One-dimensional nanostructure ZnO nanorods (NRs) with controlled lengths and diameters were synthesized by the growth of colloidal nanoparticles and then characterized by XRD, TEM, Raman, PL and UVâVis. The growth time parameter plays an important role in the formation process of ZnO NRs. The as-prepared nanoparticles has spherical shape with size about 4Â nm, and formed single-crystalline NRs of length up to 150Â nm and 16â20Â nm in diameters. Raman spectra of the as-grown ZnO nanorods revealed the existence of Raman silent modes B1(low) and B1(high) at 273 and 538Â cmâ1 respectively. Photoluminescence (PL) and UVâvisible absorption measurements have been performed at room temperature. The PL spectrum showed that the relative intensity of ultraviolet (UV) and defect bands depend on the length of ZnO nanorods. The peak of photoluminescence of UV band around 395Â nm is strongly enhanced when the length of ZnO nanorods is reduced and the humps around 580Â nm decreases. Keywords: ZnO nanorods, Raman spectroscopy, UVâVis spectroscopy, Photoluminescence spectroscop

This paper reviews the most important sensor-based methods that are commonly utilized for detecting and measuring hydrogen sulfide (H2S) gas. It identifies a quite comprehensive overview related to the toxicity and hazardous effects of H2S gas from an individual and environmental health protection perspective. Furthermore, the description, classification and comparison of the H2S gas sensing technologies are exhibited according to many criteria such as sensing material, working principle, limit of detection, response time, operating range of gas concentrations, sensor stability, sensitivity and selectivity toward H2S. Finally, it identifies the limitations of these sensors, suggests the most probably successful future technologies, and highlights the most promising approaches that have been developed for achieving inexpensive hydrogen sulfide gas sensors which could be employed in widespread miniaturized detectors in the real-world applications.

High-performance, room temperature-based novel sensing materials are one of the frontier research topics in the gas sensing field, and MXenes, a family of emerging 2D layered materials, has gained widespread attention due to their distinctive properties. In this work, we propose a chemiresistive gas sensor made from V₂CT_x MXene-derived, urchin-like V₂O₅ hybrid materials (V₂C/V₂O₅ MXene) for gas sensing applications at room temperature. The as-prepared sensor exhibited high performance when used as the sensing material for acetone detection at room temperature. Furthermore, the V₂C/V₂O₅ MXene-based sensor exhibited a higher response (S% = 11.9%) toward 15 ppm acetone than pristine multilayer V₂CT_x MXenes (S% = 4.6%). Additionally, the composite sensor demonstrated a low detection level at ppb levels (250 ppb) at room temperature, as well as high selectivity among different interfering gases, fast response-recovery time, good repeatability with minimal amplitude fluctuation, and excellent long-term stability. These improved sensing properties can be attributed to the possible formation of H-bonds in multilayer V₂C MXenes, the synergistic effect of the newly formed composite of urchin-like V₂C/V₂O₅ MXene sensor, and high charge carrier transport at the interface of V₂O₅ and V₂C MXene.

An overview of the MOF-based gas sensing materials with different electrical transduction principles.

Owing to their unique physicochemical properties, MXenes have emerged as promising materials for biosensing applications. This review paper comprehensively explores the recent advancements in MXene-based biosensors for health and environmental applications. This review begins with an introduction to MXenes and biosensors, outlining various types of biosensors including electrochemical, enzymatic, optical, and fluorescent-based systems. The synthesis methods and characteristics of MXenes are thoroughly discussed, highlighting the importance of these processes in tailoring MXenes for specific biosensing applications. Particular attention is given to the development of electrochemical MXene-based biosensors, which have shown remarkable sensitivity and selectivity in detecting various analytes. This review then delves into enzymatic MXene-based biosensors, exploring how the integration of MXenes with enzymes enhances sensor performance and expands the range of detectable biomarkers. Optical biosensors based on MXenes are examined, focusing on their mechanisms and applications in both healthcare and environmental monitoring. The potential of fluorescent-based MXene biosensors is also investigated, showcasing their utility in imaging and sensing applications. In addition, MXene-based potential wearable biosensors have been discussed along with the role of MXenes in volatile organic compound (VOC) detection for environmental applications. Finally, this paper concludes with a critical analysis of the current state of MXene-based biosensors and provides insights into future perspectives and challenges in this rapidly evolving field.