Search

The catalyzed CVD method is considered significant for the production of low cost and high yield carbon nanostructures. In this study, multiwall carbon nanotubes (MWCNTs) were synthesized using a facile and efficient way with the modified CVD method, using Co nanoparticles as the metallic catalysis for MWCNT growth, in a distinct temperature range of 650–750 °C. The structural and magnetic properties of pristine and functionalized MWCNT (p-MWCNT and f-MWCNT) are investigated in the temperature range of 10–300 K. The phase structure of all MWCNT samples was analyzed using various characterization techniques, namely, x-ray diffraction, Raman, and x-ray photoelectron spectroscopy. Scanning electron microscopy and particle size analysis suggested that the diameter of MWCNTs increases with a rise in the growth temperature, but the nanotube density decreases at 750 °C. Temperature-dependent magnetization studies of the p-MWCNT and f-MWCNT samples were investigated using a quantum design physical property measurement system-vibrating sample magnetometer mode. The magnetic properties and the effect of the growth temperature and acid functionalization on the morphology of MWCNT were also investigated. The results revealed that the diamagnetism effect of the graphitic nanotubes is dominating for p-MWCNT, and it reduces for f-MWCNT. A possible explanation for this feature is discussed in detail in the later part of this article. It may be considered that this study, which emerged with different growth temperatures of MWCNTs using a facile method for gaining control over magnetic properties, can be fundamental for further consideration of magnetic MWCNTs for various potential applications. [ABSTRACT FROM AUTHOR]

In response to the urgent need for advanced climate change mitigation tools, this study introduces an innovative CO 2 gas sensor based on p-p-type heterostructures designed for effective operation at room temperature. This sensor represents a significant step forward, utilizing the synergistic effects of p-p heterojunctions to enhance the effective interfacial area, thereby improving sensitivity. The incorporation of CuO nanoparticles and rGO sheets also optimizes gas transport channels, enhancing the sensor's performance. Our CuO/rGO heterostructures, with 5 wt % rGO, have shown a notable maximum response of 39.6-500 ppm of CO 2 at 25 °C, and a low detection limit of 2 ppm, indicating their potential as high-performance, room-temperature CO 2 sensors. The prepared sensor demonstrates long-term stability, maintaining 98% of its initial performance over a 30-day period when tested at 1-day intervals. Additionally, the sensor remains stable under conditions of over 40% relative humidity. Furthermore, a first-principles study provides insights into the interaction mechanisms with CO 2 molecules, enhancing our understanding of the sensor's operation. This research contributes to the development of CO 2 monitoring solutions, offering a practical and cost-effective approach to environmental monitoring in the context of global climate change efforts.