Dual-wavelength electrochemiluminescence ratiometry of hydrogen sulfide based on Cd2+-doped g-C3N4 naonsheet

Herein, a novel and facile dual-wavelength ratiometric electrochemiluminescence-resonance energy transfer (ECL-RET) sensor for hydrogen sulfide (H2S) detection was constructed based on interaction between S2- and Cd2+-doped g-C3N4 nanosheets (NSs). Cd2+-doped...

Nanocrystalline SnO2 Functionalized with Ag(I) Organometallic Complexes as Materials for Low Temperature H2S Detection

This paper presents a comparative analysis of H2S sensor properties of nanocrystalline SnO2 modified with Ag nanoparticles (AgNPs) as reference sample or Ag organic complexes (AgL1 and AgL2). New hybrid materials based on SnO2 and Ag(I) organometallic complexes were obtained. The microstructure, compositional characteristics and thermal stability of the composites were thoroughly studied by X-ray diffraction (XRD), X-ray fluorescent spectroscopy (XRF), Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and Thermogravimetric analysis (TGA). Gas sensor properties to 2 ppm H2S demonstrated high sensitivity, selectivity toward other reducing gases (H2 (20 ppm), NH3 (20 ppm) and CO (20 ppm)) and good reproducibility of the composites in H2S detection at low operating temperatures. The composite materials also showed a linear detection range in the concentration range of 0.12–2.00 ppm H2S even at room temperature. It was concluded that the predominant factors influencing the sensor properties and selectivity toward H2S in low temperature region are the structure of the modifier and the chemical state of silver. Thus, in the case of SnO2/AgNPs reference sample the chemical sensitization mechanism is more possible, while for SnO2/AgL1 and SnO2/AgL2 composites the electronic sensitization mechanism contributes more in gas sensor properties. The obtained results show that composites based on nanocrystalline SnO2 and Ag(I) organic complexes can enhance the selective detection of H2S.

Highly sensitive fiber-optic SPR sensor with surface coated TiO2/MWCNT composite film for hydrogen sulfide gas detection

Hydrogen sulfide (H2S) gas poses a severe effect on the respiratory system of the human body and ambient environment, necessitating development of on-line H2S gas sensors with high performance for safety and health concerns. Here, we proposed a fiber-optic surface plasmon resonance (SPR) sensor for H2S detection employing TiO2nanoparticles and multilayer carbon nanotubes composite (TiO2/MWCNT) as sensing film, featuring desirable advantages of highly sensitivity, selectivity, and real-time detection. Benefiting from special structure and large specific surface area of MWCNTs, the adsorption capacity of sensing surface to gas molecules can be significantly enhanced. Moreover, the high carrier mobility of MWCNTs can further promote the charge transfer between TiO2 and H2S. These unique features of TiO2/MWCNT composite film result in an obvious improvement of sensitivity for H2S detection. Experimental results show that the maximum sensitivity of 21.76 pm/ppm and detection limit of 0.2 ppm can be obtained by appropriately optimizing the componential constitutions of TiO2/MWCNT composite. Such detection limit is strikingly lower than the threshold concentrations in workplace set by Federal Institute for Occupational Safety (10 ppm). In addition, the favorable selectivity, response/recovery times, repeatability and stability were demonstrated as well. This facile and cost-effective work provides a novel strategy for constructing high performance H2S gas sensor with fast response and real-time detection, which has prospective application in the fields of human health and environmental conservation.

Comparison of Online Sensors for Liquid Phase Hydrogen Sulphide Monitoring in Sewer Systems

Hydrogen sulfide (H2S) related to wastewater in sewer systems is known for causing significant problems of corrosion and odor nuisance. Sewer systems severely affected by H2S typically rely on online H2S gas sensors for monitoring and control. However, these H2S gas sensors only provide information about the H2S emission potential at the point being monitored, which is sometimes inadequate to design control measures. In this study, a comparison of three market-ready online sensors capable of liquid-phase H2S detection in sewer systems was assessed and compared. Two of the three sensors are based on UV/Vis spectrophotometry, while the other adapted the design and principles of a Clark-type electrochemical microsensor. The H2S measurements of the sensors were statistically compared to a standard laboratory method at first. Following that, the performance of the online sensors was evaluated under realistic sewer conditions using the Berlin Water Company (BWB) research sewer pilot plant. Test applications representing scenarios of typical H2S concentrations found in sulfide-affected sewers and during control measures were simulated. The UV/Vis spectrometers showed that the performance of the sensors was highly dependent on the calibration type and measurements used for deriving the calibration function. The electrochemical sensor showed high sensitivity by responding to alternating anaerobic/anoxic conditions simulated during nitrate dosing. All sensors were prone to measurement disturbances due to high amounts of sanitary solids in wastewater at the study site and required continuous maintenance for reliable measurements. Finally, a summary of the key attributes and limitations of the sensors compared for liquid phase H2S detection is outlined.

CuxO Nanostructure-Based Gas Sensors for H2S Detection: An Overview

H2S gas is a toxic and hazardous byproduct of the oil and gas industries. It paralyzes the olfactory nerves, with concentrations above 100 ppm, resulting in loss of smell; prolonged inhalation may even cause death. One of the most important semiconducting metal oxides for the detection of H2S is CuxO (x = 1, 2), which is converted to CuxS upon exposure to H2S, leading to a remarkable modulation in the resistance and appearance of an electrical sensing signal. In this review, various morphologies of CuxO in the pristine form, composites of CuxO with other materials, and decoration/doping of noble metals on CuxO nanostructures for the reliable detection of H2S gas are thoroughly discussed. With an emphasis to the detection mechanism of CuxO-based gas sensors, this review presents findings that are of considerable value as a reference.