Mubdiul Islam Rizu

We report a MoS₂/PtSe₂ heterostructure-based gas sensor for detecting trace levels of NO₂ gas at room temperature. Both MoS₂ and PtSe₂ were synthesized by mechanical exfoliation, and the heterostructure was prepared using deterministic dry transfer method. Comprehensive characterization was performed using optical microscopy, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, high resolution transmission electron microscopy, Raman spectroscopy and atomic force microscopy. The lateral shape of the heterostructure efficiently adsorbed NO₂ molecules. The sensor exhibited limited response and recovery in dark conditions. However, under UV illumination, the sensor showed remarkable response of 2180% and 117% towards 800 ppb and 50 ppb NO₂, respectively, with complete recovery. The theoretical limit of detection was found to be 3 ppb, and the sensitivity towards NO₂ sensing was 3.217% ppb⁻¹, which is noteworthy. Furthermore, the sensor demonstrated distinct selectivity, excellent repeatability and stability. These findings are expected to significantly advance ongoing research on TMDC-based heterostructures for gas sensing application.

Unlike the most used, this study explores the effects of direct and indirect sonication methods on the dispersion and gas sensing performance of MoS₂ nanoflakes. The obtained dispersions are characterized using various techniques, such as field emission scanning electron microscopy, high resolution transmission electron microscopy, atomic force microscopy, dynamic light scattering, and Raman and X-ray diffraction, to evaluate their morphological and structural properties. Gas sensing measurements are conducted using exfoliated MoS₂ on interdigitated electrode structures, and the response to multiple gases is recorded. The sensitivity and selectivity of the sensors are analyzed and compared between the direct and indirect sonication methods. The results demonstrate that both direct and indirect methods lead to the formation of well-dispersed MoS₂ multilayer nanosheets, whereas the indirect approach exhibits a uniform and bigger flake size. Gas sensing experiments reveal that the MoS₂ nanoflakes prepared via indirect sonication have enhanced sensitivity by 17 and 46% toward NO₂ and NH₃ gases, respectively, compared to the ones achieved by the direct sonication method. Both methods demonstrated its selectivity for NO₂ and NH₃ and the preferential temperature to detect NO₂ and NH₃ gas are 50 and 100 °C, respectively. This research contributes to the development of eco-friendly MoS₂-based gas sensors by providing insights into the influence of direct (probe) and indirect (bath) sonication methods on dispersion quality and gas sensing performance. The findings highlight the potential of indirect sonication as a reliable technique for fabricating high-performance MoS₂ gas sensors, opening venues for the design and optimization of eco-friendly sensing platforms for environmental monitoring and industrial applications.

Implantable electrodes represent a groundbreaking advancement in nervous system research, providing a pivotal tool for recording and stimulating human neural activity. This capability is integral for unraveling the intricacies of the nervous system’s functionality and for devising innovative treatments for various neurological disorders. Implantable electrodes offer distinct advantages compared to conventional recording and stimulating neural activity methods. They deliver heightened precision, fewer associated side effects, and the ability to gather data from diverse neural sources. Crucially, the development of implantable electrodes necessitates key attributes: flexibility, stability, and high resolution. Graphene emerges as a highly promising material for fabricating such electrodes due to its exceptional properties. It boasts remarkable flexibility, ensuring seamless integration with the complex and contoured surfaces of neural tissues. Additionally, graphene exhibits low electrical resistance, enabling efficient transmission of neural signals. Its transparency further extends its utility, facilitating compatibility with various imaging techniques and optogenetics. This paper showcases noteworthy endeavors in utilizing graphene in its pure form and as composites to create and deploy implantable devices tailored for neural recordings and stimulations. It underscores the potential for significant advancements in this field. Furthermore, this paper delves into prospective avenues for refining existing graphene-based electrodes, enhancing their suitability for neural recording applications in in vitro and in vivo settings. These future steps promise to revolutionize further our capacity to understand and interact with the neural research landscape.