High Selectivity For H2S Research Articles

Mild oxidizing synthesis of non-agglomerated Fe2O3 nanoparticles for H2S gas sensing

Agglomeration is the most common phenomenon in synthesizing nanopowders, which strictly reduces the quality of the products. In the present study, a non-agglomerated iron oxide nanopowder was synthesized via direct oxidation method from metallic iron by hydrogen peroxide. The H2S gas sensing of the nanoparticles was also investigated. The products were evaluated via XRD, TEM, XPS and BET techniques. The results showed that a precisely size-controlled iron oxide with an average particle size of 12 nm was obtained. XRD results confirmed the amorphous nature of the particles. The produced nanoparticles had a high surface area of about 92 m2/g. The powders were dispersed in water for more than three months without sedimentation. XPS results showed the existence of Fe3+ in the samples which confirms the formation of the Fe2O3 phase. The finding showed that the produced samples exhibited a high H2S detection ability. The detection limit was about 100 ppb, and the greatest sensitivity was attained at 100 ppm concentration of H2S. Additionally, the sensor's behavior in the presence of other gases shows that it has high H2S selectivity. This synthesis method introduces a new approach for producing non-agglomerated oxide ceramics with nanoscale via a mild oxidizing media from metal powders.

High-Sensitivity Hydrogen Sulfide Electrochemical Gas Sensor Based on CNT/Pt Cluster Electrode

Recently, due to the development of industrial technology, harmful gases discharged from industrial sites are gradually increasing, and as a result, inconvenience and civil complaints due to odor in the community are rapidly increasing. Among several types of harmful gases, hydrogen sulfide (H2S) is a colorless representative harmful gas that can cause pain through irritation of the mucous membranes of the eyes and respiratory tract, and can cause central nerve paralysis and suffocation at the same time when exposed to high concentrations. In addition, H2S is not only harmful to the human body, but also can create an unpleasant feeling by causing an odor even in a very small amount. Therefore, in order to manage H2S, research on a gas sensor capable of quickly and stably detecting H2S has been actively conducted. Most of the sensors that have been studied in the past are metal oxide-based semiconductor H2S gas sensors, which have high sensitivity, but have disadvantages in that low selectivity and high-temperature operating conditions are required. On the other hand, the electrochemical gas sensor can measure H2S gas with high selectivity because a chemical reaction occurs with respect to a specific gas depending on the type of electrolyte and electrode, and a potential difference due to electrons generated thereby is measured. Therefore, in this study, a CNT/Pt-based electrochemical H2S gas sensor capable of detecting at room temperature with high selectivity for H2S was developed. After forming a CNT thin film on a PTFE membrane, Pt was deposited through an E-beam to fabricate a working electrode capable of selectively detecting only H2S, and applied to an electrochemical H2S gas sensor using sulfuric acid (H2SO4) electrolyte. H2S was measured at a concentration of 100 to 10 ppm in units of 10 ppm using the manufactured CNT/Pt-based electrochemical H2S gas sensor. As a result, the amount of current change was confirmed to be 100uA at a concentration of 100 ppm, and the response time and recovery time were confirmed to be about 10 seconds.This work was supported by the Korea Innovation Foundation(INNOPOLIS) grant funded by the Korea government(MSIT) (2020-DD-UP-0348). This study has been conducted with the support of the Korea Institute of Industrial Technology as "Development of a thermal convection-type flow sensor with high-sensitivity for emergency patients breathing monitoring in real-time" (Kitech UI-23-0012).

H2S-sensing properties of flame-synthesized RuO2-decorated WO3 nanoparticulate spin-coated films

This work aimed to develop effective and reliable H2S gas sensors based on flame-synthesized RuO2-decorated WO3 spin-coated films. Inclusive material characterizations unveiled the decoration of 1–3 nm RuO2 nanoparticles on 10–25 nm WO3 nanoparticles with 0–1 wt% Ru. Sensing layers coated with 1–6 cycles were tested towards 0.25–10 ppm H2S at 200–400 °C under various humidity conditions (0–80 %RH). The sensors with four spin-coated layers and 0.2 wt% Ru presented a reproducibly optimum response of ∼71.0 with a fair response time of ∼ 15.1 s to 10 ppm H2S in dry ambient at 350 °C. Additionally, the optimal sensor exhibited high H2S selectivity with respect to CH3SH, CH3SCH3, C3H6O, C2H5OH, CH3OH, CH2O, C6H6, C8H10, NO2, NO, H2, CH4, CO2, C2H2, HCOOH, CH3COOH, and CH3CHOHCOOH. Furthermore, the sensors displayed decent repeatability and satisfactory medium-term stability of resistance and response. Therefore, flame-synthesized RuO2-loaded WO3 nanoparticles were promising for effective and practical H2S sensing.

Enhanced H2S Gas-Sensing Performance of Ni-Doped ZnO Nanowire Arrays.

Ni-doped ZnO nanowire arrays (Ni-ZnO NRs) with different Ni concentrations are grown on etched fluorine-doped tin oxide electrodes by the hydrothermal method. The Ni-ZnO NRs with a nickel precursor concentration of 0-12 at. % are adjusted to improve the selectivity and response of the devices. The NRs' morphology and microstructure are investigated by scanning electron microscopy and high-resolution transmission electron microscopy. The sensitive property of the Ni-ZnO NRs is measured. It is found that the Ni-ZnO NRs with an 8 at. % Ni precursor concentration have high selectivity for H2S and a large response of 68.9 at 250 °C compared to other gases including ethanol, acetone, toluene, and nitrogen dioxide. Their response/recovery time is 75/54 s. The sensing mechanism is discussed in terms of doping concentration, optimum operating temperature, gas type, and gas concentration. The enhanced performance is related to the regularity degree of the array and the doped Ni3+ and Ni2+ ions, which increases the active sites for oxygen and target gas adsorption on the surface.

Gold Nanoparticles Decorated Copper Oxide Nanosheets Sensor for Hydrogen Sulfide Gas Sensing at Room Temperature

This study exhibits a highly H2S-selective gas sensor based on copper oxide nanosheets (CuO-NSs) material. CuO-NSs are fabricated by a simple and economical method. CuO-NSs are decorated by gold nanoparticles (AuNPs) and used to detect H2S at room temperature. The AuNPs decorated CuO sensor has responses of 36.55% to 69.67% at 0.1 to 0.5 ppm of H2S while the pure sensor has responses from 4.77% to 13.37%. It can be seen that AuNPs can enhance H2S sensing responses five to nine times higher than pure one. The sensor also shows high H2S selectivity against NH3, SO2 and volatile organic compounds (VOCs). The beneficial effect of AuNPs allow the H2S detection of CuO material down to ppb and even lower level, which make it possible to be applied in environmental applications and portable devices.

Thermal shock-stabilized metal catalysts on oxide hemitubes: Toward ultrasensitive chemiresistors

To achieve powerful gas sensors oxide semiconductor chemiresistors, the uniform functionalization of nanocatalysts on the desired metal oxides is considered as a key strategy. However, still, it is challenging to achieve the nanocatalysts decoration on desired oxides without deterioration of target materials. In this study, thermal-shock (rapid joule-heating method) was applied to uniformly decorate Pt nanoparticles (NPs) on the surface of carbon nanofibers (CNFs) to achieve the uniform distribution of Pt NPs on one-dimensional structures. And then, SnO2 was physically deposited on the Pt NPs loaded CNFs and continuous heat-treatment was conducted to transfer the Pt NPs to desired SnO2 porous hemitubes. Thanks to the well-distributed Pt NPs on porous SnO2 hollow structures, the Pt laoded SnO2 hemitubes showed an exceptional sensitivity (Rair/Rgas = 1500 at 5 ppm) in H2S. Also, it showed high selectivity for H2S and high stability even under continuous gas exposure, confirming its potential as an effective H2S sensor.

A dicyanoisophorone-based near-infrared fluorescent probe with fast detection for H2S in living cells and zebrafish

Hydrogen sulfide (H2S) is a well known gaseous signal transmitter in physiological and pathological processes. Herein, we developed a near infrared (NIR) fluorescence probe XXMU-H2S based on dicyanophosphone derivatives, which was surprisingly found to show high selectivity for H2S over various other analytes including biothiols, making it feasible to detect H2S in living system. After reaction with H2S, this probe showed rapid and significant turn-on NIR emission changes centered at 686 nm within 10 min, a remarkable large Stokes shift (138 nm) and high sensitivity (LOD: 16 nM). Furthermore, the probe has also been successfully applied to imaging of exogenous and endogenous H2S in living cells and zebrafish.

Rapid and sensitive detection of H2S by a 4-phenylselenium coumarin as a dual-active-site fluorescent probe

Hydrogen sulfide (H2S) is associated with numerous psychological and pathological processes, and related closely with human health and diseases. The detection of H2S is a key to better understand its roles. In this paper, we developed a 4-phenylselenium coumarin (PhSeCou) as a rapid-response fluorescent probe for the selective and sensitive detection of H2S. The probe PhSeCou is a stable and almost non-fluorescent molecule in a PBS buffer, and it can rapidly (< 60 s) sense H2S to give a strongly fluorescent product, Cou-H2S (Φf = 0.11, centered at 563 nm), thereby achieving to a sensitive detection at an ultra-low limit of detection (8.8 nM). The fluorescent probe displays a high selectivity for H2S over biothiols and other relevant analytes. What is more, through fluorescence cell-imaging, PhSeCou was successfully applied to detect exo- and endogenous H2S in living cells.

Trace Hydrogen Sulfide Sensing Inspired by Polyoxometalate-Mediated Aerobic Oxidation.

A high-performance chemiresistive gas sensor is described for the detection of hydrogen sulfide (H2S), an acutely toxic and corrosive gas. The chemiresistor operates at room temperature with low power requirements potentially suitable for wearable sensors or for rapid in-field detection of H2S in settings such as pipelines and wastewater treatment plants. Specifically, we report chemiresistors based on single-walled carbon nanotubes (SWCNTs) containing highly oxidizing platinum-polyoxometalate (Pt-POM) selectors. We show that by tuning the vanadium content and thereby the oxidation reactivity of the constituent POMs, an efficient chemiresistive sensor is obtained that is proposed to operate by modulating CNT doping during aerobic H2S oxidation. The sensor shows exceptional sensitivity to trace H2S in air with a ppb-level detection limit, multimonth stability under ambient conditions, and high selectivity for H2S over a wide range of interferants, including thiols, thioethers, and thiophene. Finally, we demonstrate that the robust sensing material can be used to fabricate flexible devices by covalently immobilizing the SWCNT-P4VP network onto a polyimide substrate, further extending the potentially broad utility of the chemiresistors. The strategy presented herein highlights the applicability of concepts in molecular aerobic oxidation catalysis to the development of low-cost analyte detection technologies.

Flame spray pyrolysis synthesis and H2S sensing properties of CuO-doped SnO2 nanoparticles

In this work, CuO-doped SnO2 (CuO/SnO2) nanoparticles with different CuO mass fractions (0–1.0 wt%) are synthesized by a flame spray pyrolysis (FSP) route and applied to fabricate thin-film gas sensors for H2S detecting. The nanoparticles are characterized by X-ray diffraction (XRD), N2-physisorption isotherms, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Within the 0–1.0 wt% CuO-doping concentrations, all of the nanoparticles predominantly exhibit a spherical structure with a diameter of 5–15 nm, and possess a quite large specific surface area (110–125 m2/g). These textural characterizations suggest that Cu atoms form substitution doping in polycrystalline SnO2 nanoparticles at low CuO levels (< 0.5 wt%), and they are segregated as CuO nanoclusters at high CuO concentrations (0.5–1.0 wt%). From gas-sensing measurements, the CuO doping significantly improves the H2S sensing performance of SnO2 nanoparticles, especially at the optimal CuO-doping mass fraction of 0.5 wt%. The optimal CuO-doped SnO2 gas sensor exhibits a highest response (Ra/Rg = 1056) under a condition of 10 ppm H2S atmosphere at 125 °C. This is probably because a large number of highly dispersed small CuO nanoclusters are supported on the surface of the nanoparticle for 0.5 wt% doping, forming abundant p-n junctions with SnO2. When the CuO/SnO2 composite is exposed to H2S, semiconducting CuO is converted to metallic-like CuS, thereby increasing electrical conductivity and resulting in a high response. In addition, the optimal sensor displays good cycle performance and high H2S selectivity against other toxic and flammable gases including NH3, H2 and CO. Therefore, the gas sensor of 0.5 wt% CuO-doped SnO2 made by the FSP shows a large potential for H2S detecting in practical industrial application.

A turn-on fluorescence probe for hydrogen sulfide in absolute aqueous solution.

A turn-on hydrogen sulfide (H2S) fluorescence probe, 4-{2-[4-(2,4-dinitrophenoxy)-phenyl]-vinyl}-1-methyl-pyridinium iodide (DPPVP), based on the thiolysis reaction of dinitrophenyl ethers (DNP) has been proposed. Pyridinium structure enhanced the water solubility of DPPVP, which could quickly respond to H2S in absolute PBS solution and the fluorescence spectra of DPPVP at 520 nm were turned on by H2S. The spectra results exhibited that DPPVP could sensitively detect H2S with satisfied linear range (0-40 μM) and detection limit (13.4 nM). The high selectivity for H2S against biothiols was attributed to the significant difference in the pKa and the molecular size. Moreover, DPPVP has been successfully used for detecting H2S in vegetable.

Nitrobenzoxadiazole Ether-Based Near-Infrared Fluorescent Probe with Unexpected High Selectivity for H2S Imaging in Living Cells and Mice

H2S is an important endogenous gasotransmitter, and its detection in living systems is of great significance. Especially, selective and sensitive near-infrared (NIR) fluorescent H2S probes with rapid response and large Stokes shift are highly desirable because of their superiority for in vivo detection. Probes with nitrobenzoxadiazole (NBD) ether as reaction sites have been well-explored recently to detect biothiols or H2S/biothiols simultaneously, rather than to detect H2S selectively. In this work, a new NBD ether-based NIR fluorescent probe was developed, which was unexpectedly found to show high selectivity for H2S over various other analytes including biothiols, making it practical for specific detection of H2S both in vitro and in vivo. Upon response to H2S, this probe showed rapid and significant turn-on NIR emission changes centered at 744 nm within 3 min, together with a remarkable large Stokes shift (166 nm) and high sensitivity (LOD: 26 nM). Moreover, imaging exogenous and endogenous H2S in living cells and rapid imaging of H2S in living mice with this probe was successfully applied with excellent performance.

Selective imaging of analytes in living cells and zebrafish using a novel peptide-based fluorescence chemosensor with different responses

Monitoring and imaging the requirements of heavy metal ions in organisms are very strict, so biologists and chemists wishfully expect powerful probes to achieve. Herein, DnsP has been successfully designed and synthesized using a highly biocompatible and low biotoxic peptide backbone as an ionophore to selectively detect Zn2+ and Cu2+ in aqueous solution in different response modes. In addition, the DnsP-Cu2+ system has high selectivity for H2S and can restore the fluorescence of DnsP for the detection of S2−. Finally, DnsP demonstrated excellent cell permeation and low biological toxicity for biosensing in cellular and zebrafish. Therefore, DnsP represents a prominent peptide fluorescence chemosensor, capable of multifunctional analyte detection and continuous response imaging in environmental and biological systems.

BODIPY-based naked-eye fluorescent on-off probe with high selectivity for H2S based on thiolysis of dinitrophenyl ether

1-(2-Hydroxyphenyl)ethanone as a starting material, BODIPY 3 bearing 2,4-dinitrophenyl (DNP) group was prepared in total 7% yield. Probe 3 was strongly fluorescent. Sulfhydryl-specific cleavage reaction released the hydroxyl group. Due to the electron transfer of the hydroxyl group in 2 to the BODIPY core, dye 2 was weakly fluorescent. Naked-eye and fluorescent turn-off probe 3 was highly selective and sensitive to H2S, and could be used to detect HS− in HCT-116 and CT-26 cells, indicating its potential application for studying the effect of HS− in biological system.

Enhanced response and selectivity of H2S sensing through controlled Ni doping into ZnO nanorods by using single metal organic precursors

We report on enhancing the selectivity and response of room (23 °C) and high temperature H2S gas sensing through controlled Ni doping (0–10 at%) into ZnO nanorods (NRs) grown with a facile solution growth method using a single hybrid bimetallic metal-organic precursor (nickel/zinc acetylacetonate). The morphology, microstructure, surface chemistry and photoluminescence properties of the as-grown NRs are extensively examined. The gas sensing results are discussed in terms of doping concentration, operating temperature, gas type, gas concentrations and relative humidity. The optimal response toward 100 ppm of H2S reaches 3.1 at 23 °C and increases to 45.3 at 200 °C for 8 at% Ni-doped ZnO NR sensors, where the corresponding response/recovery time at 23 °C and 200 °C also reaches 76/160 and 48/60 s, respectively. The same sensor exhibits high H2S selectivity over other gases, including CH4, CH3OH and C2H5OH. The enhancement of gas sensing is attributed to increasing the number of active sites for adsorption of oxygen and target gases on the surface through incorporation of Ni3+ over Ni2+ ions. At 23 °C, the sensing mechanism is related to the formation of a 7 nm-thick ZnS layer over the NRs through reactions between H2S and adsorbed oxygen.

H2S sensing characteristics of Ni-doped CaCu3Ti4O12 films synthesized by a sol-gel method

The problem of detecting the toxic hydrogen sulfide (H2S) gas at part per million levels in air by means of simple solid state gas sensors is relevant to environmental and gas processing industries. In this work, high-performance H2S gas sensors are developed based on nickel-doped calcium copper titanate (Ni-doped CCTO) thin films synthesized by a sol-gel method. From gas-sensing measurements, the response of Ni-doped CCTO sensing films increased substantially with increasing Ni doping level from 1.5 to 7.3 wt%, revealing a catalytic effect of Ni on the surface reactions with adsorbed H2S molecules. In particular, 7.3 wt% Ni-doped CCTO sensors offered a high response of 120 for 10 ppm of H2S at the optimal operating temperature of 250 °C, an order of magnitude higher than that of undoped one. In addition, the response time dropped significantly from ∼80 s to ∼4 s while the recovery time slightly improved as the Ni doping content increased from 0 to 7.3 wt%. Moreover, the Ni-doped CCTO sensors exhibited good reproducibility and high H2S selectivity against ethanol, H2, NO2 and NH3. Therefore, the Ni-doped CCTO sensors are highly promising for sensitive and selective detections of H2S.

Highly-sensitive H2S sensors based on flame-made V-substituted SnO2 sensing films

In the present work, 0–2wt% vanadium (V)-doped SnO2 nanoparticles synthesized by flame spray pyrolysis were systematically studied for H2S detection. The sensing films (∼15–20μm in thickness) were homogeneously prepared by spin coating technique on Au/Al2O3 substrates. Structural characterizations by electron microscopy and X-ray analysis confirmed the formation of agglomerated SnO2 nanoparticles (5–20nm) with highly crystalline tetragonal-cassiterite SnO2 structure and V substitutional doping with mainly V5+ oxidation state. The gas-sensing studies revealed that the H2S response of flame-made SnO2 nanoparticles was significantly enhanced by V doping at a very low concentration of 0.1wt% but the response steadily degraded as the V-doping level increases further up to 2wt%. In particular, the 0.1wt% V-doped SnO2 sensor exhibited a very high response of 2274 with a short response time of 2.0s to 10ppm of H2S at 350°C. Moreover, the V-doped SnO2 sensor displayed high H2S selectivity against NO, NO2, SO2, H2, C2H5OH and CH4. Hence, the flame-made V-doped SnO2 sensor is a promising candidate for highly sensitive and selective of H2S monitoring and may be useful for general industrial applications.

A polyoxometalate-based supramolecular chemosensor for rapid detection of hydrogen sulfide with dual signals

Hydrogen sulfide (H2S) has been verified as an important biological mediator in human physiological activities, but its rapid and accurate detection is remaining a challenge. Based on our early work, Eu-containing polyoxometalate/ionic liquid-type gemini surfactant hybrid nanoparticles fabricated by EuW10O36·32H2O (Eu-POM) and 1,2-bis(3-hexadecylimidazolium-1-yl) ethane bromide ([C16-2-C16im]Br2) via ionic self-assembly (ISA) strategy, we modified the hybrids with copper (II) ion and used them as a novel turn-off supramolecular fluorescence probe for H2S immediate response. Although copper (II) ions can cause decrease of the fluorescence intensity, the probe with moderate amount of copper (II) still has a high performance in emission property. The copper (II) ion-modified supramolecular sensor (CSS) shows dual signals in the fluorescence intensity and absorbance for H2S detection, and the detection limit is about1.25μM. Furthermore, CSS displays high selectivity for H2S in the presence of other anions and species (e.g. Cl−, Br−, I−, SO42−, SO32−, S2O32−, AC−, H2O2, HCO3−, l-cysteine, homocysteine and l-glutathione), and also have potential for preferential imaging in vivo. Besides, the fluorescence quenching mechanism of CSS in the presence of H2S was explored. CuS generated by the reaction between Cu2+ and H2S was testified to act as a quencher, and the nonradiative resonance energy transfer mechanism was speculated to be responsible for fluorescence quenching. It is anticipated that the as-prepared CSS will be used as an efficient chemosensor for the rapid detection of H2S, which is critical for the diagnosis of some diseases, e.g. Alzhermer’s disease, Down’s syndrome, and diabetes, etc.

A new rosamine-based fluorescent chemodosimeter for hydrogen sulfide and its bioimaging in live cells

A new probe (RosN3), which displayed excellent selectivity to H2S in mixed aqueous media, was synthesized. This method employed the H2S-mediated reduction of azides to amines, resulting in fluorescence quenching. The probe exhibited high H2S selectivity over other common anions and biothiols. The detection limit was measured to be 0.25 μM. Furthermore, the live cell imaging results demonstrated its potential for practical application in biological systems.

A FRET-based ratiometric fluorescent probe for visualizing H2S in lysosomes

Hydrogen sulfide (H2S) is an endogenously produced gaseous signaling molecule with multiple biological functions. In order to detect the biological H2S, here a new FRET-based ratiomatric fluorescent probe was designed and synthesized for visualization of H2S in lysosomes. The probe displays good solubility, a marked yellow to blue emission color change in response of H2S and high H2S selectivity. Moreover, the probe could be used to detect of H2S in lysosomes with good biocompatibility.