Detection Of Gas Molecules Research Articles

Unveiling the Computational Insights into Na‐Decorated Hydrogen‐Substituted Graphdiyne for Efficient Tracing and Trapping of Nitrogen and its Oxides

Addressing air pollution is a critical concern, particularly in the context of tracing and trapping nitrogen and its oxides (N2, N2O, NO, NO2) emitted from fuel combustion. In this context, this study delves into the potential of recently discovered Hydrogen-substituted Graphdiyne (HsGDY) and to enhance its adsorption capabilities by incorporating sodium (Na) metal atom computationally. Herein, the strategic sites for Na atom decoration on HsGDY is identified and the most stable site R1 with Eads = −0.820 eV is chosen for subsequent NOx adsorption studies. Through DFT calculations, we assess the adsorptive capacity of NOx gases onto both HsGDY and Na-decorated HsGDY (NaHsGDY) slabs. In particular NO2 gas molecule with Eads = −2.537 eV emphasizes greater adsorption over NaHsGDY slab. Analysis of electronic properties reveals significant reduction in the energy gap (Eg) of the NaHsGDY, indicating heightened reactivity toward NOx gases thereby resulting in substantial increase in the slab’s conductivity. Additionally, charge density difference and Löwdin charge analyses provides consistent evidence supporting enhancement in charge transfer during NOx gases adsorption after Na decoration. The NaHsGDY slab demonstrates high selectivity, sensitivity, and superior performance than HsGDY slab, positioning it as a promising candidate for targeted NOx gas molecules detection.

Upconverting nanophosphors for various sensing applications

BackgroundUpconverting nanophosphors (UCNPs) are composed of certain nanosized inorganic host materials doped with specific rare earth ions. They exhibit the phenomenon of photon upconversion, whereby the sequential absorption of two or more low energy photons is followed by luminescent emission of multiple photons with higher energy. In addition, they have other attractive optical features such as NIR-absorption, sharp emission bands, exceptional photostability and high quantum yield. These properties make UCNPs lucrative probes for number of optical applications, such as imaging, sensing and theranostics. OverviewUCNPs have been used as specific and ultrasensitive probes for sensing of variety of analytes, such as gas molecules, metal ions, fine particles, pH and a number of molecules, biochemicals and macromolecules. Their absorption and emission in the NIR range facilitates the background free biosensing in situ, in vitro and in vivo. Their multicoloured emissions allow a suitable emission band to serve as a donor for energy transfer to another attached optical probe, while a separate emission band to serve as an internal reference in ratiometric sensing applications. This comprehensive review provides an in-depth exploration of the versatile applications of UCNPs in the optical sensing of various analytes based on energy transfer mechanisms, with emphasis on the recent developments. . The focus is on synthesizing UCNPs, surface functionalization, and their effective utilization especially in detecting gas molecules, pH changes, ions, free radicals, and disease biomarkers. Through a meticulous examination of the use of UCNPs, this review aims to contribute to a deeper understanding of their potential and pave the way for future advancements and challenges in optical sensing.

Recent Advances, Applications, and Perspectives in Erbium-Doped Fiber Combs

Optical frequency combs have emerged as a new generation of metrological tools, driving advancements in various fields such as free-space two-way time–frequency transfer, low-noise microwave source generation, and gas molecule detection. Among them, fiber combs based on erbium-doped fiber mode-locked lasers have garnered significant attention due to their numerous advantages, including low noise, high system integration, and cost-effectiveness. In this review, we discuss recent developments in erbium-doped fiber combs and analyze the advantages and disadvantages of constructing fiber combs utilizing different erbium-doped mode-locked fiber lasers. First, we provide a brief introduction to the basic principles of optical frequency combs. Then, we explore erbium-doped fiber combs implemented utilizing various mode-locking techniques, such as nonlinear polarization rotation (NPR), real saturable absorber (SA), and nonlinear amplifying loop mirror (NALM). Finally, we present an outlook on the future perspectives of erbium-doped fiber combs.

Photonic crystal gas sensors based on metal-organic frameworks and polymers.

A photonic crystal (PC) is an optical microstructure with an adjustable dielectric constant. The PC sensor was deemed a powerful tool for gas molecule detection due to its excellent sensitivity, stability, online use and tailorable optical performance. The detection signals are generated by monitoring the changes of the photonic band gap when the sensing behavior occurs. Recently, many efforts have been devoted to improving the PC sensor's detection performance and reducing technical costs by selecting and refining functional materials. In this case, metal-organic frameworks (MOFs) with a large specific surface, tunable structural properties and polymers with unique swelling properties have attracted increasingly attention. In this review, a systematic review of PC gas sensors based on MOFs and polymers was carried out for the first time. Firstly, the optical properties and gas sensing mechanism of PCs were briefly summarized. Secondly, a detailed discussion of the structural properties and rapid preparation methods of distributed Bragg reflectors (DBRs), opals and inverse opals (IOPCs) was presented. Thirdly, the recent advances in MOF, polymer and MOF/polymer-based PC sensors over the past few years were summarized. It should be noted that the sensitivity and selectivity enhancement strategy by appropriate material species selection, organic ligand functionalization, metal-ion doping, diverse functional material arrays, and multi-component compounding were analyzed in detail. Finally, prospects on PC gas sensors are given in terms of preparation methods, material functionalization and future applications.

Probing the p-type Chemiresistive Response of NiFe2 O4 Nanoparticles for Potential Utilization as Ethanol Sensor.

Detection of gas molecules and volatile organic compounds (VOCs) using efficient, low cost sensors has fetched significant attention in environmental monitoring, safety measures and medical diagnosis. In the present work, nickel ferrite (NFO) nanoparticles are explored as p-type semiconducting metal oxide (SMO) sensor for detection of five different organic vapors namely methanol, ethanol, n-propanol, iso-propanol and acetone which often cause severe damage to human body under prolonged exposure. The sensing studies in presence of the aforementioned five vapors are carried out by varying the sensor operating temperature (225-300 °C) and vapor concentrations (10-1000 ppm). Developed NFO sensor demonstrated best performance in terms of sensing (~10 ppm), response time (<10 s), excellent repeatability and selectivity towards ethanol among all other considered gas species. The repeatability of the sensor response is verified and the underlying reasons for the variation in the response of NFO sensor due to the change of operating temperature, analyte type and concentrations has been discussed. The synthesis of NFO through auto combustion method and study on their formation behaviour, oxygen vacancy evolution, band gap calculation, crystalline nature as well as microstructural features provides here the comprehensive information about the potential application of NFO nanoparticles as gas sensor.

Quantitatively sensitive and resolution-enhancing strategies in optical signal conversion of SPR images using extensive angle-scanning and image-reconstruction

Surface plasmon resonance imaging (SPRi) is a technology developed from SPR that has emerged in response to the growing need for high-throughput and for discovering diverse applications across multiple domains. Despite its potential, SPRi has encountered limitations in sensitivity when handling low-molecular-mass materials, which emphasizes the need for the quantitative processing of SPRi signals. In this study, an SPRi signal conversion process was developed to enhance the contrast of SPR images and convert them into quantitatively analyzed signals. At first, an optimum incident angle of light was determined as an angle that maximized the difference between sums of the brightness % of functionalized regions and the brightness % of background region in the SPR image, which enabled to obtain a distinct SPR image. In addition, the enhancement of contrast and reduction of noise in the SPR image was achieved using Contrast Limited Adaptive Histogram Equalization (CLAHE) method. Then various pixel domains of the SPR images were simultaneously quantified and visualized the multi-pixel processing technique. For validating the process, an SiO2/Au thin film was modified with four different functionalities and applied to the detection of gas molecules. The SPR images processed using the proposed process exhibited sensitive and quantitative information about the interactions of the functionalities with the target gas in the distinct multiple regions, thus, were applicable to the quantitative monitoring of various phenomena occurring on the plasmonic interface via the advantages of SPRi.

Brillouin lasers in a graphene microresonator for multispecies and individual gas molecule detection

Optical microcavities offer a promising platform for highly efficient light–matter interactions. Recently, the combination of microresonators and 2D materials in nanoscale has further enriched the optoelectronics of the microcavity geometries, spurring broad advances ranging from lasers, nonlinear converters, modulators to sensors. Here, we report the concept of a Brillouin laser sensor, by depositing graphene on an over-modal microsphere. Driven by a single continuous-wave pump at 1550 nm, multiple Brillouin lasers from distinct mode families are co-generated in a single device. The Brillouin lasers excited in the high Q cavity produce heterodyne beating notes with phase noise down to −161 dBc/Hz at 1 MHz offset, not only enabling label-freely identifiable detection of multispecies gas molecules adsorbed on the graphene in situ but also rendering it possible to trace individual molecules. Such a combination of graphene optoelectronics and Brillouin lasers in microcavities demonstrates a novel physical paradigm and offers insights into powerful tools for fast and precise optical sensing.

GAS SENSOR BASED ON THE SPECTRAL SPR EFFECT WITH COLORIMETRIC REGISTRATION OF RESPONSES

A new variant of the optoelectronic sensor for the detection of gas molecules based on the effect of spectral surface plasmon resonance (SPR) in the chromatic mode with colorimetric registration of the color components of the reflected light is proposed. As an optical sensitive element, a thin silver film was used on the base face of the prism in the Kretschmann geometry, which made it possible to realize a full-fledged SPR effect in the entire visible spectral range from 450 to 700 nm. To measure the optical response, the method of video registration of R, G, B components of reflected light by color webcam was used. The optical scheme of the set-up allowed to simultaneously obtain the full spectrum of plasmon-reflected light without the use of rotating mechanical parts. The sensory effect was a change in the refractive index of the surrounding medium under the action of gases, which directly affected the parameters of the spectral SPR. A laboratory prototype of an optoelectronic sensor device was created, and the effectiveness of the proposed method was evaluated by detection of a number of organic analytes vapors .

SPR chromatic sensor with colorimetric registration for detection of gas molecules

In this work, we have proposed and tested a new version of an optoelectronic sensor for detecting gas molecules based on the effect of spectral surface plasmon resonance (SPR) in the chromatic mode with colorimetric registration of the R, G, B color components of reflected light. A thin 40-nm silver film on the base face of the prism with SPR excitation in the Kretschmann geometry is used as an optical sensitive element that allows us to realize a full-fledged SPR effect in the entire visible range of the spectrum from 450 to 700 nm. The physical nature of the sensory effect is a change in the refractive index of the sensitive coating on the silver film, which directly affects the SPR parameters. The films of polyvinyl formal ethylal were used as a coating selective to the number of organic analytes. A laboratory version of the portable device for implementation of a gas sensor based on the SPR-RGB effect was created. Performance of the proposed sensory method and the corresponding device were assessed using different types of alcohols as volatile organic analytes.

Triboelectric-induced ion mobility for artificial intelligence-enhanced mid-infrared gas spectroscopy

Isopropyl alcohol molecules, as a biomarker for anti-virus diagnosis, play a significant role in the area of environmental safety and healthcare relating volatile organic compounds. However, conventional gas molecule detection exhibits dramatic drawbacks, like the strict working conditions of ion mobility methodology and weak light-matter interaction of mid-infrared spectroscopy, yielding limited response of targeted molecules. We propose a synergistic methodology of artificial intelligence-enhanced ion mobility and mid-infrared spectroscopy, leveraging the complementary features from the sensing signal in different dimensions to reach superior accuracy for isopropyl alcohol identification. We pull in “cold” plasma discharge from triboelectric generator which improves the mid-infrared spectroscopic response of isopropyl alcohol with good regression prediction. Moreover, this synergistic methodology achieves ~99.08% accuracy for a precise gas concentration prediction, even with interferences of different carbon-based gases. The synergistic methodology of artificial intelligence-enhanced system creates mechanism of accurate gas sensing for mixture and regression prediction in healthcare.

Simulation of NOx and COx Gas Sensor based on Pristine Armchair Stanene Nanoribbon

AbstractIn this study, the adsorption of the most common hazardous gases (CO, NO, NO2, and CO2) on the stanene armchair nanoribbon of width 6 (H‐ASnNR(6)) is investigated using density functional theory. The most stable adsorption sites, adsorption energies, charge transfer, electronic features, transmission spectra, and current–voltage analysis are explored. All molecules are physisorbed on H‐ASnNR(6) through van der Waals interactions, indicating a potential use for this material in recoverable gas sensors, and all gas molecules act as acceptors. Additionally, the highest and the lowest charge transfer is related to the NO and CO2 molecules, respectively. It is revealed that the adsorption of NO and NO2 affects the electronic properties of the H‐ASnNR(6), and the system displays conducting behavior, while the influence of CO and CO2 gas molecules on the electrical properties of H‐ASnNR(6) is relatively small. The results demonstrate that compared to pristine H‐ASnNR(6), the transmission function of the gas plus H‐ASnNR(6) system undergoes a significant change, particularly after the adsorption of NO and NO2 molecules. The presence and absence of the molecules are shown by current–voltage (I–V) characteristic results. The results suggest that H‐ASnNR(6) has the potential to be used in gas molecule detection applications.

Improved NO2 gas sensing performance of nanoporous conjugated polymer (CP) thin films by incorporating preformed CP nanowires

Conjugated polymer (CP)-based organic field-effect transistor (OFET) gas sensors can detect gas molecules at room temperature with high sensitivity and selectivity. However, their performance, particularly when detecting oxidizing gases, has fallen behind that of their metal oxide counterparts. Hence, improving their sensing performance as well as understanding the correlation between it and the structural and electrical properties of the sensing materials is necessary. Herein, we demonstrate that gas sensing performance of an OFET sensor based on nanoporous poly(3-hexylthiophene) (P3HT) films can be improved simply by incorporating preformed P3HT nanowires (NWs), which act as an efficient charge transport pathway. It detects nitrogen dioxide (NO2) molecules with high sensitivity due to the efficient charge transport pathway as well as ultrathin nanoporous structure of the P3HT films. Upon exposure to 10 ppm NO2 at room temperature, the OFET gas sensor based on the P3HT-NW embedded nanoporous P3HT film exhibits excellent responsivity (34%), fast response and recovery times (∼69 and ∼133 s, respectively), and a low limit of detection of under 0.1 ppm, which are comparable to those of conventional metal oxide-based gas sensors. Based on the correlation study between the morphology, charge transport ability, and sensing performance of the P3HT-NWs embedded nanoporous P3HT films, it is revealed that the efficient charge transport ability is an important factor for realizing high-performance CP-based OFET gas sensors, along with excellent morphological features such as thinness and high pore density.

Design and Simulation of a Ratiometric SPR Sensor Based on a 2D van der Waals Heterojunction for Refractive Index Measurement.

Surface plasmon resonance (SPR) sensors have been widely applied in many fields because of their advantages of working in real time and high sensitivity. However, because the spectrum of an SPR sensor is easily affected by the smoothness of the metal surface, this type of sensor has obvious disadvantages in the application of quantitative detection. We designed an SPR refractive index sensor for molecular detection that has the advantage of quantifiability. A ratio spectral quantitative analysis method was established based on the two coherent dips of the SPR spectrum formed by the strong coupling effect between the surface plasmon polaritons and the excitons of the J-aggregate molecule 5,6-dichloro-2-[3-[5,6-dichloro-1-ethyl-3-(4-sulfobutyl)-2-benzimidazoline subunit] propenyl]-3-ethyl-1-(4-sulfobutyl) benzimidazole hydroxide inner salt (TDBC). The introduced MoS2/graphene van der Waals heterojunction produced an effective charge transfer to the Ag film, resulting in significant electric field enhancement at the sensing interface and further improving the detection sensitivity of the sensor. The simulation results showed that for 43 nm Ag film, for example, the ratiometric SPR sensor with the Ag film structure can obtain 16.12 RIU-1 sensing sensitivity, applied to the detection of gas molecules, while the SPR sensor with single-layer graphene and three layers of MoS2 heterostructures can obtain 50.68 RIU-1 sensing sensitivity. The addition of van der Waals heterostructures can significantly improve sensing performance by 215%.

High-Performance Nitric Oxide Gas Sensors Based on an Ultrathin Nanoporous Poly(3-hexylthiophene) Film.

Conjugated polymer (CP)-based organic field-effect transistors (OFETs) have been considered a potential sensor platform for detecting gas molecules because they can amplify sensing signals by controlling the gate voltage. However, these sensors exhibit significantly poorer oxidizing gas sensing performance than their inorganic counterparts. This paper presents a high-performance nitric oxide (NO) OFET sensor consisting of a poly(3-hexylthiophene) (P3HT) film with an ultrathin nanoporous structure. The ultrathin nonporous structure of the P3HT film was created via deposition through the shear-coating-assisted phase separation of polymer blends and selective solvent etching. The ultrathin nonporous structure of the P3HT film enhanced NO gas diffusion, adsorption, and desorption, resulting in the ultrathin nanoporous P3HT-film-based OFET gas sensor exhibiting significantly better sensing performance than pristine P3HT-film-based OFET sensors. Additionally, upon exposure to 10 ppm NO at room temperature, the nanoporous P3HT-film-based OFET gas sensor exhibited significantly better sensing performance (i.e., responsivity ≈ 42%, sensitivity ≈ 4.7% ppm-1, limit of detection ≈ 0.5 ppm, and response/recovery times ≈ 6.6/8.0 min) than the pristine P3HT-film-based OFET sensors.

Controlled growth and fabrication of edge enriched SnS2 nanostructures for room temperature NO2 gas sensor applications

Nanostructured SnS2 with enhanced edge sites was prepared and investigated the impact on NO2 gas molecules detection at room temperature (RT). SnS2 flower-like structure with exposed active sites provides more interaction channels for the NO2 gas molecules. The crystal orientation along with the (011) plane exhibits more active edge sites, thus enhancing the sensing performance of the flower-like structure. The fabricated SnS2 gas sensor showed more selective towards NO2 gas molecules. SnS2 flower-like structure provides more stability of 81.22% and 32.63% increased sensing response compared to the platelet-like structure. This result provides a pathway for the development of a practical room temperature NO2 gas sensor.

Novel Design of 0D Nanoparticles-2D Transition-Metal Dichalcogenides Heterostructured Devices for High-Performance Optical and Gas-Sensing Applications

Two-dimensional Transition metal dichalcogenides (TMDCs), have now attracted much attention due to their unique layered structure and physical properties. Up to date, several studies have demonstrated monolayered and few-layered TMDC-based photodetectors with good stability, photo-switching time and broadband detectivity from UV to infrared light region. However, the reported responsivity is not as high as the theoretical expectation, indicating that the light absorption is limited by the atomic thickness of 2D-TMDCs and could still be improved. To overcome the drawback of low absorption in 2D TMDC materials, previous reports have revealed several strategies to enhance the electric field and light-harvesting in these atomically thin TMDC layers by hybridizing plasmonic noble-metal nanoparticles, such as Pt, Au and Ag, to facilitate the light-matter interaction at the surface of semiconductors. In this regard, we aim to combine highly absorptive CuInS2(CIS) nanocrystals with noble metal nanoparticles as the photosensitizer to enhance the intrinsic absorptivity and promote the performance of MoS2-based photodetectors. The interests of noble nanocrystals such as platinum and gold are featured for their distinctive properties of the carrier transportation and the storage when combined with semiconductor materials. The strategy described here acts as a perspective to significantly improve the performance of MoS2-based photodetectors with outstanding detection responsivity with selectable wavelengths by further controlling the size and material of the decorated CIS nanocrystals.In addition to optical sensing, TMDCs have also been developed as a promising candidate for gas-molecule detection. Different from commercial metal oxide gas sensors, TMDCs as sensing materials can be operated at room temperature with good performance, increasing its reliability for future industrial applications. Nevertheless, the relatively low response and long response/recovery time are the main drawbacks of these promising devices. Therefore, we proposed the approach to successfully increase the surface area of TMDCs by a one-step synthesis from WO3 into three-dimensional (3D) WS2 nanowalls through a rapid heating and rapid cooling process. Moreover, the combination of CdS/ZnS or CdSe/ZnS core/shell quantum dots (QDs) with different emission wavelengths and WS2 nanowalls will further improve the performance of WS2-based photodetector devices, including 3.5~4.7 times photocurrent enhancement and shorter response time. The remarkable results of the QD-WS2 hybrid devices to the high non-radiative energy transfer (NRET) efficiency between QDs and our nanostructured material are caused by the spectral overlap between the emission of QDs as the donors and the absorption of WS2 as the acceptors. Additionally, the outstanding NO2 gas-sensing properties of QDs/WS2 devices were demonstrated with a remarkably low detection limit down to 50 ppb with a fast response time of 26.8 s, contributed by tremendous local p-n junctions generated from p-type WS2 nanowalls and n-type CdSe-ZnS QDs in this hybrid system.Our strategies to combine 0D nanoparticles or quantum dots and 2D TMDC materials can significantly enhance the optical sensing and gas molecule sensing properties compared to pristine TMDC-based devices, resulting from the efficient charge or energy transfer between the multi-dimension material system and the creation of local p-n junctions. Moreover, the scalability of these hybrid nanostructures allows our devices to exhibit much more possibilities in advanced multifunctional applications.

A DFT study of gas molecules adsorption on intrinsic and Cu-doped graphene gas nanosensors

In this study, first-principles calculations are performed to investigate the sensitivity of intrinsic graphene sheet (GS) and Cu-doped graphene sheet (Cu-GS) gas nanosensors for adsorbing CO, H2, and H2S gas molecules using QUANTUM ESPRESSO package. The density of states (DOS), net charge transfer, adsorption energy, partial density of states (PDOS), and the most stable adsorption configuration of these molecules on GS and Cu-GS are studied. The results show the weak physical adsorption of the three gas molecules on GS. The strength of interaction between the Cu-GS system and adsorbed gas molecules is higher due to the Cu doping. It is expected that the significant increase in charge transfer and adsorption energy leads to fundamental improvement in the electrical conductivity of the Cu-GS system. The results indicate that the introduction of Cu impurity can improve the gas sensing properties of graphene-based gas nanosensors. Therefore, Cu-GS is more appropriate for detecting gas molecules compared to pure GS. The results in this study are useful for developing the design of gas nanosensors.

A first-principles study of gas molecule adsorption on two-dimensional borophene

The effect of two-dimensional borophene on the adsorption properties of gas molecules was studied by first-principles method. The adsorption energies of gas molecule on the four adsorbed site were first computed. Through compare these adsorption energies of different adsorbed site, the most stable of adsorption configuration were determined. In order to confirm the interaction mechanism of gas molecule and borophene, the charge population of borophene-gas molecule were computed. The calculated shows that the CO, NO and NO2 molecule are adsorbed on the borophene nanosheet with chemical adsorption. The further charge population analysis of the borophene-CO and the borophene-NO adsorption system shows that the electrons transfer from borophene nanosheet to CO and NO molecule. It is can be seen that the borophene acts as electron donor and gas molecule acts as electron acceptor. Based on the above the calculation and analysis, we concluded that the borophene materials is an excellent candidates to detect gas molecules.

Adsorption of Gas Molecules on HfSSe Janus Monolayer

The density functional theory (DFT) method have already been used to study the electronic, optical and the adsorption properties of (CO, CO2, NO, NO2, SO2) gas molecules on HfSSe (Se and S) monolayer. Initially, the properties of pristine HfSSe monolayer are calculated. The band gap of HfSSe (Se and S) monolayer is estimated to be 0.626eV which authorize the semiconducting behavior. The results show that the adsorption of gases occurs at different sites on the studied monolayer. However, every the adsorption energies are negatives and the adsorption of gas molecules on this monolayer undergoes physisorption interaction, thus they can be used to detecting gas molecules. The refractive indices of HfSSe-S monolayer are larger than that in HfSSe-Se monolayer, and reach to 2.50 and 2.31 of CO2 and SO2gases, approximately. On the opposite, the reflection peaks of the monolayer occur in the UV region range which agrees with the absorption coefficient. Besides, the maximum value of reflectivity in the adsorbed systems does not exceed 60%.

Temperature dependence of adsorption and desorption dynamics of NO2 molecule on boron-doped graphene

Two-dimensional materials have promised an important application as gas sensors due to their big surface areas. Although it's conceptually attractive, the real performance may be dramatically altered at finite temperatures. Therefore, to find out the underlying physical mechanism or dynamics at finite temperatures is of importance before any actual application. Here, we find that boron-doped graphene (BG) should be an ideal sensor to detect gas molecules such as NO2. Our results from first-principle molecular dynamics simulations show NO2 molecule can adsorb stably on BG at room temperature. Furthermore, its desorption time from BG is in the level of micro-seconds (ms), which has fully met the standards of industrial applications. The desorption time will be further decreased to the pico-seconds (ps) level at higher temperature, promising an opportunity for BG to detect the NO2 molecule using more accurate and sensitive measuring techniques, for example femtoseconds laser or terahertz pulses.