SnO2 Quantum Dots Research Articles

High-Performance Ammonia QCM Sensor Based on SnO2 Quantum Dots/Ti3C2Tx MXene Composites at Room Temperature.

Ammonia (NH3) gas is prevalent in industrial production as a health hazardous gas. Consequently, it is essential to develop a straightforward, reliable, and stable NH3 sensor capable of operating at room temperature. This paper presents an innovative approach to modifying SnO2 colloidal quantum dots (CQDs) on the surface of Ti3C2Tx MXene to form a heterojunction, which introduces a significant number of adsorption sites and enhances the response of the sensor. Zero-dimensional (0D) SnO2 quantum dots and two-dimensional (2D) Ti3C2Tx MXene were prepared by solvothermal and in situ etching methods, respectively. The impact of the mass ratio between two materials on the performance was assessed. The sensor based on 12 wt% Ti3C2Tx MXene/SnO2 composites demonstrates excellent performance in terms of sensitivity and response/recovery speed. Upon exposure to 50 ppm NH3, the frequency shift in the sensor is -1140 Hz, which is 5.6 times larger than that of pure Ti3C2Tx MXene and 2.8 times higher than that of SnO2 CQDs. The response/recovery time of the sensor for 10 ppm NH3 was 36/54 s, respectively. The sensor exhibited a theoretical detection limit of 73 ppb and good repeatability. Furthermore, a stable sensing performance can be maintained after 30 days. The enhanced sensor performance can be attributed to the abundant active sites provided by the accumulation/depletion layer in the Ti3C2Tx/SnO2 heterojunction, which facilitates the adsorption of oxygen molecules. This work promotes the gas sensing application of MXenes and provides a way to improve gas sensing performance.

Elucidating the hysteresis effect in printed flexible perovskite solar cells with SnO2 quantum dot- and PCBM-based electron transport layers

Recently, flexible perovskite solar cells (FPSCs) fabricated using solution-processed printing techniques have garnered significant attention. However, challenges remain in achieving cost-effective, scalable manufacturing under ambient conditions and ensuring stable, efficient devices. This study focuses on fabricating printed FPSCs using the slot-die coating technique and examines the impact of SnO2 quantum dot (QD) and (6,6)-Phenyl C61 butyric acid methyl ester (PCBM) based electron transport layers (ETLs) on device performance and hysteresis. Experimentally results show that SnO2 QD-based devices exhibited favorable photovoltaic properties but significant hysteresis compared to PCBM-based devices. Numerical simulations have shown that the hysteresis effect in devices is influenced not only by the higher concentration of mobile ions in the perovskite layer of PCBM-based devices compared to SnO2 QD-based devices, but also by the more effective redistribution of these ions during forward and reverse J-V scans. The results provide insights into the behavior of printed FPSCs with different ETLs, contributing to the development of high-performance, hysteresis-free printed FPSCs.

BiOBr/SnO2/ZnO Catalyst With Interfacial Effect Enhanced Photocatalytic Degradation of Organic Dye

ABSTRACTBiOBr nanosheets were loaded onto SnO2 quantum dots, ZnO nanosheets, and SnO2/ZnO‐2 (SZ‐2) to form different heterojunction photocatalysts by sonochemistry, respectively. The photocatalytic activity of the prepared photocatalysts was evaluated by degrading the target dye Rhodamine B (RhB). The results showed that the degradation efficiency of BiOBr/SnO2/ZnO (BSZ) for RhB reached 97.5% at 80 min. The significant increase in catalytic activity of BSZ was attributed to the synergistic and interfacial effects among the three materials. Combined with the radical trapping experiments, it can be concluded that the catalytic mechanism of BSZ as a dual Z‐type heterojunction.

Conformal SnO2 and NiOx charge transport layers for pragmatic air-processed perovskite solar cells

The industrialization of perovskite (PVK) solar cells (PSCs) necessitates simple manufacturing, cheapness, nontoxicity, high efficiency, and stability. We report an air-processed lead halide PSCs with cheap, nontoxic, stable NiOx and SnO2 as the hole and electron transport layers separately, to meet all the above commercial requests. By preparing the NiOx (water-dispersible) and SnO2 (oil-dispersible) quantum dots (QDs) with good conductivity and energy band matched well with that of PVK, we fabricate inverted PSCs (ITO/NiOx/PVK/SnO2/Ag) with efficiency up to 20.1/14.6% for active areas of 0.0707/1 cm2, under 1 sun simulated illumination with enhanced UV light ratio. The UV-light resistant PSCs reported here will impel their application in the high altitude areas with strong UV light. Importantly, the monodisperse size and dominant (110) plane of SnO2 QDs achieved by controlling the solvothermal parameters, realize the conformal deposition and defect prevention of SnO2, respectively, thus improving the PSC efficiency and stability.

Fullerene‐Free p–i–n Perovskite Solar Cells: Direct Deposition of Tin Oxide on Perovskite Layer Using Ligand Bridges

AbstractIn p–i–n perovskite solar cells (PSCs), fullerene derivatives are predominantly used as an electron transport material (ETM) despite their disadvantages, such as parasitic absorption in the short wavelength range and high cost. State‐of‐the‐art n‐i‐p PSCs are fabricated using SnO2 as the ETM due to their high charge transfer ability, transparency, and low cost. However, in p–i–n PSCs, dispersing SnO2 nanoparticles in a solvent that does not damage the perovskite and forming a uniform layer is challenging. Herein, a strategy of directly depositing SnO2 quantum dots (QDs) on perovskite using ethylenediamine (EDA) for high‐performance applications is reported, which involves a SnO2 QD solution designed with a damage‐free cosolvent. Treating the SnO2 QD layer with the EDA strategy creates a conformal SnO2 QD layer and improves charge transport. This strategy achieves a high power conversion efficiency (PCE) of 18.9% in PSCs with a 1.77 eV bandgap, which is the highest PCE reported for wide bandgap p–i–n PSCs using an inorganic ETM. The top SnO2 layer enables ITO deposition without sputtering damage and achieves a bifacial factor of 99% due to the high transmittance of SnO2 QD. The resulting four‐terminal all‐perovskite tandem exhibited a PCE of 27.0%.

Enhanced photocathodic protection performance of TiO2/SnO2/CdIn2S4 composites for 304 stainless steel in marine environments

In humid and saline environments, metal corrosion leads to significant economic losses, necessitating enhanced anti-corrosion methods. This study aims to enhance the photocathodic protection (PCP) performance of TiO2 nanotubes (NTs) by incorporating SnO2 quantum dots (QDs) and CdIn2S4 nanoflowers (NFs). TiO2 NTs were fabricated on titanium substrates via anodization, followed by successive deposition of SnO2 QDs and CdIn2S4 NFs using immersion and hydrothermal methods. The composite materials were characterized using SEM, TEM, XRD, and XPS. The PCP performance was evaluated through electrochemical tests on 304 stainless steel (304ss). The TiO2/SnO2/CdIn2S4 (T/S/C) composite exhibited a photocurrent density seven times that of pure TiO2 NTs, indicating significantly enhanced separation ability. The composite also demonstrated a notable open-circuit potential (OCP) of −1045 mV vs. SCE. Furthermore, T/S/C could provide delayed protection for up to 10 h in the dark, indicating its electron storage capability. The T/S/C composite material enhances the corrosion resistance of 304ss, offering a promising approach for practical anti-corrosion applications.

Electron transporting bilayers for perovskite solar cells: Spray coating deposition of c-TiO2/m-SnO2-quantum dots

Herein we present a comparative study among different spray-coated nanometric mesoporous electron transporting layers (ETLs) in perovskite solar cells (PSC), namely m-TiO2, m-SnO2 and m-SnO2 quantum dots (m-SnO2QDs). The solutions used for deposition were prepared from commercial pastes and colloidal suspensions for m-TiO2 and m-SnO2. For m-SnO2QDs in-house QDs solutions were prepared. The formamidinium-methylamonium-potassium (FAMA@10 K) has been used as light absorber material in the fabricated PSCs. The structural, compositional and morphological studies, correlated with the photovoltaic performance of PSCs, indicate that the m-SnO2 QDs layer is the best candidate among the three investigated mesoporous ETLs. Compared with the suspensions used for the other two ETLs, the in-house prepared SnO2 QDs solution presents smaller agglomerates of nanoparticles and results in the formation of a thinner, more uniform and compact mesoporous ETL. The FAMA@10 K perovskite deposited on m-SnO2 QDs ETL presents a lower roughness, better uniformity and a higher amount of PbI2. Our work unveils that the SnO2 QDs solution can be easily produced in laboratory and when is deposited as mesoporous scaffold in a PSC with FAMA@10 K perovskite, the power conversion efficiency increases up to 14.90 %, being with up to 27 % larger than in the PSCs with m-TiO2 and m-SnO2 ETLs prepared from commercial solutions. By modeling the J-V dynamic hysteresis with more than 90 % match between the calculated and experimental J-V data, for all three types of mesoporous ETLs, the relevant parameters that explain the hysteresis magnitude and account for ionic-induced recombination processes in PSCs were determined.

Boosted Electrochemical Activity with SnO2 Nanostructures Anchored on α-Fe2O3 for Improved Charge Transfer and Current Density

This study presents a straightforward and cost-effective method to enhance the photoelectrochemical (PEC) water-splitting performance of α-Fe2O3 (F), SnO2 (S), and α-Fe2O3 decorated with SnO2 quantum dots (FS) photoanodes in a NaOH electrolyte. The FS electrode demonstrated a notable improvement in PEC efficiency within the electrolyte. In particular, the generated charges of the FS anode in the NaOH electrolyte reached approximately 12.01 mA cm−2 under illumination, indicating that the developed heterostructures effectively enhanced kinetics, leading to improved separation of induced carrier pairs. This active carrier-pair separation mechanism contributed considerably to the increased PEC activity in the 0.1 M NaOH electrolyte. The reduction in the bandgap of FS increased its absorption capability in visible light, which further enhanced the current density. Furthermore, the reduction in electrolyte resistance (9.71 Ω), internal resistance (20.19 Ω), charge transfer resistance (3.21 kΩ), Tafel slope (45.5 mV dec-1), limiting current density (−2.09 mA cm−2), and exchange current density (−3.68 mA cm−2) under illumination at the interface enhanced the charge density of FS. Further, a strong interaction among photoanode nanostructures significantly enhances PEC activity by improving efficient charge separation and transport, reducing recombination rates, and enabling quicker movement of charge carriers to the electrode/electrolyte interface. Thus, this study provides an effective approach to increasing the PEC activity of heterostructures.

Synergistic integration of MoS2 nanopetals and SnO2 quantum dots for enhanced supercapacitor performance

This study presents the synthesis and electrochemical application of MoS2 nanopetals/SnO2 quantum dots (MS/SQD) nanocomposites. Employing a hydrothermal method for MoS2 and a simple mixing process for SnO2 using thiourea and tin chloride dihydrate, we engineered a nanocomposite that significantly enhances supercapacitor performance. Characterization through XRD, FE-SEM, FE-TEM, and XPS confirmed the optimal morphology and structural integrity of the MS/SQD. Electrochemical evaluations using a three-electrode system highlighted the nanocomposite’s exceptional electrochemical attributes: it achieved a specific capacitance of up to 505 F·g−1 at 1 A·g−1 and maintained 350 F·g−1 at a high current density of 10 A·g−1, with nearly 99% capacity retention after 5,000 cycles. The novelty lies in the synergistic effects of SnO2 quantum dots, which enhance the MoS2 nanopetal’s structural integrity, conductivity, and electrochemical reactivity, thereby improving charge transfer efficiency and ion diffusion. These findings underscore the MS/SQD nanocomposite’s potential for high-performance energy storage applications.

Nanoscale synergy: Optimizing energy storage with SnO2 quantum dots on ZnO hexagonal prisms for advanced supercapacitors

Abstract Electrode materials comprising SnO2 quantum dots embedded within ZnO hexagonal prisms were successfully synthesized for building cost-effective energy-storage devices. Extensive structural and functional characterizations were performed to assess the electrochemical performance of the electrodes. SEM–EDS results confirm a uniform distribution of SnO2 quantum dots across ZnO. The integration of SnO2 quantum dots with ZnO hexagonal prisms markedly improved the electrochemical behavior. The analysis of electrode functionality conducted in a 3 M KOH electrolyte revealed specific capacitances of 949.26 and 700.68 F g⁻1 for SnO2@ZnO and ZnO electrodes, respectively, under a current density of 2 A g⁻1. After undergoing 5,000 cycles at a current density of 15 A g⁻1, the SnO2@ZnO and ZnO electrodes displayed impressive cycling stability, maintaining specific capacitance retention rates of 89.9 and 92.2%, respectively. Additionally, a symmetric supercapacitor (SSC) device constructed using the SnO2@ZnO electrode showcased exceptional performance, exhibiting a specific capacitance of 83 F g⁻1 at 1.2 A g⁻1. Impressive power and energy densities were achieved by the device, with values reaching 2,808 and 70.2 W kg⁻1, respectively. Notably, the SnO2@ZnO SSC device maintained a capacity preservation of 75% throughout 5,000 galvanostatic charge–discharge sequences. The outcomes highlight the potential of SnO2@ZnO hexagonal prisms as candidates for energy-storage applications, offering scalability and cost-effectiveness. The proposed approach enhances the electrochemical performance while ensuring affordability, facilitating the creation of effective and financially feasible energy storage solutions.

Stepwise synthesis of magnetic mesoporous silica nanoparticles decorated with SnO2 quantum dots as an efficient, recyclable, and green nanocatalyst for the synthesis of benzo[a]pyrano[3,2‐c]phenazine derivatives

In this research, magnetic mesoporous silica nanoparticles decorated with SnO2 quantum dots (M‐MSNs/SnO2[QDs]) were successfully synthesized and characterized using several advanced techniques including FT‐IR, XRD, FE‐SEM, EDS, elemental mapping, VSM, and BET. This study demonstrates the synthesis of benzo[a]pyrano[3,2‐c]phenazine derivatives via a four‐component reaction between 2‐hydroxy‐1,4‐naphthoquinone, ortho‐phenylenediamine, malononitrile, and benzaldehyde derivatives in the presence of M‐MSNs/SnO2(QDs) in ethanol as a green solvent. The proposed catalyst efficiently catalyzed the synthesis of these compounds with yields of 87–96% in 70–100 minutes. The presented method offers a cost‐effective and environmentally friendly approach with numerous advantages, including high product yields, simple operation, short reaction times, low‐cost purification, and facile catalyst recovery.

G-C3N4 hollow tubes decorated with SnO2 quantum dots for photoelectrochemical applications

Graphitic carbon nitride (g-C3N4) has been widely used to improve photoelectrochemical (PEC) activity owing to its outstanding photoresponse and strength. In this study, g-C3N4 hollow tubes decorated with SnO2 quantum dots were prepared by combining hydrothermal and post-annealing approaches. In particular, different characterization techniques such as Fourier transform infrared, photoluminescence, ultraviolet–visible, and X-ray photoelectron spectroscopies were employed to investigate the electrical and optical behaviors of the samples. The prepared samples exhibited considerable photoresponse and excellent PEC performance, producing hydrogen. Furthermore, the heterostructures among SnO2 and g-C3N4 encouraged carrier separation, improving the PEC ability. In addition, the applied voltage showed numerous effects on generating charge carriers for the anodes in a 0.1 M sodium hydroxide electrolyte. Therefore, the proposed approach is simple and effective and can be used to enhance the performance of the PEC activity.

Dual Synapses and Security Devices from Ternary C60‐Pentacene‐TiO2‐x Nanorods Heterostructures

AbstractIn the context of information explosion, neuromorphic and hardware‐based security devices have garnered significant attention for their capacity to facilitate parallel computing and not be vulnerable to hacking, respectively. A demonstration of a dual photosynaptic (DPS) and physically unclonable function (PUF) devices characterized by ternary TiO2‐x nanorods (NRs)/Pentacene/C60 heterostructure are simultaneously presented. For the DPS device, the ternary heterostructure leads to parallel‐operating DPS characteristics: i) wavelength‐dependent (WD) synapse and ii) stimulus‐moment‐dependent (SMD) synapse. Each synaptic characteristic demonstrates a remarkable degree of plasticity, which signifies a smooth transition from short‐term potentiation (STP) to long‐term potentiation (LTP). Moreover, The face recognition assessments have unveiled recognition rates of 83.3% for 2 operational modes. Notably, the DPS device maintains stable performance on the business card, even after a rigorous 49‐day testing period and undergoing 1 000 bending cycles. Regarding the PUF device, the security keys with unique patterns are created due to random current distribution induced by placement‐dependent doping effects of SnO2 quantum dots (QDs). Moreover, near‐ideal inter‐hamming distances (inter‐HDs), uniformities, and entropies are verified for all cryptographic keys. These findings introduce a pioneering concept of photonic synapses with their successful integration onto various substrates, including the hardware‐based security PUF device.

Light-induced, room-temperature hydrogen gas detection based on SnO2 quantum Dots/p-Si

The continuous monitoring of the hydrogen gas level under low-temperature conditions is vital to prevent explosive accidents. Metal oxide-based chemoresistors have attracted significant attention owing to their excellent gas sensitivity. However, high operating temperature required to remove adsorbed oxygen species is still considered as an obstacle, limiting the application of the system. In addressing the temperature issue, this study introduced an approach in which a gas interaction layer was separated from the signal-sensing region. The proposed two-terminal device comprises a gas interaction layer of SnO2 quantum dots (QDs) and a p-doped silicon (p-Si) region characterized by high electronic conductivity and light sensitivity. Through visible light illumination, the recombination between gas interaction-induced electrons and photo-generated holes induces a change in output photocurrent, enabling room-temperature gas sensing without additional temperature control. Using this gas sensing scheme, the proposed sensor showed impressive gas detection performance in the low-temperature range, achieving a detection range of a few parts per million (ppm) in concentration (limit of detection range: 9.46–50 ppm).

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.

Highly efficient Z scheme heterojunction of colloidal SnO2 quantum dots grafted g-C3N4 for the degradation of rhodamine B under visible light

The strategic design of the heterojunction photocatalyst with an enhancement in the charge transfer rate of photogenerated charge carriers plays a key role in wastewater treatment to remove organic pollutants. In the current study, the heterojunction of g-C3N4/SnO2 quantum dots (g-CN/c-SQDs) with different ratios of SQDs was prepared via sonochemical route. The Z scheme for the photocatalyst of g-CN/c-SQDs in visible light exhibits an exceptional degradation performance of RhB dye (98.25 % in 40 min) with cyclic stability. The enhancement of photocatalytic degradation efficiency is ascribed to efficient charge transfer and redox reactions due to the design of the heterojunction between high surface areas of g-C3N4 and c-SQD, which is evident from the results from photoluminescence spectra and scavenger experiments. The free radical capture experiments reveal the electron transfer pathway and the generation of reactive oxygen species (ROS) generation, including superoxide (•O2–) and hydroxyl (•OH) radicals has been involved in the photocatalytic degradation process. This study provides an insight of the construction of the Z- scheme heterojunction with an appropriate amount of semiconductor for an enhancement of photodegradation efficiency in wastewater treatment.

Vacancy-Rich SnO2 Quantum Dot Stabilized by Polyoxomolybdate as Electrocatalyst for Selective NH3 Production.

The pronounced conductivity of tin dioxide (SnO2) nanoparticles makes it an ideal multifunctional electrode material, while the challenge is to stabilize the quantum dot (QD) SnO2 nanocore in water. An Anderson-type polyoxomolybdate, (NH4)6[Mo7O24], is employed as an inorganic ligand to stabilize a ca. 6 nm SnO2 QD (Mox@SnO2). X-ray scattering and diffraction studies confirm the tetragonal SnO2 nanocore in Mox@SnO2. Elemental analyses are in good agreement with the mass spectrometric detection of the [Mo7O24]6- cluster present in Mox@SnO2. The ionic POMs attached to the SnO2 surface through [Mo-O-Sn] covalent linkages have been established by surface zeta potential, shift of the [Mo = O]t Raman vibration, and extended X-ray absorption fine structure (EXAFS) analyses. The presence of the [Mo7O24]6- cluster in the Mox@SnO2 is responsible for the remarkable aqueous stability of Mox@SnO2 in the pH range of 3-9. Dominant oxygen vacancy in the SnO2 core, identified by EXAFS data and the anisotropic electron paramagnetic resonance (EPR) signals (g ∼ 2.4 and 1.9), results in facile electronic conduction in Mox@SnO2 while being deposited on the electrode surface. Mox@SnO2 acts as an active catalyst for the electrocatalytic nitrate reduction (eNOR) to ammonia with 94% faradaic efficiency (FE) at -0.2 V vs RHE and a yield rate of 28.9 mg h-1 cm-2. The stability of Mox@SnO2 in acidic pH provides scope to reuse the Mox@SnO2 electrode at least four times with notable NH3 selectivity and a superior production rate (239.06 mmol g-1(cat) h-1). This study demonstrates the essential role of POM in stabilizing SnO2 QD, harnessing its electrochemical activity toward electrocatalytic ammonia production.

Bio-ultrasonic synthesis of tin oxide quantum dots: effect of bio-carbon and their UV photocatalytic activity

An ecofriendly synthesis is realized to elaborate tin oxide quantum dots (SnO2 -QDs) using the plant aqueous extract of Aloe Barbadensis Miller (Aloe Vera) and SnCl4.5H2O at room temperature as a biological solvent and a precursor respectively. The effect of Aloe Vera extract concentration on the properties of SnO2-QDs has been studied. Morphological and structural properties of the as synthesized nanoparticles have been characterized using field effect-scanning electron microscopy (FE-SEM) and x-ray diffraction (XRD). The chemical composition of the nanoparticles was studied by Raman, energy dispersive x-ray (EDX) and Fourier transformation infra-red (FTIR) spectroscopy. The optical properties were investigated by UV–Vis spectrophotometer. The x-ray diffraction analysis showed that all samples have a tetragonal rutile structure, with an estimated crystal size closed to the exciton Bohr radius, indicating a strong confinement of the carriers in the material. The crystallite size of SnO2-QDs nanoparticles decreases as Aloe Vera plant extract concentration increases. The formation of SnO2-QDs and the presence of graphitic carbon in samples were confirmed by Raman spectroscopy, EDX analysis and Fourier transformation infra-red (FTIR) spectroscopy. The blue shift in absorption is the most likely due to the quantum confinement effect. An Ostwald-repining growth model based on the concept of surface energy has been proposed to explain the kinetic growth of SnO2 QDs. The photocatalytic activities of the as-prepared powders were confirmed by the fast and efficient degradation of methylene blue (MB).

Mesoporous SnO2-modified electrode for electrochemical detection of luteolin

Conventional methods like chromatography and spectroscopic analysis have limitations in detecting luteolin. However, electrochemical detection shows promise for reliable analysis. In this study, we compared two different morphologies of SnO2 with the same crystal structure for luteolin detection and found that crystal morphology significantly impacts the catalytic reaction. Compared to SnO2 quantum dots (SnO2 QDs), mesoporous SnO2 (m-SnO2) exhibited a larger specific surface area, providing more active sites for oxidation and reduction reactions. Moreover, m-SnO2 had lower impedance, effectively accelerating charge transfer at the electrode surface. Based on these excellent characteristics, m-SnO2/GCE modified electrode demonstrated outstanding performance in detecting luteolin, achieving a sensitivity of 8.5 μA μM-1, a low limit of 0.19 nM and a wide linear range from 0.5 nM to 1,400 nM. Besides, the m-SnO2/GC electrode displayed excellent consistency, reproducibility, durability, repeatability and specificity. Even three-week exposure to atmospheric conditions, the DPV signal stood at 94.1 % of its original peak current. Those enables its excellent application in practical sample detection. This research enhances our understanding of the influence of material structure and interface on catalytic luteolin detection, providing a theoretical foundation for accurate detection in complex systems. These findings should contribute to the development of more efficient, sensitive, and reliable luteolin sensors.

Interface engineered cascade-type electronic structure of 2D/0D/2D CdS–CdCO3/SnO2 quantum dots/g-C3N4 nanocomposite for boosting solar-driven photocatalysis

A rational design of heterojunctions with high-quality contacts is essential for efficiently separating photogenerated charge carries and boosting the solar-driven harvesting capability. Herein, we fabricated a novel heterojunction of SnO2 quantum dots–anchored CdS–CdCO3 with g-C3N4 nanosheets as a superior photocatalyst. SnO2 quantum dots (SQDs) with positively charged surfaces were tightly anchored on the negatively charged surface of CdS nanosheets (NSs). The resulting CdS@SnO2 was finally decorated with g-C3N4 NSs, and a new crystalline phase of CdS–CdCO3 was formed during the hydrothermal decoration process, g-C3N4 decorated CdS–CdCO3@SnO2 (CdS–CdCO3@SnO2@g-C3N4). The as-synthesized photocatalysts were evaluated for the degradation of methyl orange dye under solar light conditions. The CdS–CdCO3@SnO2@g-C3N4 exhibited 7.7-fold and 2.3-fold enhancements in photocatalytic activities in comparison to those of the bare CdS and CdS@SnO2 NSs, respectively. The optimal performance of CdS–CdCO3@SnO2@g-C3N4 is primarily attributed to the cascade-type conduction band alignments between 2D/0D/2D heterojunctions, which can harvest maximum solar light and effectively separate photoexcited charge carriers. This work provides a new inspiration for the rational design of 2D/0D/2D heterojunction photocatalyst for green energy generation and environmental remediation applications.