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In the field of synthesis and processing of noble metal nanoparticles, the study of the bottom-up method, called Ultrasonic Spray Pyrolysis (USP), is becoming increasingly important. This review analyses briefly the features of USP, to underline the physical, chemical and technological characteristics for producing nanoparticles and nanoparticle composites with Au and Ag. The main aim is to understand USP parameters, which are responsible for nanoparticle formation. There are two nanoparticle formation mechanisms in USP: Droplet-To-Particle (DTP) and Gas-To-Particle (GTP). This review shows how the USP process is able to produce Au, Ag/TiO2, Au/TiO2, Au/Fe2O3 and Ag/(Y0.95 Eu0.05)2O3 nanoparticles, and presents the mechanisms of formation for a particular type of nanoparticle. Namely, the presented Au and Ag nanoparticles are intended for use in nanomedicine, sensing applications, electrochemical devices and catalysis, in order to benefit from their properties, which cannot be achieved with identical bulk materials. The development of new noble metal nanoparticles with USP is a constant goal in Nanotechnology, with the objective to obtain increasingly predictable final properties of nanoparticles.

The present study reports on the effect of substrate temperature on structural, morphological and optical properties of MoO 3 thin films. MoO 3 thin films were deposited on pre-heated glass substrate using spray pyrolysis technique. The substrate temperature was varied from 300 °C to 400°C with a step interval of 50 °C. Structural studies were studied using X-ray diffraction technique. It is observed that all the diffraction peaks exactly match with JCPDS card No. 05-0508. The as –deposited MoO 3 thin films exhibits orthorhombic crystal structure. It is found that the crystalline nature increases with the increases of substrate temperature. FESEM micrographs show that the grains are distributed uniformly over the surface without any void. An optical property reveals that the transmission of MoO 3 thin film in the visible region increases with increases of deposition temperature.

In the current work, the effect of zinc doping on the structural and optical properties of iron oxide has been explored for optoelectronic applications. Undoped and different (2–10 wt%) Zn-doped iron oxide (Fe 2 O 3 /Zn) nanostructured films (nFs) were successfully prepared via spray pyrolysis technique. The structural, morphological, bonds vibrations and optical properties of the prepared films were examined using X-ray diffraction (XRD), scanning electron microscope (SEM), FT-IR and UV-Vis-NIR spectroscopy techniques, respectively. The XRD measurements reveal the formation of the rhombohedral hematite phase structure of iron oxide (α-Fe 2 O 3 ) for all prepared films. The FT-IR spectra analysis exhibits the existence of absorption bands corresponded to the stretching and bending vibrations of Fe–O and O–Fe–O bonds, respectively. The UV–Vis–NIR measurements of the prepared samples indicate the significant effect of Zn doping on various optical properties of Fe 2 O 3 films. The achieved optical bandgap of Fe 2 O 3 /Zn nFs is tuned from 2.38 eV (undoped Fe 2 O 3 ) to 2.83 eV (10 wt% of Fe 2 O 3 /Zn). These findings are explained on the basis of the created localized energy levels and Burstein–Moss effect. As a novel result of this study, Fe 2 O 3 /Zn nFs are well-qualified for the use in modern optoelectronic applications.

In this present work, we have studied the effect of organic solvents and acetylacetone (Acac) molar ratio on several properties of TiO 2 thin films prepared by pneumatic spray pyrolysis (SP). The TiO 2 thin films were characterized by the following techniques including the following: X-ray diffraction (XRD), Raman spectroscopy, Scanning Electron Microscopy (SEM) and UV–visible spectrophotometer. The XRD results showed pure anatase TiO 2 thin films with preferential orientation (101) plan, the crystallite size varying between 14.72 and 35.12 nm. The Raman spectroscopy confirmed the formation of the only phase of TiO 2 (anatase). The morphological properties were investigated by SEM. The UV–Visible spectrophotometer showed the semiconducting properties of anatase TiO 2 , and the optical band gap was ranged between 3.17–3.34 eV. The refraction index, the extinction coefficient and the porosity were estimated using transmittance values. The TiO 2 thin films have had good properties. They were prepared by low-cost technique, spray pyrolysis, by saving energy and time because the samples were synthesized using air pulverization without using any oxygen sources and without any annealing requires the following: CVD room, low pressure and more time for annealing (Sahoo et al. 2019 in Phys Chem Chem Phys 21: 6198–6206).

Among all the transition metal oxides, iron oxide-based materials are excellent for supercapacitor performance. Here, Mn-incorporated α-Fe2O3 (Mn:α-Fe2O3) nanostructured thin films (with 3%, 5%, and 7% Mn) are prepared via spray pyrolysis. All the synthesized nanostructured thin films are characterized by x-ray diffraction (XRD), optical study, Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and contact angle for the structural, optical, morphological and wettability analysis, respectively. The band gap of Mn:α-Fe2O3 nanostructured thin films is tuned by changing Mn concentration. The increasing Mn concentration shifts the valance band edge towards the conduction band edge, reducing the band gap. The linear band gap decrease of 0.44 eV with the addition of Mn concentration, along with the band gap reduction, affects supercapacitive performance. The prepared 7% Mn:α-Fe2O3 nanostructured electrode exhibits excellent specific capacitance of 688.6 F g−1 at a scan rate of 5 mV s−1 in 1 M Na2SO4 electrolyte, energy density (6 Wh kg−1), and power density (12 kW kg−1) at a current density of 5 mA g−1.

This study presents findings related to the characterization of cubic SnS (π-SnS) thin films and p-SnS/n-Si heterojunction structures produced simultaneously using the ultrasonic spray pyrolysis technique. In this context, the impact of different spray solution flow rates on the morphological, structural, optical, and electrical characteristics of the films was examined. Morphological analyses revealed that higher flow rates resulted in films with denser and smoother surfaces, approximately 6 nm in roughness. Additionally, it was observed that both the thickness and the growth rate of the films could be adjusted through the modulation of the flow rate. Structural analyses determined that the crystallite size increased and micro-strain values decreased with increasing flow rates. Optical evaluations indicated a decline in the optical band gap of the thin films from about 1.8 eV to 1.7 eV as the flow rates increased. This trend was consistently observed in the data obtained using the Tauc method and the derivative of transmission with respect to wavelength versus photon energy graphs. Electrical analyses revealed that the resistivity values of the thin films increased from 5.24 × 10 5 Ωcm to 1.64 × 10 6 Ωcm with increasing flow rates. Furthermore, I-V analyses of the Au/p-SnS/n-Si/Ag heterojunction structures indicated significant variability in key electrical properties. The saturation currents displayed a broad range, suggesting varying efficiencies in charge carrier collection across different samples. Similarly, the change of ideality factors pointed to differences in charge transport mechanisms, while the shifts in barrier heights indicated changes in junction properties with different fabrication conditions. The results of this study offer valuable perspectives for future research.

Submicron and nanosized powders have gained significant attention in recent decades due to their broad applicability in various fields. This work focuses on ultrasonic spray pyrolysis, an efficient and flexible method that employs an aerosol process to synthesize titanium-based nanoparticles by transforming titanium oxy-sulfate. Various parameters are monitored to better optimize the process and obtain better results. Taking that into account, the influence of temperature on the transformation of titanium oxy-sulfate was monitored between 700 and 1000 °C. In addition to the temperature, the concentration of the starting solution was also changed, and the flow of hydrogen and argon was studied. The obtained titanium-based powders had spherical morphology with different particle sizes, from nanometer to submicron, depending on the influence of reaction parameters. The control of the oxygen content during synthesis is significant in determining the structure of the final powder.

HighlightsIndustrially viable bottom-up spray pyrolysis deposition technique was used to prepare the highly compact TiO2 film, which is a vital element for the multi-layer front contact.The optimization of the front contact is presented by fabricating reproducible and efficient perovskite solar cellsMulti-layer front contact is applied to realize efficient perovskite single-junction and perovskite/perovskite tandem solar cells, where optics and electrical effects of solar cells are studied by optically coupled 3D electromagnetic simulations.The photovoltaic performance of perovskite solar cells (PSCs) can be improved by utilizing efficient front contact. However, it has always been a significant challenge for fabricating high-quality, scalable, controllable, and cost-effective front contact. This study proposes a realistic multi-layer front contact design to realize efficient single-junction PSCs and perovskite/perovskite tandem solar cells (TSCs). As a critical part of the front contact, we prepared a highly compact titanium oxide (TiO2) film by industrially viable Spray Pyrolysis Deposition (SPD), which acts as a potential electron transport layer (ETL) for the fabrication of PSCs. Optimization and reproducibility of the TiO2 ETL were discreetly investigated while fabricating a set of planar PSCs. As the front contact has a significant influence on the optoelectronic properties of PSCs, hence, we investigated the optics and electrical effects of PSCs by three-dimensional (3D) finite-difference time-domain (FDTD) and finite element method (FEM) rigorous simulations. The investigation allows us to compare experimental results with the outcome from simulations. Furthermore, an optimized single-junction PSC is designed to enhance the energy conversion efficiency (ECE) by > 30% compared to the planar reference PSC. Finally, the study has been progressed to the realization of all-perovskite TSC that can reach the ECE, exceeding 30%. Detailed guidance for the completion of high-performance PSCs is provided.

In this study, the effects of silver (Ag) doping on the structural, morphological, optical, and electrical properties of tin monosulfide (SnS) thin films were investigated. The films, undoped and doped with 3%, 6%, and 9% Ag, were deposited using the ultrasonic spray pyrolysis (USP) technique at a substrate temperature of 350 °C. X-ray diffraction (XRD) analysis confirmed a π -SnS (cubic) structure with (400) preferred orientation for undoped and ≤ 6% Ag-doped films, while 9% doping induced amorphization due to severe lattice distortions. Morphological analyses revealed smooth, void-free surfaces, with average roughness increasing from 5.8 nm (undoped) to 19.6 nm (9% doping). Optical measurements showed that the band gap widened from 1.84 eV (undoped) to 2.47 eV (9% Ag-doped), and Urbach energy increased from 190 meV to 600 meV. Hall effect measurements confirmed p-type conductivity for all films. Resistivity ranged from 4.34 × 10 5 Ωcm to 9.48 × 10 5  Ωcm, carrier concentration varied between 2.7 × 10 12  cm -3 and 5.6 × 10 12  cm -3 , while mobility decreased from 3.3 × 10 1  cm 2 /Vs to 2.0 × 10 1  cm 2 /Vs with increasing Ag doping. These findings demonstrate that Ag doping significantly influences the structural and optoelectronic behavior of SnS thin films, making them promising candidates for thin-film solar cells and optoelectronic applications. Graphical Abstract Highlights Ag doping narrows crystallite size; 9% doping results in amorphous SnS films. Optical band gap widens from 1.83 eV to 2.47 eV with increased Ag doping. SEM/AFM reveal nearly void-free surfaces; roughness increases with Ag doping. High Urbach energy signals increased electronic disorder with higher Ag doping. Ag doping optimizes SnS films for photovoltaic and optoelectronic applications.

For industrial processes—like waste incineration—it is necessary to reduce solid components (like dust or fly ash) as well as gaseous components (like dioxins, CO and other harmful hydrocarbons) to fulfill legal requirements. Therefore, catalytically functionalized filters based on polymers already exist. However, it is known that such filters are always constructed in multiple layers to prevent the migration of catalyst particles. This study demonstrates that it is possible to prepare a stable catalytic functionalized single-layer filter based on polyester needle felt by using flame spray pyrolysis. The catalyst is a low temperature active Pt/TiO 2 with a loading weight of 38 g/l on the filter. Via SEM images the uniform distribution of the catalytic particles even in the deeper regions of the single-layer filter was proven. The structure was confirmed after experiments under realistic conditions—migration could not be obtained. Likewise, it was obtained that the oxidative conversion of carbon monoxide (CO) to carbon dioxide (CO 2 ) is completely even at temperatures below 100 °C. Furthermore, comparative studies with catalysts on a honeycomb and a ceramic foam have shown that the conversion on the polyester needle felt textile catalyst is comparable.