Spinel-type cobalt-manganese-based mixed oxide as sacrificial catalyst for the high yield synthesis of homogeneous carbon nanotubes

摘要: Potential applications of carbon nanotubes (CNTs) in very different fields such as electronics, medicine, or catalysis have been widely demonstrated on a laboratory scale. The development CNT-based commercial products now mainly relies CNTs’ ability to also fulfill the expectations an industrial scale and our produce them at reasonable cost. In past, several attractive materials, fullerenes nanodiamonds, lost some their appeal because synthesis is difficult up for technical economical reasons. For multiwalled (MWCNTs), integration depends availability highpurity with high homogeneity size structure relatively low price. To date, high-quality MWCNTs are produced by catalytic chemical vapor deposition (CCVD) using transition metal heterogeneous catalysts. Despite many efforts, yields remain low, best few tens grams per gram catalyst. Purification strong acids therefore necessary remove remaining catalyst, which significantly increases complexity production process. Herein, we demonstrate that spinel-type cobalt– manganese-based mixed oxide unique catalyst MWCNTs. yield typically 2–9 times higher than obtained conventional catalysts, so purification step no longer needed. addition, exceptionally homogeneous diameter, standard deviation being only 4 nm. quality allow for, knowledge, first time become commodity chemical. Co, Mn, Al, Mg nitrate forms were coprecipitated pH 10 sodium hydroxide (see Supporting Information). precipitate was then filtered thoroughly washed distilled water eliminate ions until conductivity washing solution matched freshly water. filtrate subsequently dried air 180 8C 5 h calcined 400 decompose it into corresponding oxide. Finally, its efficiency growing tested reducing diluted hydrogen (50%) exposing ethylene/hydrogen feed 650 2 Information additional details). 179 gCNTg 1 (17900 wt%), previously under similar conditions (Figure 1). Furthermore, residual impurities synthesized material scarce purity close 99.5% carbon, sufficient most applications. Therefore, traditional mineral required, thus rendering overall process safer, greener cheaper. diameter distribution calculated from high-resolution scanning electron microscopy (HRSEM) transmission (HRTEM) images centered 14 nm nm, remarkably narrow. fully character-