Gas nanosensors for health and safety applications in mining

High-performance plasmonics nanostructures in gas sensing: a comprehensive review

Plasmonic nanostructures have emerged as indispensable components in the construction of high-performance gas sensors, playing a pivotal role across diverse applications, including industrial safety, medical diagnostics, and environmental monitoring. This review paper critically examines seminal research that underscores the remarkable efficacy of plasmonic materials in achieving superior attributes such as heightened sensitivity, selectivity, and rapid response times in gas detection. Offering a synthesis of pivotal studies, this review aims to furnish a comprehensive discourse on the contemporary advancements within the burgeoning domain of plasmonic gas sensing. The featured investigations meticulously scrutinize various plasmonic structures and their applications in detecting gases like carbon monoxide, carbon dioxide, hydrogen and nitrogen dioxide. The discussed frameworks encompass cutting-edge approaches, spanning ideal absorbers, surface plasmon resonance sensors, and nanostructured materials, thereby elucidating the diverse strategies employed for advancing plasmonic gas sensing technologies.

Computational investigation of the perylene-TCNQ complex: effects of chalcogen and fluorine substitutions

CONTEXT

Donor-acceptor (D-A) complexes, formed between two or more molecules held together by intermolecular forces, show interesting tunable properties and found applications in diverse fields, including semiconductors, catalysis, and sensors. In this study, we investigated the D-A complexes formed between perylene and 7,7,8,8-tetracyanoquinodimethane (TCNQ) and their chalcogen (S, Se) and fluorine derivatives. It was observed that interaction energies due to complex formation increase while the HOMO-LUMO gaps decrease with chalcogen substitutions. A redshift in the electronic absorption spectra of the complexes was observed with chalcogen substitutions. The substitution of fluorine further enhanced these changes without altering the trend. These changes were found to be more for substitution with selenium compared to that of sulfur.

METHODS

The ωB97X-D/6-311+G(2df,p) level of theory was used to optimize the individual geometries, complexes, and for the frequency calculation. Atoms-in-molecule and reduced density gradient analyses were employed for the interaction study. Time-dependent density functional theory with the same level was used to analyze the electronic excitation for complexes.

Charge-Transfer Complexes: Fundamentals and Advances in Catalysis, Sensing, and Optoelectronic Applications

Supramolecular assemblies, formed through electronic charge transfer between two or more entities, represent a rich class of compounds dubbed as charge-transfer complexes (CTCs). Their distinctive formation pathway, rooted in charge-transfer processes at the interface of CTC-forming components, results in the delocalization of electronic charge along molecular stacks, rendering CTCs intrinsic molecular conductors. Since the discovery of CTCs, intensive research has explored their unique properties including magnetism, conductivity, and superconductivity. Their more recently recognized semiconducting functionality has inspired recent developments in applications requiring organic semiconductors. In this context, CTCs offer a tuneable energy gap, unique charge-transport properties, tailorable physicochemical interactions, photoresponsiveness, and the potential for scalable manufacturing. Here, an updated viewpoint on CTCs is provided, presenting them as emerging organic semiconductors. To this end, their electronic and chemical properties alongside their synthesis methods are reviewed. The unique properties of CTCs that benefit various related applications in the realms of organic optoelectronics, catalysts, and gas sensors are discussed. Insights for future developments and existing limitations are described.

Designing State-of-the-Art Gas Sensors: From Fundamentals to Applications

Gas sensors are crucial in environmental monitoring, industrial safety, and medical diagnostics. Due to the rising demand for precise and reliable gas detection, there is a rising demand for cutting-edge gas sensors that possess exceptional sensitivity, selectivity, and stability. Due to their tunable electrical properties, high-density surface-active sites, and significant surface-to-volume ratio, nanomaterials have been extensively investigated in this regard. The traditional gas sensors utilize homogeneous material for sensing where the adsorbed surface oxygen species play a vital role in their sensing activity. However, their performance for selective gas sensing is still unsatisfactory because the employed high temperature leads to the poor stability. The heterostructures nanomaterials can easily tune sensing performance and their different energy band structures, work functions, charge carrier concentration and polarity, and interfacial band alignments can be precisely designed for high-performance selective gas sensing at low temperature. In this review article, we discuss in detail the fundamentals of semiconductor gas sensing along with their mechanisms. Further, we highlight the existed challenges in semiconductor gas sensing. In addition, we review the recent advancements in semiconductor gas sensor design for applications from different perspective. Finally, the conclusion and future perspectives for improvement of the gas sensing performance are discussed.