Detection Of Formaldehyde Research Articles

Effect of in doping on the formaldehyde sensing performance of ZnSnO3 cubes ceramics

In this paper, Zn1-xInxSnO3 cubes were synthesized by a simple co-precipitation method, and the morphology and structure of the samples were characterized by various techniques. The results show that Zn1-xInxSnO3 has a regular cube structure with a size range of 900–1000 nm. It is obtained by N2 absorption and BET calculation that doping In element improves the specific surface area of the material, promotes the reaction between the measured gas and the gas-sensing material, and thus improves the gas-sensing property of the material. The gas-sensing test results indicate that contrasted with the pure ZnSnO3 sample, the optimal operating temperature of the Zn1-xInxSnO3 (ZISO) sample is reduced (200 °C), and the response value is improved. Especially, Zn0·95In0·05SnO3 (ZISO-5) showed a significantly improved response to 100 ppm formaldehyde gas at the optimum operating temperature of 200 °C, which provided rapid, real-time and efficient technical support for formaldehyde detection. In addition, we also discuss the gas-sensing mechanism of the Zn1-xInxSnO3 cube obtained by In doping to formaldehyde. This study provides technical support and theoretical basis for the optimization of gas-sensing property of ZnSnO3 gas-sensing materials.

Highly selective gas sensors for formaldehyde detection based on ZnO@ZIF‑8 core-shell heterostructures

Formaldehyde is a hazardous volatile organic pollutant commonly found indoors, making selective and accurate detection of formaldehyde crucial. To achieve this, ZnO@ZIF-8 core-shell heterostructures were fabricated using the sacrificial template method, where the 3D ZnO flower-like structures served as the core material. This innovative approach utilizing the ZIF-8 shell as a “selective gas filter” offers a novel pathway for enhancing the selectivity of formaldehyde sensors. Subsequent investigations revealed that the thickness of the ZIF-8 shell significantly influences the material’s performance. Among various configurations tested, the 2-ZnO@ZIF-8 sensor demonstrates the best formaldehyde detection properties, including high response (5 ppm, 5.03), excellent selectivity, short response and recovery times (29/40 s), excellent long-term stability, and a low theoretical detection limit (12.86 ppb) at 175 °C. The enhanced sensing properties can be attributed to the ZIF-8 surface’s high adsorption energy for formaldehyde molecules and the selective screening of gas molecules by ZIF-8. Overall, our study presents a promising strategy for developing highly selective gas sensors for formaldehyde detection, with the potential to contribute to improved indoor air quality monitoring and safety measures.

Single atom Rh-sensitized SnO2 via atomic layer deposition for efficient formaldehyde detection

Single atom catalysts (SACs) have demonstrated great potential in detection of toxic volatile organic compounds (VOCs) because of their high catalytic efficiency and unique electronic and chemical properties. In this study, we report an extremely sensitive and selective formaldehyde gas sensor based on single atom Rh-sensitized SnO2 nanoparticles prepared by atomic layer deposition (ALD). Gas sensing investigations demonstrate that the SnO2/Rh sensor has a response of 36.3 to 20 ppm formaldehyde, showing a nearly 23-fold enhancement over pure SnO2, as well as high sensitivity, fast response-recovery time (4–29 s) and excellent selectivity. DFT calculations reveal that the atomic Rh dramatically increases the adsorption and charge transfer between formaldehyde molecules and SnO2. By using the developed sensor, a portable formaldehyde detection device has been designed, which indicates a great prospect of our strategy in practical sensors.

High performance porous LaFeO3 gas sensor with embedded p-n junctions enabling ppb-level formaldehyde detection

Metal oxides based semiconductors promise high performance gas sensing owing to their robustness and low cost, but are limited by their unsatisfied adsorption ability and intrinsic low carriers' mobility. We herein demonstrate an efficient strategy of reducing the adsorption energy and improving the carrier mobility via bulk implanted TiO2 nanocrystals (NCs) in LaFeO3 porous structure. By implanting laser generated sub-3 nm TiO2 NCs in LaFeO3 samples, the response value (221.8 for 100 ppm formaldehyde) increases about 4 times comparing with that of pristine. Additionally, the sample exhibits high sensitivity and fast response/recovery speed toward formaldehyde steam. The detailed analyses and theoretical calculation proves that the TiO2 NCs could cause the increase of adsorbed oxygen levels as well as the carrier mobility through forming the heterojunction with LaFeO3. This work verifies that TiO2 NCs implanted LaFeO3 is a promising formaldehyde sensing material, which provides a new approach to improve sensing ability of metal oxide semiconductor (MOS) based gas sensors.

Detection of formaldehyde contaminated in squid from fresh markets in Muang District Nakhon Ratchasima Province, Thailand

Detection of formaldehyde contaminated in squid from fresh markets in Muang District Nakhon Ratchasima Province, Thailand

Synergistic effects of Mg doping on TiO2 for improved toxic gas sensing performance at room temperature

The gas sensing characteristics of magnesium (Mg)-doped titanium dioxide (TiO2) films were investigated using a spray pyrolysis method. TiO2 Thin films with varying Mg doping concentrations (0, 2.5, and 5 weight percentages) were deposited and tested for their gas detection ability to organic compounds such as ethanol, butanol, toluene, xylene, and formaldehyde at room temperature. Results disclosed that introducing Mg into TiO2 enhanced the gas sensing characteristics, particularly for formaldehyde. Mg-doped TiO2 film improved the change in electrical resistance during gas adsorption, leading to an increased response in formaldehyde detection. Additionally, XRD revealed the crystal structure, while Raman spectroscopy provided insights into molecular vibrational modes of the fabricated films. FESEM allowed for high-resolution imaging of surface morphology, and atomic force microscope assessed surface roughness and other properties of the as deposited samples. UV-Vis spectroscopy was utilized to examine the optical characteristics. The collective results strongly indicated that the introduction of Mg significantly improved the gas-sensing capabilities of TiO2 films, making them highly promising for various gas-sensing applications.

Quantitative detection of formaldehyde using solid phase microextraction gas chromatography–mass spectrometry coupled to cysteamine scavenging

Formaldehyde (HCHO) is a toxic and carcinogenic pollutant and human metabolite that reacts with biomolecules under physiological conditions. Quantifying HCHO is essential for ongoing biological and biomedical research on HCHO; however, its reactivity, small size and volatility make this challenging. Here, we report a novel HCHO detection/quantification method that couples cysteamine-mediated HCHO scavenging with SPME GC–MS analysis. Our NMR studies confirm cysteamine as an efficient and selective HCHO scavenger that out-competes O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine, the most commonly used scavenger, and forms a stable thiazolidine amenable to GC–MS quantification. Validation of our GC–MS method using FDA and EMA guidelines revealed detection and quantification limits in the nanomolar and micromolar ranges respectively, while analysis of bacterial cell lysate confirmed its applicability in biological samples. Overall, our studies confirm that cysteamine scavenging coupled to SPME GC–MS analysis provides a sensitive and chemically robust method to quantify HCHO in biological samples.

In Situ Fabrication of SnS2/SnO2 Heterostructures for Boosting Formaldehyde-Sensing Properties at Room Temperature.

Formaldehyde, as a harmful gas produced by materials used for decorative purposes, has a serious impact on human health, and is also the focus and difficulty of indoor environmental polution prevention; hence, designing and developing gas sensors for the selective measurement of formaldehyde at room temperature is an urgent task. Herein, a series of SnS2/SnO2 composites with hollow spherical structures were prepared by a facile hydrothermal approach for the purpose of formaldehyde sensing at room temperature. These novel hierarchical structured SnS2/SnO2 composites-based gas sensors demonstrate remarkable selectivity towards formaldehyde within the concentration range of sub-ppm (0.1 ppm) to ppm (10 ppm) at room temperature. Notably, the SnS2/SnO2-2 sensor exhibits an exceptional formaldehyde-sensing performance, featuring an ultra-high response (1.93, 0.1 ppm and 17.51, 10 ppm), as well as good repeatability, long-term stability, and an outstanding theoretical detection limit. The superior sensing capabilities of the SnS2/SnO2 composites can be attributed to multiple factors, including enhanced formaldehyde adsorption, larger specific surface area and porosity of the hollow structure, as well as the synergistic interfacial incorporation of the SnS2/SnO2 heterojunction. Overall, the excellent gas sensing performance of SnS2/SnO2 hollow spheres has opened up a new way for their detection of trace formaldehyde at room temperature.

Construction of hexagonal hollow rod-shaped NiCo2O4–In2O3 p-n heterojunction for low concentration formaldehyde detection

The construction of p-n heterostructures using n-type and p-type semiconductor is a very important way to enhance gas sensing performance. In this work, hexagonal rod-shaped NiCo2O4/In2O3 with larger surface area was prepared via a simple water bath approach and subsequent calcination process. The microscopic morphology characterization results show that the NiCo2O4/In2O3 composite has a hexagonal hollow rod-shaped structure, where NiCo2O4 grows in situ on the surface of In2O3, forming p-n heterojunctions. Notably, the NiCo2O4/In2O3 composites formed with 6% NiCo2O4 addition (In-NC6) at 200 °C showed the best gas sensing performance for 1 ppm formaldehyde with a response value of 9.11 and a theoretical detection limit as low as 10.83 ppb. The rich oxygen vacancies, active site and p-n heterojunction are conducive to the adsorption of formaldehyde and electron transfer. This in situ growth approach provides novel ideas and promising prospects to synthesize other p-n heterojunction materials for applying to toxic gas detection.

Ratiometric lysosome-targeting luminescent probe based on a coumarin-ruthenium(II) complex for formaldehyde detection and imaging in living cells and mouse brain tissues.

Ratiometric luminescence probes have attracted widespread attention because of their self-calibration capability. However, some defects, such as small emission shift, severe spectral overlap and poor water solubility, limit their application in the field of biological imaging. In this study, a unique luminescence probe, Ru-COU, has been developed by combining tris(bipyridine)ruthenium(II) complex with coumarin derivative through a formaldehyde-responsive linker. The probe exhibited a large emission shift (Δλ>100nm) and good water solubility, achieving ratiometric emission responses at 505nm and 610nm toward formaldehyde under acidic conditions. Besides, ratiometric luminescence imaging of formaldehyde in living cells and Alzheimer disease mouse's brain slices demonstrates the potential value of Ru-COU for the diagnosis and treatment of formaldehyde related diseases.

Highly Sensitive Detection of Formaldehyde by Laser-Induced Graphene-Coated Silver Nanoparticles Electrochemical Sensing Electrodes.

Formaldehyde (HCHO) poses a grave threat to human health because of its toxicity, but its accurate, sensitive, and rapid detection in aqueous solutions remains a major challenge. This study proposes a novel electrochemical sensor composed of a graphene-based electrode that is prepared via laser induction technology. The precursor material, polyimide, is modified via the metal ion exchange method, and the detective electrode is coated with graphene and silver nanoparticles. And the special structure of graphene-coated Ag was demonstrated using scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM), and X-ray diffraction (XRD), Fourier transform infrared (FT-IR), and X-ray photoelectron spectroscopy (XPS) results show that graphene provides more sites for Ag NRs to be exposed and increases the surface area of contact between the solution and the detection object. In addition, differential pulse voltammetry (DPV) analysis exhibits high linearity over the HCHO concentration range from 0.05 to 5 μg/mL, with a detection limit of 0.011 μg/mL (S/N = 3). The Ag NPs in the electrochemical reaction will adsorb the intermediate •CO and •OH, catalyze their combination, and finally convert to CO2 and H2O, respectively. A microdetection device, specially designed for use with commercial micro-workstations, is employed to fully demonstrate the practical application of the electrode, which paves a way for developing formaldehyde electrochemical sensors.

Fe-doped ZnSnO3 cubes for high-performance detection of formaldehyde

ZnSnO3 is a typical metal semiconductor oxide (MOS), which has wide-band gap, n-type transport characteristics and excellent gas sensing performance. Fe doping plays a pivotal role in enhancing the formaldehyde sensing performance of ZnSnO3. In this paper, Fe-doped ZnSnO3 cubes were prepared successfully by a simple co-precipitation method. A series of characterization results show that Fe-doped ZnSnO3 is a cubic structure with uniform size of about 1.1 μm, and Fe doping increases the specific surface area and oxygen vacancy, which is responsible for the enhanced sensing performance. The gas-sensing tests show that Fe-doped ZnSnO3 cubes have a significant selectivity for formaldehyde gas, and the response value of Fe-doped ZnSnO3 cubes (3 mol%) to 100 ppm formaldehyde gas is about 5 times that of pure ZnSnO3 at 200 °C. In addition, the sensor has a fast response/recovery time (12/12 s), good recovery and reproducibility. Its excellent sensing performance is attributed to Fe doping, which leads to more defects and active sites in Fe-doped ZnSnO3 gas sensor. This work confirms that Fe-doped ZnSnO3 is a promising preparation scheme for formaldehyde sensors.

Au modified SnO2 submicron flowers sensor for efficient detection of formaldehyde and its application in detection of green vegetables

Au modified SnO2 submicron flowers were successfully synthesized through hydrothermal route and calcination process. The morphology, microstructure and optical properties were thoroughly investigated. The gas sensing performance of pristine SnO2 and Au modified SnO2 were investigated towards different concentrations of formaldehyde gas. Remarkably, the sensor based on Au/SnO2-2 exhibits high response, fast response/recovery speed, excellent selectivity and stability. The formaldehyde sensing mechanism was also discussed in depth. Furthermore, the practical application test in bagged baby cabbage was performed after the vegetable was soaked in the formaldehyde solution.

Highly selective detection of formaldehyde and its analogs in clams based on unique and specific conjugation reactions via ultraviolet-visible absorptions

Although formaldehyde has been widely used in industry, the excessive or residual formaldehyde has been proven to cause irreversible harm to human beings due to its high toxicity. To solve this problem, we studied oxalyldihydrazide as an analytical reagent to determine formaldehyde by ultraviolet and visible (UV-vis) spectrophotometry. In this study, hydrazine compounds with –NH–NH2 structures can react with formaldehyde to form hydrazone (including –NH–N=CH–), water is the only by-product. Therefore, oxalyldihydrazide can not only react with formaldehyde but also sense its analogs such as acetaldehyde, acetone, and benzaldehyde in solution, and detect them by UV-vis spectrophotometry at 220 nm, 226 nm, 262 nm, and 257 nm respectively. Among them, the limit of detection (LOD) of formaldehyde is calculated to be 0.03 ppm (LOQ = 0.03 ppm) with the relative standard deviation (RSD) of 1.58%. Meanwhile, the above-mentioned method can be used for detecting formaldehyde in clams with excellent selectivity and sensitivity.

Study on the color-changing mechanism and law of visual formaldehyde sensing system based on hyperbranched polyamines

This study focuses on addressing the limitations associated with most chemical derivatization methods commonly used for formaldehyde detection. These methods often suffer from prolonged derivative times (≥30 min) and complex procedures, which hinder their ability to meet the requirements of real-time and accurate sensing. In this research, a novel formaldehyde indicator system based on hyperbranched polyamine molecule was developed, and its mechanism and principles of color change were investigated. The findings revealed that hyperbranched polyamine molecule effectively reacts with formaldehyde, leading to a reduction in electron cloud density in the amine group N and subsequently causing a decrease in pH value. This reaction enables the visualization of formaldehyde detection through changes in the indicator spectrum. Moreover, the spectral variation pattern exhibits a strong linear correlation with the formaldehyde concentration when the PAMAM concentration is optimized. The detection limit of this method was determined to be 1.8 ppm. Notably, the reaction between PAMAM and formaldehyde is almost instantaneous, the color change is insensitive to temperature, and the method demonstrates high selectivity. Overall, this research contributes to the advancement of real-time formaldehyde monitoring technology and provides insights for future developments in this field.

Construction of Flower-like ZnO Nanoclusters on Functionalized Graphene Nanosheets for Room Temperature Formaldehyde Sensing

Background: Formaldehyde (HCHO) is one of the sources of indoor air pollution and a recognized carcinogenic gas, which sets a huge threat to human health. Therefore, it is urgent to develop a formaldehyde gas sensor with high efficiency, low consumption, and low limit of detection. Methods: With solvothermal and supramolecular assembly methods, we fabricate a nanocomposite of ZnO/5-aminonaphthalene-1-sulfonic acid (ANS)-reduced graphene oxide (rGO) through in situ assembling flower-like ZnO nanoclusters on ANS-modified graphene nanosheets for room temperature formaldehyde detection. Results: The flower-like ZnO/ANS-rGO based gas sensor exhibits high response (32%, 5 ppm), ultra-fast response/recovery times (18/23 s), high selectivity, long-term stability and a low practical limit of detection (pLOD) of 1 ppm toward HCHO at room temperature, offering significant advantages and competitiveness in chemiresistive room temperature HCHO sensors. Conclusion: The unique flower-like nanostructure of ZnO and the functionalization with ANS molecules jointly improved the HCHO sensing performance of the composite at room temperature. This work provides a new approach to designing and preparing high-performance room temperature gas sensing materials.

Highly sensitive and selective detection of benzene, toluene, xylene, and formaldehyde using Au-coated SnO2 nanorod arrays for indoor air quality monitoring

We report the high performance of Au-coated SnO2 nanorod gas sensors for the detection of hazardous indoor volatile organic compounds (VOCs), such as benzene, toluene, xylene, and formaldehyde (BTXF) gases. Densely ordered SnO2 nanorod arrays were prepared via glancing angle deposition with an electron beam evaporator. The Au layer coating was used as a heterogeneous catalyst to promote the oxidation of VOCs, such as hydrocarbons. After optimizing the Au thickness, the sensor exhibited an excellent sensing response and a rapid response time of < 2.5 s for 10 ppm of BTXF gases. The maximum response was ∼662 for formaldehyde at 400 °C, ∼328 for toluene at 450 °C, ∼170 for xylene at 400 °C, and ∼139 for benzene at 500 °C, which are significantly higher than those of previously reported metal-oxide-semiconductor-based sensors. Each gas was selectively detected by integrating the sensor into a miniaturized gas chromatography (GC) system. The sensors detected ppb-level gas concentrations. Significantly, GC analysis revealed that four types of gases could be separately detected in a mixed gas within 5 min. Our study shows that Au-coated SnO2 nanorod gas sensors integrated with GC can be used as a facile indoor pollutant monitoring system.

Self-assembled nano-particles of chitosan amphiphilic derivative for formaldehyde fluorescent detection and its application in test strips

Excessive levels of formaldehyde (FA) represent serious health risks. Aiming at the detection of formaldehyde content, this paper proposes a self-assembly method of proportional nanoprobes. Spherical nanoparticles (NPs) were prepared by one-step condensation reaction between rhodamine B (RhB) and chitosan (CS). After CS was modified by RhB, the linear structure changed and self-assembled under the action of “hydrophilic/hydrophobic” to form a core-shell structure with a cavity structure. The hydrophobic small molecule probe N-Butyl-4-Hydrazo-1,8-Naphacticimide (NBHN) spontaneously entered into the hydrophobic cavity to form spherical particles Chitosan-Rhodamine B@N-Butyl-4-Hydrazo-1,8-Naphacticimide (CS–RhB@NBHN) with a size of about 60 nm. The hydroxyl groups on CS enrich formaldehyde through charge interaction, and promote the reaction of formaldehyde with NBHN, so that the probe can detect formaldehyde at a lower concentration (detection limit 87 nmol·L−1). The self-assembled CS-RhB@NBHN nanoparticles significantly increased the response speed of NBHN (from 30 min to 10 min). After the reaction of NBHN with formaldehyde, the PET effect is released, the fluorescence transition from red to yellow of CS-RhB@NBHN, and the visual fluorescence response effect to formaldehyde is significantly improved. With the help of smartphone color recognition software, we converted the color of the probe solution into RGB values to realize the quantitative and visual detection of formaldehyde. In addition, CS-RhB@NBHN was used for the detection of FA in leather and air.

A dual-function fluorescent probe for the detection of pH values and formaldehyde.

A dual-function fluorescent probe (Probe 1) was developed in this work for the separate detection of pH value and formaldehyde (HCHO). Probe 1 could recognize HCHO and the pH value from the amino group. The colour of the probe solution was changed from grey blue to light blue with the increase in the pH value, and luminous intensity became larger with the increase in formaldehyde concentration. The curve function relationship between fluorescence intensity and the pH value was also determined. A smartphone containing a colour detector for imaging was used to record the values of the three primary colours (R value, G value, and B value) for the probe solution in formaldehyde. Importantly, there was a linear functional relationship between the B*R/G value with HCHO concentration. Therefore, the probe could be used as a rapid tool for the detection of formaldehyde. More importantly, Probe 1 was successfully used to detect formaldehyde in an actual distilled liquor sample.

A simple quinolimide-based fluorescent sensor for formaldehyde and its applications in test strips and living cells

A simple fluorescent sensor H2 containing quinolimide as a fluorophore and hydrazine as a reaction site was designed and synthesized for the detection of formaldehyde (FA). H2 had the high selectivity and sensitivity to FA through the pseudo-first-order reaction (k = 0.048 min−1), exhibiting the significantly enhanced fluorescence signal. The quantitative determination range of H2 for FA was 0–180 μM, and the LOD of FA is 1.7 μM. Moreover, H2-loaded test strips were demonstrated in the visualization of sensing FA. And H2 was successfully applied for imaging FA in living cells.