Effect of Zn dopant on SnO2 nano-pyramids for photocatalytic degradation

The influence of Sn particle incorporation on the photocatalytic activity of sprayed ZnO-SnO2 nanocomposites

This paper investigates the photocatalytic performance of ZnO-SnO2 nanocomposites deposited using the Spray Pyrolysis technique, with varying percentages of tin oxide (20, 60, and 80%) on glass substrates at 350 °C. Comprehensive characterization of the samples was carried out using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), and UV-Vis spectroscopy to analyze their structural, morphological, and optical properties. The XRD analysis confirmed the hexagonal structure of zinc oxide and the tetragonal phase of tin oxide in the nanocomposites. The average crystallite size was found to decrease with an increase in the percentage of tin oxide. The UV-Vis spectra demonstrated that the band gap energy of the ZnO-SnO2 nanocomposite increased from 3.29 to 3.64 eV as the amount of Sn increased. The Urbach energy decreases reflecting an improvement in the structural and electronic quality of the material, with fewer defects and better crystallinity. Additionally, The SEM results reveal a transition in surface morphology with increasing Sn content, shifting from a smooth, compact structure to a highly aggregated particle surface, with the highest thickness (740 nm) observed at 80% SnO2. Remarkably, the ZnO-SnO2 nanocomposite with 80% tin exhibited superior photocatalytic activity, successfully degrading 91% of methylene blue solution within 180 min under UV irradiation. Moreover, the stability and reusability of the sample were demonstrated through repeated photocatalytic cycles. The use of a chemical synthesis technique for the elaboration of the Sn:Zn mixed nanocomposite and UV light as catalyzer which, is well suited for large bandgap materials, optimizes this work by providing an increased contact surface area and facilitating the interaction between the photocatalyst and the target molecules. These findings highlight its potential for effective environmental applications, specifically in photocatalysis for pollution control and environmental protection. The results collectively suggest that ZnO-SnO2 nanocomposites, deposited through the spray method, represent promising candidates for advancing photocatalytic technologies.

Cl2 gas properties, temperature, and humidity effects on SnO2 sensor response: transition state theory study

CONTEXT

Chlorine properties that affect its reaction with the SnO2 sensor surface are discussed. This includes temperature variation and Cl2 reaction with humidity. Transition state theory formalism evaluates related thermodynamic properties such as Gibbs free energy and its components, enthalpy, and entropy. Logistic functions determine the effective concentration of Cl2 gas due to its reaction with humidity and sensor material. The Gibbs free energy of adsorption and transition or activation is evaluated as a function of temperature. Results include SnO2 sensor response to Cl2 gas as a function of temperature and Cl2 concentration. Results also include response time and the effect of humidity. An optimum response temperature can be between room temperature and 200 °C. A comparison with available experimental results is performed, which shows a good agreement between theory and experiment. The present model is the only available model that can successfully compare the theory and experiment of response and response time, including temperature and humidity effects.

METHODS

Gaussian 09 software package is used with B3LYP level of DFT since most previous successful gas sensor calculations are performed using this version of DFT. 6-311G** basis sets are used to represent oxygen and chlorine atoms, while SDD functionals are used to represent heavier Sn atoms.

Direct Redox Sensing of Caffeine Utilizing Zinc-Doped Tin Oxide Nanoparticles as an Electrocatalyst

Objective: In addition to its positive benefits, caffeine also has harmful consequences. Therefore, it is essential to ascertain its content in various substances. Impact Statement: The present study emphasizes a novel way of quantification of caffeine in real as well as laboratory samples based on a nanomaterial-assisted electrochemical technique. Introduction: Electrochemical sensing is a prominent analytical technique because of its efficiency, speed, and simple preparation and observations. Due to its low chemical potential, SnO2 (tin oxide) demonstrates rapid redox reactions when used as an electrode. The presence of shielded 4f levels contributes to its distinctive optical, catalytic, and electrochemical capabilities. Methods: An efficient coprecipitation approach, which is simple and rapid and operates at low temperatures, is utilized to produce zinc-doped tin oxide nanoparticles (Zn-SnO2 nanoparticles). Zinc doping is used to modify the optoelectronic characteristics of tin oxide nanoparticles, rendering them very efficient as electrochemical sensors. Results: The crystal structure of samples was analyzed using x-ray diffraction, electronic transitions were calculated using ultraviolet-visible spectroscopy, and surface morphology was analyzed using field emission scanning electron microscopy. The x-ray diffraction investigation revealed that the produced Zn-doped SnO2 nanoparticles exhibit tetragonal phases, and the average size of their crystallites reduces upon doping Zn with SnO2. The bandgap energy calculated using the Tauc plot was found to be 3.77 eV. Conclusion: The fabricated caffeine sensor exhibits a sensitivity of 0.605 μA μM -1 cm-2, and its limit of detection was found to be 3 μM.

Visible light activated SnO2:Dy thin films for the photocatalytic degradation of methylene blue

This paper explores the impact of dysprosium (Dy) doping on structural, optical, and photocatalytic properties of tin oxide (SnO2) thin films fabricated via spray pyrolysis. Dysprosium doping levels ranged from 0 to 7 at%, and films were grown on glass substrates at 350 °C. X-ray diffraction (XRD) analysis revealed an increase in crystallite size with Dy doping, signifying improved crystalline quality. Simultaneously, dislocation density and strain decreased, indicating enhanced film quality. Texture coefficient (Tchkl) results showed a predominant crystal orientation along the (110) plane due to Dy doping. Optical band gap energy (Eg) decreased with Dy doping up to 5%. Urbach energy increased with Dy doping, suggesting atomic structural flaws and defects. Scanning electron microscopy (SEM) analysis revealed the presence of numerous micro-aggregates on the film's surface. Notably, the density of these micro-aggregates increased proportionally with higher Dy doping levels, particularly emphasizing the pronounced effect observed in SnO2:Dy 5% thin films. These findings underscore the potential of Dy-doped SnO2 thin films for advanced photocatalytic applications, with SnO2:Dy 5% exhibiting favorable properties and demonstrating a 90.99% degradation efficiency in three hours under solar irradiation.

Green Derived Zinc Oxide (ZnO) for the Degradation of Dyes from Wastewater and Their Antimicrobial Activity: A Review

The quest for eco-friendly synthetic routes that can be used for the development of multifunctional materials, in particular for water treatment, has reinforced the use of plant extracts as replacement solvents in their use as reducing and capping agents during the synthesis of green derived materials. Amongst the various nanoparticles, Zinc Oxide (ZnO) has emerged as one of the preferred candidates for photocatalysis due to its optical properties. Moreover, ZnO has also been reported to possess antimicrobial properties against various bacterial strains such as E. coli and S. aureus. In this review, various types of pollutants including organic dyes and natural pollutants are discussed. The treatment methods that are used to purify wastewater with their limitations are highlighted. The distinguishing properties of ZnO are clearly outlined and defined, not to mention the performance of ZnO as a green derived photocatalyst and an antimicrobial agent, as well. Lastly, an overview is given of the challenges and possible further perspectives.

Photocatalytic Conversion of Fructose to Lactic Acid by BiOBr/Zn@SnO2 Material

Photocatalysis provides a prospective approach for achieving high-value products under mild conditions. To realize this, constructing a selective, low-cost and environmentally friendly photocatalyst is the most critical factor. In this study, BiOBr/Zn@SnO2 is fabricated by a one-pot hydrothermal synthesis method and BiOBr: SnO2 ratio is 3:1; this material is applied as photocatalyst in fructose selective conversion to lactic acid. The bandgap structure can be regulated via two-step modification, which includes Zn doping SnO2 and Zn@SnO2 coupling BiOBr. The photocatalyst shows excellent conversion efficiency in fructose and high selectivity in lactic acid generation under alkaline conditions. The conversion rate is almost 100%, and the lactic acid yield is 79.6% under optimal reaction conditions. The catalyst is highly sustainable in reusability; the lactic acid yield can reach 67.4% after five runs. The possible reaction mechanism is also proposed to disclose the photocatalysis processes.