Dioxide Quantum Dots Research Articles

Remarkable recycling processes of conjugated polymers with titanium dioxide quantum dots as photocatalysts for photodegradation of hazardous industrial wastewater

Remarkable recycling processes of conjugated polymers with titanium dioxide quantum dots as photocatalysts for photodegradation of hazardous industrial wastewater

Improving Photocatalytic Efficiency with Titanium Dioxide Quantum Dots

Titanium dioxide quantum dots (TiO2-QDs), synthesized using a microwave-assisted method, represent a significant advancement in photocatalysis, particularly in the treatment of environmental pollutants. This study focuses on TiO2-QDs synthesized at 200°C for a duration of 5 minutes, using titanium butoxide as a precursor. Characterization through TEM, XRD, PL, and UV-Vis-DRS analyses revealed uniform quantum dots with an average size of 5.28 nm, a bandgap energy of 3.22 eV, and a crystalline anatase phase, indicative of high photocatalytic activity. Notably, these TiO2-QDs demonstrated exceptional performance in degrading methylene blue (MB) in water, achieving a remarkable treatment efficiency of 97.6% in 120 min, significantly outperforming both conventional titanium dioxide nanoparticles and commercial titanium dioxide materials. The reaction conditions were evaluated based on factors such as catalyst dose, initial MB concentration, and pH. The results indicate that optimal degradation efficiency of MB was achieved at a pH of 7, with a catalyst dose of 0.15 g/L and at a low MB concentration. The efficiency slightly decreased to 94.5% after five reuse cycles, emphasizing its significant reusability and stability. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Recycling and breakdown photodegradation processes cost of BEN-TiQD via different photodegradation processes of Brilliant Green S dye and industrial effluents

The development of efficient photocatalytic materials for environmental remediation is of paramount importance. This study reports the synthesis and characterization of novel bentonite-titanium dioxide quantum dot (BEN-TiQD) nanocomposites for the photodegradation of Brilliant Green S, a prominent industrial pollutant. The nanocomposites were prepared via a co-precipitation method, ensuring uniform dispersion of TiO2 nanoparticles on the bentonite (BEN) surface, followed by heat treatment to achieve optimal crystallinity and surface properties. Comprehensive characterization techniques, including FTIR, XRD, SEM, BET surface area analysis, and optical spectroscopy, were employed to elucidate the structural, morphological, and photophysical characteristics of the composites. The BEN-TiQD nanocomposites exhibited an augmented surface area of 277.75 m2/g, surpassing BEN alone by more than threefold, and an intermediate bandgap of 3.17 eV, rendering them suitable for visible light absorption and photocatalytic applications. The photocatalytic efficacy of BEN-TiQD was evaluated by monitoring the degradation of Brilliant Green S under various operational parameters. The nanocomposites demonstrated superior photocatalytic performance, with a rate constant of 22.24 × 10−3 s−1, significantly only lower than TiQD (28.32 × 10−3 s−1) by nearly about 21.5 %. The enhanced activity was attributed to the quantum size effect of the incorporated TiO2 quantum dots, optimizing light absorption and charge separation. Mechanistic studies revealed the generation of reactive oxygen species, particularly hydroxyl radicals, as the primary drivers of dye degradation. The reusability of BEN-TiQD was evaluated through multiple photocatalytic cycles, exhibiting remarkable stability for up to six consecutive cycles. However, a gradual decline in photodegradation efficiency was observed after prolonged sunlight exposure, likely due to particle agglomeration and reduced surface area. This research contributes to the field of environmental remediation by developing a novel composite material that synergistically combines the adsorptive properties of BEN with the photocatalytic capabilities of titanium dioxide quantum dots. The findings pave the way for further exploration and optimization of these composites for sustainable and efficient treatment of industrial dyes and effluents, addressing critical environmental challenges.

SnO2QDs: Photophysical properties, photocatalytic activity, mineralization financial cost and recycling process during industrial effluent treatment

This study investigates the synthesis, characterization, and photocatalytic performance of pure and titanium-doped tin dioxide quantum dots (SnO2QDs) prepared via a sonochemical method. The structural and morphological properties were thoroughly examined using XRD, FTIR, SEM-EDX, HRTEM, UV-DRS, and BET surface area analysis. XRD confirmed the formation of tetragonal SnO2 with high phase purity and average crystallite sizes of 2.95 nm for SnO2QD1 (calcined at 270 °C) and 8.36 nm for SnO2QD2 (calcined at 480 °C). Titanium doping was achieved without altering the SnO2 crystalline structure, as evidenced by FTIR spectra showing characteristic vibrational modes and hydroxyl groups. HRTEM images revealed spherical nanoparticles with diameters of 3.2 nm for SnO2QD1 and 9.7 nm for SnO2QD2, supported by SAED patterns confirming their polycrystalline nature. The photocatalytic efficiency was evaluated through the degradation of Reactive Yellow 145 dye under Xenon lamp irradiation. SnO2QD1 exhibited superior photocatalytic activity with a rate constant (k) of 6.94 × 10−3 s−1, achieving 80 % dye degradation in 105 min, compared to SnO2QD2 with a k of 4.50 × 10−3 s−1 and 83 % degradation in 120 min. Titanium doping further enhanced the photocatalytic performance, with SnO2QDT1 (1 % Ti) showing a k of 9.89 × 10−3 s−1 and 80 % degradation in just 90 min, three times more efficient than SnO2QDT2 (9 % Ti). BET analysis indicated a significant reduction in surface area with increased calcination temperature, from 154 m2/g for SnO2QD1 to 86 m2/g for SnO2QD2. The bandgap energies, determined via UV-DRS, were 3.30 eV for SnO2QD1 and 3.34 eV for SnO2QD2, slightly reduced in Ti-doped samples, enhancing visible light absorption. The SnO2QDs demonstrated excellent recyclability, maintaining photocatalytic activity over eight reuse cycles. Economic analysis based on Saudi Arabian electricity tariffs highlighted the cost-effectiveness of SnO2QD1, offering a 5.2 % reduction in energy consumption compared to SnO2QD2. These findings position SnO2QDs as highly efficient and sustainable photocatalysts for industrial wastewater treatment applications.

Oxygen vacancy-mediated activation of Zn-O bonds at the S-scheme heterostructure interface for efficient uranium collection and resistance to biological contamination

Efficient reduction of U(VI) to U(IV) during seawater uranium extraction remains a challenge. Here, cerium dioxide quantum dots were bonded to the surface of indium zinc sulfide (ZIS) to form ZIS composite cerium dioxide quantum dots (ZIS/QDs-Ce). The oxygen vacancies are able to activate the Zn-O bonds at the ZIS and QDs-Ce interfaces, thus enabling the constructed S-scheme heterojunction to show great potential in facilitating the separation and transfer of photogenerated carriers. ZIS/QDs-Ce exhibited high anti-bio-pollution activity by generating biotoxic free radical reactive oxygen species (ROS). The photo-induced reduction of uranium by ZIS/QDs-Ce in 10 ppm uranium spiked simulated seawater reached 99.6 %. Oxygen vacancies cause distortions in the crystal field, and the Zn-O bond activation process triggers the movement of ZIS/QDs-Ce from the singlet low-spin state to the stable triplet state, resulting in free-carrier trapping centers and optimized electronic energy band structures. ZIS/QD-Ce has superior uranium extraction capabilities and is highly recommended for uranium extraction from seawater.

Remarkable photodegradation breakdown cost, antimicrobial activity, photocatalytic efficiency, and recycling of SnO2 quantum dots throughout industrial hazardous pollutants treatment

In the conducted research, a one-step hydrothermal synthesis of pure and titanium-doped tin dioxide quantum dots is elaborated upon, with a thorough analysis of their structural, optical, morphological, and photocatalytic properties undertaken using advanced analytical techniques. Through X-ray Diffraction XRD, the crystalline nature and phase purity of the tetragonal structures of SnDs were confirmed, with the crystallite sizes measured at 3.0 nm for SnD1 and 7.66 nm for SnD2, following treatments at 240 °C and 300 °C, respectively. The structural integrity of SnO2 was maintained despite titanium doping. FTIR spectroscopy verified the existence of specific vibrational modes indicative of surface hydroxyl groups. HRTEM images revealed the spherical morphology of particles, with diameters of 3.5 nm for SnD1 and 9.1 nm for SnD2. Optical band gaps, determined through UV-DRS, ranged from 3.33 eV in SnD1 to 3.47 eV in SnDTi2. The photocatalytic degradation of Congo Red dye under xenon lamp irradiation was quantitatively assessed; notably, SnD1 exhibited a 23 % higher rate constant compared to SnD2, attributed to its smaller particle size and a 31 % greater surface area. Doping with 4 % Ti in Sn0.96Ti0.04O2 more than doubled the degradation rate compared to a 6 % Ti doping in Sn0.94Ti0.06O2. Furthermore, the generation of hydroxyl radicals was significantly enhanced, showing an increase of approximately 220 % for SnD1 and 80 % for SnD2. The capability of these nanomaterials to reduce the chemical oxygen demand of industrial organic pollutants to within regulatory limits under solar irradiation was documented, with SnD1 maintaining its photocatalytic efficiency over seven cycles of reuse. In the photocatalytic degradation rate of Congo Red dye, which was 23 % higher for SnD1 compared to SnD2, and the threefold increase in the degradation rate for SnDTi1 compared to SnDTi2. An economic assessment, based on electricity tariffs in Saudi Arabia, highlighted the cost-effectiveness of SnD1, which ranged from 26.93 to 30.36 USD per breakdown cost of the photodegradation process, showing it to be less costly than SnD2. Conversely, SnDTi1 was found to be more economical than SnDTi2, with costs ranging from 26.67 to 33.09 USD. Collectively, the results emphasize the outstanding photocatalytic performance and cost-efficiency of SnDs, reinforcing their potential as sustainable solutions for the treatment of industrial wastewater. Additionally, the antibacterial efficacy of these materials against a range of bacteria, yeast, and fungi was investigated and substantiated.

Ultrafast response humidity sensor based on titanium dioxide quantum dots/silica and its multifunctional applications

Humidity sensors with ultrafast response and recovery speed are very popular for humidity monitoring in dynamic environments such as complex operating conditions and human body monitoring. In this work, we prepared titanium dioxide quantum dots by hydrothermal synthesis and silica microspheres by Stober method. In addition, the electrostatic self-assembly method was used to prepare the two films with ultrafast response for moisture sensitivity. Due to the superhydrophilic properties of TiO2 QDs, water molecules can be adsorbed and resolved quickly on their surface. While the addition of SiO2 microspheres further increases the specific surface area of moisture-sensitive films and improves the moisture-sensitive properties of TiO2 QDs. The TiO2 QDs/SiO2 resistive humidity sensors not only exhibit excellent stability and repeatability, but also have fast water adsorption/desorption capacity. Between 11 % and 97 % relative humidity, the resistance change of the sensor reaches 6 orders of magnitude. In order to simulate the actual application environment, an experimental platform was built to verify the ultrafast response of the humidity sensor, and the response/recovery time of the sensor was as short as 22.4 ms/40.8 ms, which can quickly detect the change of humidity. The TiO2 QDs/SiO2 ultrafast humidity sensors proposed in this paper have great application potential in rapidly changing humidity environments such as complex working conditions, human body detection, humidity alarm and voice recognition.

Sustainable energy development combining natural dyes with titanium dioxide quantum dots in high-efficiency biological solar cells

Sustainable energy development combining natural dyes with titanium dioxide quantum dots in high-efficiency biological solar cells

A Stimulus-Responsive Ternary Heterojunction Boosting Oxidative Stress, Cuproptosis for Melanoma Therapy.

Cuproptosis, a recently discovered copper-dependent cell death, presents significant potential for the development of copper-based nanoparticles to induce cuproptosis in cancer therapy. Herein, a unique ternary heterojunction, denoted as HACT, composed of core-shell Au@Cu2O nanocubes with surface-deposited Titanium Dioxide quantum dots and modified with hyaluronic acid is introduced. Compared to core-shell AC NCs, the TiO2/Au@Cu2O exhibits improved energy structure optimization, successfully separating electron-hole pairs for redox use. This optimization results in a more rapid generation of singlet oxygen and hydroxyl radicals triggering oxidative stress under ultrasound radiation. Furthermore, the HACT NCs initiate cuproptosis by Fenton-like reaction and acidic environment, leading to the sequential release of cupric and cuprous ions. This accumulation of copper induces the aggregation of lipoylated proteins and reduces iron-sulfur proteins, ultimately initiating cuproptosis. More importantly, HACT NCs show a tendency to selectively target cancer cells, thereby granting them a degree of biosecurity. This report introduces a ternary heterojunction capable of triggering both cuproptosis and oxidative stress-related combination therapy in a stimulus-responsive manner. It can energize efforts to develop effective melanoma treatment strategies using Cu-based nanoparticles through rational design.

Confinement size effect on dielectric properties, antimicrobial activity, and recycling of TiO2 quantum dots via photodegradation processes of Congo red dye and real industrial textile wastewater

Abstract This article reports on the synthesis, characterization, and application of titanium dioxide quantum dots (TDS) for wastewater treatment. Three TDS samples were synthesized via a low-temperature precipitation method with calcination at 280°C (TDS1), 290°C (TDS2), and 300°C (TDS3). Characterization techniques such as X-ray powder diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy confirmed the high crystallinity, purity, and quantum confinement of the TDS with sizes of 3.1, 5.5, and 8.5 nm, respectively. The photocatalytic activity of TDS was evaluated by degrading Congo red dye under xenon lamp irradiation. TDS1, with the smallest size of 3.1 nm and the largest bandgap of 3.09 eV, showed the highest photodegradation rate of 22.49 × 10−3 S−1. TDS1 also showed effective degradation of real industrial textile wastewater under sunlight over nine repeated cycles of use. The antibacterial activity of TDS against Bacillus subtilis and Candida albicans was demonstrated, with the highest inhibition by TDS1 attributed to its higher surface area. Overall, the study shows the high photocatalytic and antimicrobial potential of synthesized TDS, especially the smallest 3.1 nm TDS1 sample. The recycling results also showcase the reusability of TDS for wastewater treatment.

Photocatalytic hydrogen peroxide production from seawater over graphitic carbon nitride supported titanium dioxide quantum dots

Photosynthesis of hydrogen peroxide (H2O2) from seawater, as a promising technique, is in infancy, and faces challenges of deactivation of photocatalyst and disturbance in H2O2 formation due to the coexisting salts in seawater. Herein, graphitic carbon nitride (g-C3N4) nanosheets supported titanium dioxide (TiO2) quantum dots (QDs) are exploited as novel and efficient photocatalysts for H2O2 photoproduction from seawater. An appropriate content of as-prepared TiO2 QDs are highly and uniformly dispersed on the surface of g-C3N4 nanosheets after a neutralization treatment. TiO2 QDs emerge the synergistic effect and the band gaps regulation effect on g-C3N4 to enhance the H2O2 production. The salt ions in the actual seawater also play the positive role. In actual seawater, the photocatalyst obtains 8.38 mM·h−1·g cat−1 of H2O2 productivity, 11.2% of apparent quantum yields (AQY), and good reusability·H2O2 productivity can be further increased into 30.15 and 23.44 mM·h−1·g cat−1, respectively in alkaline environment and with the addition of electron and proton donor ethanol in seawater. Active species and mechanism of the present photocatalytic system in seawater are also clearly clarified. TiO2 QDs supported on g-C3N4 photocatalyst achieved a major channel of two-electron reduction of O2, and an auxiliary channel of single electron reduction of O2 to produce H2O2 in seawater.

Unique properties of titanium dioxide quantum dots assisted regulation of growth and biochemical parameters of Hibiscus sabdariffa plants

Owing to the uniqueness of quantum dots (QDs) as a potential nanomaterial for agricultural application, hence in the present study, titanium dioxide quantum dots (TiO2 QDs) were successfully synthesized via sol-gel technique and the physico-chemical properties of the prepared TiO2 QDs were analyzed. Based on the results, the TiO2 QDs showed the presence of anatase phase of TiO2. TEM examination revealed spherical QDs morphology with an average size of 7.69 ± 1.22 nm. The large zeta potential value (-20.9 ± 2.3 mV) indicate greater stability of the prepared TiO2 QDs in aqueous solutions. Moreover, in this work, the application of TiO2 QDs on Hibiscus sabdariffa plants was conducted, where H. sabdariffa plants were foliar sprayed twice a week in the early morning with different concentrations of TiO2 QDs (0, 2, 5, 10, 15 and 30 ppm) to evaluate their influence on these plants in terms of morphological indexes and biochemical parameters. The results exhibited an increasing impact of the different used concentrations of TiO2 QDs on morphological indexes, such as fresh weight, dry weight, shoot length, root length, and leaf number, and physio-biochemical parameters like chlorophyll a, chlorophyll b, carotenoid contents, total pigments and total phenolic contents. Remarkably, the most prominent result was recorded at 15 ppm TiO2 QDs where plant height, total protein and enzymatic antioxidants like catalase and peroxidase were noted to increase by 47.6, 20.5, 29.5 and 38.3%, respectively compared to control. Therefore, foliar spraying with TiO2 QDs positively serves as an effective strategy for inducing optimistic effects in H. sabdariffa plants.

Electrochemiluminescence immunosensor based on tin dioxide quantum dots and palladium-modified graphene oxide for the detection of zearalenone

Developing low-cost and efficient methods to enhance the electrochemiluminescence (ECL) intensity of luminophores is highly desirable and challenging. Herein, we developed an efficient ECL system based on palladium-modified graphene oxide as a substrate and tin dioxide quantum dot-modified spike-like gold-silver alloy as an immunoprobe. Specifically, palladium-modified graphene oxide was rationally selected as the sensor substrate for the attachment of zearalenone antigens while facilitating the amplification of the ECL signal through enhanced electron transfer efficiency. A spike-like gold-silver alloy modified with tin dioxide quantum dots was attached to the zearalenone antibody as an immunoprobe, and the sensor exhibited remarkable sensitivity due to the exceptional ECL performance of the quantum dots. To demonstrate the practical feasibility of the principle, zearalenone levels were detected in actual samples of maize and pig urine, and the sensor showed a broad linear range (0.0005–500 ng mL−1) and low detection limit (0.16 pg mL−1) in the high-sensitivity detection of Zearalenone. Overall, this work first reports the construction of a highly sensitive ECL immunosensor for the detection of zearalenone using a protruding gold-silver alloy modified with tin dioxide as an immunoprobe and a palladium modified graphene oxide as a substrate. It provides a novel approach for the detection of small molecule toxin-like substances.

Distinguishable photocatalytic activity of nano polyaniline with quantum dots metal oxide as photocatalysts for photodegradation of Dianix blue dye and different industrial pollutants

Nanopolyaniline (PAN) polymers have recently been under active investigation as promising photocatalysts. In this work, a simple modified sol–gel method is used to make nano PAN polymers, and a chemical polymerization method is used to make nano polyaniline titanium dioxide quantum dots (PAN-TiQD) polymers as an active photocatalyst during the photodegradation of Dianix blue dye as an organic pollutant under xenon light. The traditional colloidal sol–gel method and the microwave-assisted hydrothermal method were used to make TiQD, which was then mixed with nanoPAN to make PAN-5 % TiQD (W/W) nanocomposites. Characterizations like XRD, FTIR, UV and visible diffuse reflectance spectra, TGA, surface area, EDX, and TEM were used to characterize the nanoPAN and PAN-TiQD that were made. Also, the photocatalytic activity of all synthesized polymers was investigated by the photodegradation process of Dianix blue dye as an organic hazardous pollutant in aqueous medium using a xenon photoreactor with an initial power of 75 W/Cm2. The effects of irradiation time and photocatalyst type on the photodegradation process efficiency of Dianix blue dye were examined. After 3 h of photodegradation processes, the photodegradation efficiency of PAN-TiQD reached 69 % compared to 36 % of nanoPAN due to the fact that it contains 5 % TiQD as a highly active catalyst, which reached 91 %. As an added value for this study, a significant contribution is the examination of eight hazardous industrial wastewater samples, which were assessed under direct sunlight and were in accordance with the KSA environmental permissible limit of 1000 ppm.Finally, the recycling processes in the presence of all synthesized catalysts were investigated and evaluated six times. The photodegradation rate of the recycling processes of Dianix blue dye was highly decreased in the presence of nano PAN than PAN-TiQD, while it had a low decreasing percentage in the case of TiQD. The recycling process using sunlight for industrial pollution samples was investigated at one of the KSA textile plants by using six synthetic catalysts and assessing COD and TOC values.

Remarkable photocatalytic activity of poly2-chloroaniline and poly 2-chloroaniline titanium dioxide quantum dots for photo-degradation of organic hazardous materials.

Remarkable photocatalytic activity of poly2-chloroaniline and poly 2-chloroaniline titanium dioxide quantum dots for photo-degradation of organic hazardous materials.

Poly ortho-chloroaniline and poly ortho-chloroaniline titanium dioxide quantum dots for photo-degradation of organic hazardous materials

Conjugated polymers have recently been under active investigation as promising alternatives to use in photocatalysis. This is due to their unique advantages of low cost, high chemical stability, and molecularly tunable optoelectronic properties. This work explores the easy way to synthesize efficient poly ortho-chloroaniline (pO-CAN) via the chemical oxidative polymerization of O-CAN. Titanium dioxide quantum dots (TiQD) have been prepared and used in preparation of (pO-CAN)/TiQD. X ray diffraction, FTIR, UV &Visible spectra, TGA, surface area, EDX and TEM measurements were used to characterize all prepared polymers. The photocatalytic activities of all recent polymers were investigated by the photodegradation of methyl orang dye as an organic hazardous chemical in an aqueous medium was assessed using a 100-watt xenon lamp light source and direct sunlight for industrial wastewater samples. The effect of irradiation time on photodegradation performance of the dye in presence of recent polymers. (pO-CAN)/TiQD demonstrated high photocatalytic properties, with 79.9 % efficiency, as opposed to 48.8 % for (pO-CAN) only while it is 92.8 % for TiQD. When (pO-CAN), TiQD, and (pO-CAN)/TiQD are present during the recycling processes in the presence of all created samples up to six times, the photodegradation rate decreases by about 57.18, 9.61 and 9.51 % respectively. Also, the recycling and photodegradation performance of the industrial wastewater samples were evaluated and observed interested results.

Distinguishable Recycling and Photodegradation Processes of Real Industrial Effluents and Blue Dianix Dye in the Presence of Different TQDs Size

Three titanium dioxide quantum dots (TQDs) samples were successfully synthesized at low calcination temperatures via a modified precipitation method at T1 = 330, T2 = 360, and T3 = 400 °C. The synthesized TQDs samples were characterized by: XRD, FE-SEM, HRTEM, and EDX to analyze the crystallinity, purity, and existence of asymmetric circle forms for the TQDs catalysts. Also, the surface area, band gap energy, and crystallite size at different calcination temperatures are 322.32 m2/g, 3.20 eV, and 4.9 nm at 300 °C, 292.39 m2/g, 3.14 eV, and 5.4 nm at 360 °C, and 254.66 m2/g, 3.07 eV, and 6.2 nm at 400 °C, respectively. A xenon photoreactor (70 W/cm2) was used to evaluate the photodegradation process of Blue Dianix dye and sunlight for real industrial effluent treatment. The photocatalytic activity decreases as the crystallite size increases in the TQD samples. Photocatalytic activity of TQDs due to their distinguishable crystalline domain size of less than 10 nm and their high surface area. The photodegradation rate of real industrial effluents was evaluated according to the COD limits permitted by Egyptian environmental law. Also, TOC and COD analyses evaluated 12 recycled samples of TQDs.

Recycling and photodegradation processes of organic hazardous materials on polyaniline-titanium dioxide quantum dots catalyst

A photo-catalyst with conducting polymers doped with titanium dioxide, known as TiO2 quantum dots (TiO2 QDs), has a high efficiency for photocatalytic usage. The organic hue methyl orange was broken down in the current study using polyaniline (PANI) and polyaniline titanium dioxide quantum dots (PANI-TiO2 QDs) polymers. PANI and PANI-TiO2 QDs have been produced by chemical oxidative polymerization in an aqueous solution. By characterization of PANI-TiO2 QDs nanocomposites using ultraviolet–visible (UV–vis), Fourier transform infrared (FTIR), and X-ray powder diffraction (XRD), it was demonstrated that the chemical structure of polymer composites had not changed after being doped with TiO2 QDs. To determine the form, size, surface area, and thermal analyses of the produced PANI-TiO2 QDs samples, EDX, BET, and TGA were used. The photocatalytic activity of the PANI-TiO2 QDs in the photo-degradation of methyl orange dye as an organic hazardous chemical in an aqueous medium was assessed using a 50-watt xenon lamp light source and direct sunlight. PANI-TiO2 QDs demonstrated high photocatalytic properties, with a 93% efficiency, as opposed to 35% and 60.1%, respectively, for PANI and TiO2 QDs. When PANI, titanium dioxide quantum dots, and PANI-TiO2 QDs are present during the recycling processes in the presence of all created samples up to four times, the photo-degradation rate decreases by about 50.2%, 15.4%, and 17.4%, respectively.

Room-temperature flexible ammonia sensor based on SnO2 quantum dots modified graphene oxide

Tin dioxide quantum dots (SnO2 QD) were prepared by hydrothermal method, and then SnO2 QD modified graphene oxide (SnO2 QD@GO) was synthesized by a secondary hydrothermal technique to fabricate a flexible sensor for detecting ammonia at room temperature. The morphology, structure and composition of the composites were analyzed by SEM, TEM, EDS, XPS, XRD and Raman spectroscopy. TEM images showed that SnO2 QD with a diameter range of 5–8 nm present a cuboid structure, embedded in the two-dimensional GO surface. The gas sensing test shows that at room temperature the response of SnO2 QD@GO to ammonia is 5 times higher than that of GO. At the same time, the operating temperature of pure SnO2 QD is greatly reduced from 250 °C to room temperature (24 °C) by the composing of GO. Flexibility test of SnO2 QD@GO was also measured to test the fatigue resistance and bending test of the device. The improved ammonia sensing performance of SnO2 QD@GO is mainly due to the smaller bond energy of ammonia and abundant functional groups of GO, which provides more active sites for the surface adsorption of NH3.

Construction of ultra-fast hydrogen sensor for dissolved gas detection in oil-immersed transformers based on titanium dioxide quantum dots modified tin dioxide nanosheets

Hydrogen (H2) is a typical product dissolved in transformer oil and a typical fault diagnosis gas for oil-immersed transformer equipment. The large concentration range and fast detection of H2 gas sensors have certain engineering significance. In this paper, TiO2 quantum dots (QDs) with particle size of about 5 nm were prepared by solvothermal reaction, and SnO2 nanosheets modified by TiO2 QDs was successfully prepared. The gas sensing performance of TiO2-SnO2 to H2 was systematically explored. The optimal operating temperature of the sensors is 400 °C. At the optimal operating temperature of 400 °C, the TiO2 (1 %)-SnO2 sensor demonstrated the most excellent gas sensing performance to H2, such as the short response and recovery time (2 s and 5 s to 200 ppm H2), excellent stability, outstanding selectivity and large detection range of 4.8–5000 ppm. The first-principles calculations were carried out and the gas sensing mechanism was further elaborated, which show that the improvement of the TiO2(1 %)-SnO2 is mainly ascribed to the sensitization and homojunction effect of TiO2 QDs. The TiO2 (1 %)-SnO2 gas sensor is expected to provide a choice for the dissolved gas analysis (DGA) method in transformer oil analysis.