High-Selectivity Hydrogen Gas Sensors based on Mesoporous PbOx -ZnO Nanocomposites.

Hydrogen heralded as a promising renewable and environmentally friendly energy carrier, carries inherent risks owing to its highly flammable nature. A mere 4 % concentration of hydrogen in the air can trigger an explosion. To counteract this peril, a composite material comprising PbOX -ZnO (2 : 1) was synthesized, characterized, and subsequently employed to fabricate a hydrogen sensing device. Various analytical tools were used to characterize as-deposited materials, including X-ray diffraction, Scanning electron microscopy /Energy Dispersive X-ray Spectroscopy, Transmission electron microscopy UV-Vis Reflectance Spectroscopy and Fourier-transform infrared spectroscopy. The device exhibited favorable properties, such as good selectivity, stability, and a low detection limit for hydrogen. At ambient room temperature, the device demonstrated a sensing signal reaching 468.7, with a response time (T90) of 155 seconds and a recovery time (Tr90) of 69 seconds when exposed to a hydrogen concentration of 5 ppm. This performance underscores the device's rapid and effective response to hydrogen exposure. Moreover, the PbOX-ZnO (2 : 1) composite-based device exhibited a detection limit of 2.4 ppm, functioning accurately within a linear range spanning from 5 ppm to 50 ppm. This capability confirms its precision in accurately detecting hydrogen concentrations within this designated range.

Enhancing Smart Sensor Tag Sensing Performance-Based on Modified Plasma-Assisted Electrochemical Exfoliated Graphite Nanosheet.

Water that penetrates through cracks in concrete can corrode steel bars. There is a need for reliable and practical seepage sensing technology to prevent failure and determine the necessary maintenance for a concrete structure. Therefore, we propose a modified plasma-assisted electrochemical exfoliated graphite (MPGE) nanosheet smart tag. We conducted a comparative study of standard and modified RFID smart tags with sensor technology for seepage detection in concrete. The performance of both smart tags was tested and verified for seepage sensing in concrete, characterized by sensor code and frequency values. Seepage was simulated by cracking the concrete samples, immersing them for a designated time, and repeating the immersing phase with increasing durations. The test showed that the modified smart tag with 3% MPGE and an additional crosslinking agent provided the best sensitivity compared with the other nanosheet compositions. The presence of 3D segregated structures on the smart tag's sensing area successfully enhanced the sensitivity performance of seepage detection in concrete structures and is expected to benefit structural health monitoring as a novel non-destructive test method.

Conductive Polymer (Graphene/PPy)-BiPO4 Composite Applications in Humidity Sensors.

In this particular experiment, a chain of conductive polymer graphene/polypyrrole (Gr/PPy) and BiPO4-or (Gr/PPy)-BiPO4-materials were prepared and used as moisture-sensitive materials. The structure and morphology of the conductive polymer (Gr/PPy)-BiPO4 materials were analyzed using an X-ray diffractometer, scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray spectroscopy. Moreover, properties such as hysteresis loop, impedance, sensing response, and response and recovery time were calculated and evaluated using an inductance-capacitance-resistance analyzer. The data expressed that PPy/BiPO4, as prepared in this study, exhibited excellent sensing properties, with impedance changing by only a few orders of range. Furthermore, the response time and time of recovery were 340 s and 60 s, respectively, and negligible humidity hysteresis occurred at different relative humidities. Therefore, conductive PPy/BiPO4, as prepared in the present study, is an excellent candidate for application in humidity sensors.

Gr/3D-ZnO Nanocomposites as Humidity Sensors with Enhanced Sensing Response.

This work introduces a novel humidity sensor based on a nanocomposite material comprising graphene decorated with three-dimensional flower-like structures of zinc oxide (Gr/3D-ZnO) fabricated via a hydrothermal method with various weight percentages of graphene. The surface structure and morphology of the Gr/3D-ZnO nanocomposite were analyzed using XRD, EDS, SEM, TEM, and Raman spectroscopy. The influence of humidity on the electrical properties of the nanocomposite was also investigated. Experiment results revealed that the nanocomposite with 70 wt% of graphene provided high sensitivity (S = 446) with rapid response times (120 s) and recovery times (160 s). These results demonstrate the excellent potential of the proposed Gr/3D-ZnO nanocomposite in monitoring atmospheric humidity. A discussion on the mechanism underlying the effects of humidity on the Gr/3D-ZnO nanocomposite is also provided.

Novel Nanoarchitechtonics Olive-Like Pd/BiVO4 for the Degradation of Gaseous Formaldehyde Under Visible Light Irradiation.

In this research, olive-like Pd/BiVO4 was successfully prepared through a facile hydrothermal coreduction method for the photocatalytic degradation of formaldehyde under visible light irradiation. The structure, composition, and optical properties of the as-prepared Pd/BiVO4 were characterized through X-ray diffraction, transmission electron microscopy, ultraviolet-visible spectrophotometry, X-ray photoelectron spectroscopy, and photoluminescence. In addition, the photocatalytic activities of Pd/BiVO4 were evaluated through the photodegradation of formaldehyde. The experimental results demonstrated that the degradation efficiency of formaldehyde increased with increasing irradiation time. Moreover, 1.0 wt% Pd/BiVO4 exhibited the highest photocatalytic performance for formaldehyde degradation in 180 min, with the formaldehyde degradation rate as high as 87.5%.

Fabrication of Nanoarchitectonic AgOx/BiPO4 Electrochemical Sensor for Detection of Resveratrol.

In the present study, a novel AgOx/BiPO4 sensor was successfully prepared and used for detecting trans-resveratrol. Prepared samples were characterized using methods including X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy. The results demonstrate that the AgOx/BiPO4 is composed of AgO, Ag2O, and BiPO4. In addition, a cyclic voltammetry method was used to measure resveratrol concentration using the electrochemical sensor based on AgOx/BiPO4. AgOx/BiPO4 presents a well-defined voltammetric peak at approximately +460 mV versus Ag/AgCl in phosphate-buffered saline solution. In addition, the sensor exhibits a detection limit of 1.0×10-7 M, and the wide dynamic concentration ranges from 2.0×10-7 to 12.5×10-6 M. Stability and interference tests were performed for 20 days. A possible mechanism for AgOx/BiPO4 detection of trans-resveratrol detection is proposed.

A Novel Co3O4-BiPO4 Nanoarchitectonics Material Preparation for the Electrocatalytic Detection of Epinephrine.

A novel sensing material of cobalt oxide-bismuth phosphate (Co3O4-BiPO4) was prepared by the hydrothermal method. Thus prepared sensing material was characterized by X-ray diffraction analysis (XRD) and transmission electron microscopy (TEM). The sensor was used for the determination of epinephrine by using modified Co3O4-BiPO4 on glassy carbon electrode (GCE). The cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods showed a wide linear response to a concentration range, from 1.71 to 55.00 µM, and the epinephrine detection limit for this sensing system was found to be 1.334 µM. The Co3O4-BiPO4 electrode has very high selectivity towards the detection of epinephrine supported by an interference test. The epinephrine sensor seems very advantageous for future clinical health and medical sectors.

Prepared Reticulated Nickel Hydroxide for Sensing Urea by Differential Pulse Voltammetry.

A urea sensor base on reticulated nickel hydroxide is prepared by hydrothermal way and operated by differential pulse voltammetry method. The reticulated nickel hydroxide has been successfully synthesized by a hydrothermal method and has been characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). The Ni(OH)2 sensor exhibits a higher sensor response (S) of 7.1 than NiO and Au sensing materials to 0.05 M urea concentration at 0.62 V. Various concentration of urea from 0.1 mM to 50 mM are performed on Ni(OH)2, and the sensor response are increased from 1.1 to 7.1 by differential pulse voltammetry (DPV) method. The urea detection limit is measured as 0.1 µM in this system. In addition, the Ni(OH)2 sensor exhibited good reproducibility and short term stability, and the response exhibits no obvious changes after 20 days tests. A possible sensing mechanism of Ni(OH)2 urea sensor is presented.

Fabrication of Pd-Pt/ZnO for High Sensitive Gaseous Formaldehyde Sensor.

In the present work, the successful fabrication of highly sensitive formaldehyde sensor based on ZnO doped Pd and Pt nanoparticles. The Pt-Pt/ZnO has been synthesized through a simple, facile and rapid method and characterized by several techniques. The fabricated Pt-Pt/ZnO exhibited a very high HCHO gas sensor response of 289.2 to 10 ppm, good selectivity and experimental detection limit of 0.5 ppm at room temperature. Response and recovery times for formaldehyde are 96 s and 46 s, respectively, at room temperature. Therefore, Pt-Pt/ZnO is a promising application in the field of detection of formaldehyde.

Promotion effect of Pd on TiO2 for visible light photocatalytic degradation of gaseous formaldehyde.

TiO2 and Pd doped TiO2 (Pd/TiO2) nanoparticles were prepared by sol gel method. Pd/TiO2 material was characterized by XRD, TEM, TPR, XPS and BET. From XRD data, the crystalline type of TiO2 is known to as Anatase type. TiO2 and Pd/TiO2 were in the order of 9-10 nm and 10-13 nm respectively. The photocatalytic activities of the TiO2 and Pd/TiO2 nanomaterials were evaluated and compared for the photodegradation of formaldehyde (HCHO). HCHO degradation on Pd/TiO2 catalyst, at 60 min, the degradation rate of gaseous HCHO is 95%. Using Pd/TiO2, the rate was faster than TiO2 or doped with other metals (Au/TiO2; Ag/TiO2; Pt/TiO2).

Promotion effect of Au on N/TiO2 for hydrogen generation from water splitting.

A series of N/TiO2 were prepared by sol gel method, which was acted as photocatalysts. These photocatalysts were characterized by Transmission Electronic Microscopy (TEM), Reflective UV-Visible spectra and X-ray diffraction (XRD). The photocatalysts were applied for hydrogen gas generation from the water splitting reaction under visible light. Various N/Ti addition ratios could change the hydrogen generation rate. For the addition ratios N/Ti = 10 of N/TiO2, we obtained the maximum hydrogen production rate is about 38 µmol h(-1) g(-1). By loading the Au into the N/TiO2, the hydrogen generation rate was increased. We could get the best hydrogen production rate of 0.05 wt% Au/N/TiO2 is about 517 µmol h(-1) g(-1).

Fast detection of local anesthetic levobupivacaine by impedance method on PPy/SWCNT.

Fast response electrochemical impedance (EI) method was developed to detect concentrations of local anesthetic Levobupivacaine. It revealed the EI method possessed fast response and recovery times and the lowest detected concentration was 1 ppm. Pyrrole was electrochemically polymerized to polypyrrole and made a composite with single walled carbon nanotubes coated over gold electrodes for sensing studies. Ppy and Ppy/SWCNT composite materials were coated upon Au electrodes and characterized by UV/Vis, Fourier Transform Infrared (FTIR), Cyclic Voltammetry (CV) and Transmission Electron Microscope (TEM). Various concentrations of levobupivacaine in the range, 1 to 500 ppm were prepared in medically significant saline solution of 0.9% NaCI as test samples. A 10-kHz frequency was used for the calibration curve, and the short response and recovery time were tested as 5 s and 3 s, respectively. The Ppy/SWCNT material with R2 as 0.9971 showed better linearity than Ppy material. Using molecular dynamic simulation studies exothermic adsorption energies and bond lengths have been calculated and explained the fast response time and lower impedance of Ppy/SWCNT than Ppy.

Promotion of generation of hydrogen by splitting of water by CNT over Pt/TiO2 catalysts.

The generation of hydrogen over CNT/Pt/TiO2 catalysts by the splitting of water under irradiation with UV light is studied. The maximum rate of evolution of hydrogen was 2300 micromolg(-1)h(-1) on 0.06 wt% Pt/TiO2 (sol-gel) and reached a stable value of approximately 2000 micromolg(-1)h(-1) when the Pt loading exceeded at a Pt loading of over 0.06 wt%. Single wall carbon nanotubes (SWCNTs) were applied to enhance the hydrogen generation activity. The evolution rate of hydrogen on 0.06 wt% Pt/0.02 wt% SWCNT-TiO2 (sol-gel) was 3836 micromolh(-1)g(-1). 0.1 M NaCI yielded more hydrogen than any other tested salt. The XRD spectra show that the crystal lattices of commercial TiO2 (ST-21) and self-made TiO2 (sol-gel method) are of the anatase form. However, the TEM images and other catalytic activity data show that the SWCNTs act as wires for the transmission of electrons.

Bis(2-chloroethoxy)methane degradation by TiO2 photocatalysis: parameter and reaction pathway investigations.

Haloethers are widely used in industry, and the release of these species into the environment is of great concern because of their toxicity and carcinogenicity. The present study deals with the photocatalytic degradation of the haloether, bis(2-chloroethoxy)methane (BCEXM), in the presence of TiO(2) particles and UV-A (lambda=365 nm) radiation. About 99.5% of BCEXM was degraded after UV irradiation for 16h. Factors such as solution pH, TiO(2) dosage, and the presence of anions were found to influence the degradation rate. To obtain a better understanding of the mechanistic details of this TiO(2)-assisted photodegradation of BCEXM with UV irradiation, the intermediates of the processes were separated, identified, and characterized by the solid-phase microextraction (SPME) and gas chromatography/mass spectrometry (GC/MS) technique. To the best of our knowledge, this is the first report on the degradation pathways of BCEXM. The first step in the destruction of BCEXM is thought to be abstraction of a hydrogen by ()OH to form a carbon-centered radical which then reacts with O(2) to form a peroxyl radical. Peroxyl radicals react with one another and produce an alkoxy radical. The beta-bond fragmentation of the alkoxy radical produces different intermediates.

Titanium dioxide-mediated heterogeneous photocatalytic degradation of terbufos: parameter study and reaction pathways.

The photocatalytic degradation of terbufos in aqueous suspensions was investigated by using titanium dioxide (TiO(2)) as a photocatalyst. About 99% of terbufos was degraded after UV irradiation for 90 min. Factors such as pH of the system, TiO(2) dosage, and presence of anions were found to influence the degradation rate. Photodegradation of terbufos by TiO(2)/UV exhibited pseudo-first-order reaction kinetics, and a reaction quantum yield of 0.289. The electrical energy consumption per order of magnitude for photocatalytic degradation of terbufos was calculated and showed that a moderated efficiency (E(EO)=71 kWh/(m(3)order)) was obtained in TiO(2)/UV process. To obtain a better understanding of the mechanistic details of this TiO(2)-assisted photodegradation of terbufos with UV irradiation, the intermediates of the processes were separated, identified, and characterized by the solid-phase microextraction (SPME) and gas chromatography/mass spectrometry (GC/MS) technique. The probable photodegradation pathways were proposed and discussed.

In situ prepared polypyrrole for low humidity QCM sensor and related theoretical calculation.

In situ preparation of polypyrrole (Ppy) by photo-polymerization coated on a quartz crystal microbalance (QCM) as a low humidity sensor was reported. Different concentrations of Ppy films say 0wt.% (as blank), 0.1, 1, and 10wt.% were investigated to measure humidity concentrations between 14.7 and 5412.5ppm(v). The adsorption/desorption behavior was also examined at humidity concentration 510.2ppm(v). The sensitivities of 0, 0.1 and 1wt.% Ppy films at 51.5ppm(v) were 0.143, 0.219 and 0.427, respectively. For 1wt.% Ppy, the highest sensitivity was obtained. The slope and correlation coefficients (R(2)) for 1wt.% Ppy at the ranges of 14.7-898.6ppm(v) were 0.0646 and 0.9909, respectively. A series of molecular simulations have been carried out to calculate bond energy for the water molecule interaction with Ppy, which was found to be approximately 3kcal/mol indicating the existence of hydrogen bonding during the sorption process. Based on Langmuir isotherm adsorption assumption, for 0.1 and 1wt.% Ppy films, the association constants were 2606.30 and 5792.98, respectively. This larger association constant for 1wt.% Ppy film explains higher sensitivity.