N‐doped carbon nanotube sponges and their excellent lithium storage performances

Preparation, analysis and lithium storage performance of a series of nitrogendoped carbon nanotube sponges (CNX) is presented in this work. The synthesis was performed using an aerosol-assisted chemical vapor deposition (AACVD) in a bi-sprayer system by using various carbon and nitrogen precursors made of mixtures of benzylamine with toluene, urea, pyridine and 1,2-dichlorbenzene, with ferrocene as catalyst. A series of physico-chemical analysis techniques are used to characterize the composition and the morphology of the obtained materials, and a correlation of these with the lithium storage performances is attempted. The samples reveal an interconnected core-shell CNX fiber morphology with a CNT-core surrounded by an amorphous carbon shell. Appealing lithium storage performances are attained, while also considering aspects of safety, low potential, and long-term cycling stability. The best performing sponges display a high specific capacity (223 mAh g−1) when cycled in a practically relevant voltage window (0.01–1V vs. Li), high first cycle (90%) and long-term cycling (99.3%) coulombic efficiencies and excellent capacity retention after 1500 cycles. This study further analyses the interplay between the morphology and the physico-chemistry of nitrogen-doped carbon nanotube materials for Lithium storage and provides guidelines for future developments

Synthesis of ZnMn2O4 Nanoparticles by a Microwave-Assisted Colloidal Method and their Evaluation as a Gas Sensor of Propane and Carbon Monoxide

Spinel-type ZnMn2O4 nanoparticles were synthesized via a simple and inexpensive microwave-assisted colloidal route. Structural studies by X-ray diffraction showed that a spinel crystal phase of ZnMn2O4 was obtained at a calcination temperature of 500 °C, which was confirmed by Raman and UV-vis characterizations. Spinel-type ZnMn2O4 nanoparticles with a size of 41 nm were identified by transmission electron microscopy. Pellet-type sensors were fabricated using ZnMn2O4 nanoparticles as sensing material. Sensing measurements were performed by exposing the sensor to different concentrations of propane or carbon monoxide at temperatures in the range from 100 to 300 °C. Measurements performed at an operating temperature of 300 °C revealed a good response to 500 ppm of propane and 300 ppm of carbon monoxide. Hence, ZnMn2O4 nanoparticles possess a promising potential in the gas sensors field

Synthesis of ZnMn2O4 nanoparticles by a microwave-assisted colloidal method and their evaluation as a gas sensor of propane and carbon monoxide

"Spinel-type ZnMn2O4 nanoparticles were synthesized via a simple and inexpensive microwave-assisted colloidal route. Structural studies by X-ray diffraction showed that a spinel crystal phase of ZnMn2O4 was obtained at a calcination temperature of 500 °C, which was confirmed by Raman and UV-vis characterizations. Spinel-type ZnMn2O4 nanoparticles with a size of 41 nm were identified by transmission electron microscopy. Pellet-type sensors were fabricated using ZnMn2O4 nanoparticles as sensing material. Sensing measurements were performed by exposing the sensor to different concentrations of propane or carbon monoxide at temperatures in the range from 100 to 300 °C. Measurements performed at an operating temperature of 300 °C revealed a good response to 500 ppm of propane and 300 ppm of carbon monoxide. Hence, ZnMn2O4 nanoparticles possess a promising potential in the gas sensors field.