2 /g. The 4WCNTs when consolidated into monoliths by SPS at 1000 or 1100 °C are able to retain a high amount of mesoporosity that contributes to a high porous volume of the order of 0.8 cm 3 /g.

Conversion of Secondary C3-C4 Aliphatic Alcohols on Carbon Nanotubes Consolidated by Spark Plasma Sintering

“…Different CNMs were consolidated by SPS [ 26 , 27 , 28 ]. Consolidated CNMs can be used as adsorbents [ 29 ], biocompatible materials [ 30 ], catalysts, catalysts supports [ 31 ] and electrodes in energy storage devices [ 32 ].…”

Spark plasma sintered catalytic nickel–copper alloy and carbon nanotube electrodes for the hydrogen evolution reaction

“…The calculated (BET specific surface area S BET (Fig. 3a and Table S1, ESI †) is 190, 198, 203, 155 and 121 m 2 g À1 for E1, E2, E5, E12 and E20, respectively, compared to 214 m 2 g À1 for the metal-free CNT monolith, 24 reflects the increase in metal content in the sample. This could indicate that the consolidation of the CNT scaffold was unaffected by the presence of the Ni-Cu alloy nanoparticles.…”

“…[29][30][31][32] The relative density of the electrodes is (63 AE 1)%, in good agreement with the values found for CNT monoliths (56-60%). 24 The corresponding volumetric metal loadings are 13.5, 30.8, 63.3, 204.6, and 324.6 mg cm À3 . Hence, this wide range of metal contents will allow the rationalization of the study of textural and electrocatalytic properties.…”

“…The latter are relatively light, show high specific surface area and electrical conductivity and can be shaped into free-standing mesoporous electrodes by SPS. [23][24][25] One of the key advantage of SPS for this work is that it will simultaneously provide the consolidation of the CNT scaffold into an electrode and the in situ reduction of the NiO-CuO precursors into the nanostructured and active metallic alloy of Ni-Cu. The rapidly produced electrodes with tuneable characteristics (surface area, porosity, etc.…”