Flame spray pyrolysis synthesis and aerosol deposition of nanoparticle films

Abstract

The assembly of nanoparticle films by flame spray pyrolysis (FSP) synthesis and deposition on temperature‐controlled substrates (323–723 K) was investigated for several application‐relevant conditions. An exemplary SnO2 nanoparticle aerosol was generated by FSP and its properties (e.g., particle size distribution), and deposition dynamics were studied in details aiming to a simple correlation between process settings and film growth rate. At high precursor concentrations (0.05–0.5·mol/L), typically used for FSP synthesis, the nanoparticles agglomerated rapidly in the aerosol leading to large (>100 nm) fractal‐like structures with low diffusivity. As a result, thermophoresis was confirmed as the dominant nanoparticle deposition mechanism down to small (≈40 K) temperature differences (ΔT) between the aerosol and the substrate surface. For moderate‐high ΔT (>120 K), thermal equilibrium was rapidly obtained yielding a constant thermophoretic flux and film growth rate. A model was developed to predict the nanoparticle deposition rates by FSP synthesis at moderate‐high ΔT that does not require detailed analysis of the aerosol composition. Comparison with previous studies having similar nozzle geometries showed that the deposition rates of FSP‐made aerosols can be reasonably well predicted for various materials and flame conditions. © 2012 American Institute of Chemical Engineers AIChE J, 2012

High‐Temperature One‐Step Synthesis of Efficient Nanostructured Bismuth Vanadate Photoanodes for Water Oxidation

“…Furthermore, here, a linear correlation was determined between the deposition time and the film absorbance (Figure d). This indicates a constant BiVO 4 mass deposition rate at each HAB in line with previous modeling of the aerosol deposition process . Moreover, the film thickness increased also linearly with the deposition time indicating that a constant porosity is obtained at each HAB (Figure S2 and S3, Table S1, Supporting Information).…”

“…Very recently, direct deposition of flame‐made nanoparticle aerosols has been used to produce mechanically stable hierarchical electrodes for ZnO‐based dye‐sensitized solar cells and efficient WO 3 photoanodes . This high‐temperature self‐assembly approach could also potentially provide a solution to apply a more favorable temperature profile for the synthesis of BiVO 4, besides being a well‐established route for the mass production of numerous nanoparticle commodities such as carbon black, fumed silica, and Degussa P25.…”

“…This allows for a direct control of the specific surface area of the sample and hence on the amount of active sites that promote the reactions. Decreasing HAB from 15 to 6 cm increases the surface temperature from 600 to 800 C. Taking advantage of the constant nanoparticle flux depositing from the aerosol, [23] the mass loading and optical density of the films were linearly controlled by the deposition time, enabling the fabrication of well-controlled morphologies. To remove any surface impurities adsorbed during the flame synthesis, all films were calcined in air at 450 C after deposition.…”

Low-cost photo-responsive nanocarriers by one-step functionalization of flame-made titania agglomerates withl-Lysine

“…2b), the agglomerates were iden-tied as clusters of TiO 2 primary particles with a size between 5 and 50 nm. 38 Most importantly, the TiO 2 agglomerate size obtained here is sufficiently large (>50 nm) to maximize circulation time for drug delivery, avoiding both renal ltration and vascular fenestration, while their elongated chain-like morphology (Fig. Here, dynamic light scattering analysis showed a unimodal particle size distribution with a hydrodynamic diameter (d H ) of 180 nm and a quasi-lognormal shape (s g ¼ 1.306).…”

“…1a). 38 The XRD analysis (ESI, Fig. 23 A high precursor concentration (0.5 mol l À1 ) and feed rate (5 ml min À1 ) were used to ensure the scalability of the nanocarrier synthesis process and structural properties.…”