Carbon black (CB), a material consisting of finely divided particles, can be obtained by the partial combustion of heavy petroleum feedstock. The commercial preparation of CB nanoparticles require sophisticated equipment, chemical pre-treatment, and combination of complex separation and purification techniques. CB nanoparticles can also be recovered from scrubbed rubber, but yields are modest and the process is technically complex. Here, we report the development of a simple and inexpensive method for the preparation of CB nanoparticles from waste tires. Under optimal conditions, the yield of recovered CB nanoparticles (∼22 nm) was of approximately 81%; the nanomaterial presents good thermal stability and conductivity, and forms chain-like agglomerates; chemical composition analysis and solubility tests indicates that it is partly oxidized (C, 84.9%; S, 10.21%; O, 4.9%). The product was fully characterized by FTIR, Raman, TGA, BET, SEM and TEM. This preparation method could become a viable alternative to reduce the large amount of waste tires and decreasing their negative environmental impact, producing good quality CB nanoparticles useful for batteries, sensors, electronic devices, catalysis, pigments, concrete, and plastics, among many other applications.
The synthesis of electrochemically active β-Mo 2 C nanoparticles for hydrogen production was achieved by a fast and energy-efficient microwave-assisted carburization process from molybdenum oxides and carbon black. With the use of microwavebased production methods, we aim to reduce the long-time high-temperature treatments and the use of hazardous gases often seen in traditional molybdenum carbide synthesis processes. In our process, carbon black not only serves as a carbon source but also as a susceptor (microwave absorber) and conductive substrate. The irradiation power, reaction time, and Mo:C ratio were optimized to achieve the highest electrocatalytic performance toward hydrogen production in an acidic electrolyte. A complete transformation of MoO 3 to β-Mo 2 C nanoparticles and an additional graphitization of the carbon black matrix were achieved at 1000 W, 600 s, and Mo:C ratio above 1:7.5. Under these conditions, the optimized composite exhibited an excellent HER performance (η 10 = 156 mV, Tafel slope of 53 mV•dec −1 ) and large turnover frequency per active site (3.09 H 2 •s −1 at an overpotential of 200 mV), making it among the most efficient non-noble-metal catalysts. The excellent activity was achieved thanks to the abundance of β-Mo 2 C nanoparticles, the intimate nanoparticle-substrate interface, and enhanced electron transport toward the carbon black matrix. We also investigated the flexibility of the synthesis method by adding additional Fe or V as secondary transition metals, as well as the effect of the substrate.
There are many studies on the synthesis and structure of mesoporous silica, but few reports on mesoporous silica-based electronic devices using planar technology. Fabrication of low-k insulator films from mesoporous silica has been investigated for years. Trapped water is a nuisance for those intending to use mesoporous silica films as low-k materials, but may be beneficial for other applications. In this work, we fabricated Si metal-insulator-semiconductor capacitors (MIS) with a hexagonal mesoporous silica (MCM-41) film as the dielectric and studied their electrical characteristics. We show that water confined within the dielectric is associated with high values of capacitance per unit area (approximately 1 μF cm −2 at 100 Hz) and frequency dispersion of the accumulation capacitance. These devices hold potential for the development of high value MIS capacitors, sensors and biosensors.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.