Natural light harvesting organisms have evolved to harvest sunlight efficiently. Green sulfur bacteria, which contain chlorosomes, can survive in extremely low light conditions mainly because of efficient light absorption and transfer of energy, facilitated by the assembled dye molecules. Due to these reasons, chlorosomes have been used in dye sensitized solar cells to improve the light absorption and performance. The chlorosome absorption spectrum is fixed and their size is dependent on the organism. Various solution-based techniques have been developed for synthesizing mimics by supramolecular self-assembly. However, controlling the size of agglomerates and their subsequent deposition on surfaces to fabricate a device is difficult. In this work, a one-step aerosol-based self-assembly technique has been developed for the first time, to assemble and deposit chlorin (Bacteria chlorophyll mimics) agglomerates. A shift in absorption spectra of 79 nm which is comparable to the natural system was obtained. The analysis shows that kinetics of nucleation play an important role in assembly.

Highly efficient Pt-TiO2 composite photoelectrodes were synthesized by combining two novel deposition methods: ACVD and a room temperature RF (radio frequency) magnetron sputtering method. A room temperature RF magnetron sputtering method allowed uniform deposition of Pt nanoparticles (NPs) onto the as-synthesized nanostructured columnar TiO2 films by ACVD. Pt NP sizes from 0.5 to 3 nm demonstrating a high particle density (>1012 cm−2) could be achieved by varying deposition time with constant pressure and power intensity. As-synthesized Pt-TiO2 films were used as photoanodes for water photolysis. Pt nanoparticles deposited onto the TiO2 film for 20s produced the highest photocurrent (7.92 mA/cm2 to 9.49 mA/cm2) and maximized the energy conversion efficiency (16.2 % to 21.2 %) under UV illumination. However, as the size of Pt particles increased, more trapping sites for photogenerated electron-hole pairs decreased photoreaction.

All photosynthetic organisms contain light-harvesting antenna complexes and electron transfer complexes called reaction centers. Some photosynthetic bacteria contain large (~100 MDa) peripheral antenna complexes known as chlorosomes. Chlorosomes lose their reaction center when they are extracted from organisms. Lead sulfide (PbS) quantum dots (QDs) were used for artificial reaction centers. Successive ionic layer adsorption and reaction (SILAR) allows different sizes of PbS QDs with different cycles to be easily deposited onto the nanostructured columnar titanium dioxide (TiO2) film with single crystal. Chlorosomes were sequentially deposited onto the PbS QDs surface by electrospray. Compared to the typical PbS QD sensitized solar cells, overall energy conversion efficiency increased with the Förster resonance energy transfer (FRET) effect between PbS QDs and chlorosomes.

A single step gas phase method was developed to synthesize silica-coated iron oxide nanocomposite materials in a furnace aerosol reactor (FuAR) using premixed precursors. Synthesis of single component silica and magnetic iron oxide was studied to understand the decomposition mechanism of the precursors, identify the product crystal phase, and optimize the viable operating conditions for the controlled synthesis of nanocomposite material with desirable crystal phase, size, and morphology. The single component decomposition results are further extended to synthesize silica-coated magnetic iron oxide nanocomposite material using premixed precursor. A mechanism was proposed to explain the formation of SiO2-coated γ-Fe2O3 nanocomposite in a single step in a FuAR based on chemical kinetics and was verified by supporting characterization results. The synthesized magnetic γ-Fe2O3/SiO2 nanocomposite material was further tested for suspension stability, magnetic properties, and surface reactivity and was compared with uncoated γ-Fe2O3 nanoparticles to demonstrate improved surface properties.

A discrete-sectional model accounting for particle formation by chemical reaction and growth by coagulation and condensation is developed to predict the evolution of the nanocomposite aerosol size distribution in a multicomponent iron-silicon system in a flame. Particle formation by nucleation of the vapor is represented by an Arrhenius-type rate expression, with the rate constant being obtained from experiments and simulation results reported in the literature. Precursor vapor concentrations and the second aerosol volume moment predictions are compared to laser-induced fluorescence (LIF) and light scattering intensity measurements from experiments described in Part I20 of the paper. The results elucidate the important formation and growth mechanisms of nanocomposite ferric oxide-silica particles in flame reactors. The role of operating parameters such as precursor characteristics and temperature profiles on the final product characteristics is established.

Planar laser-based imaging measurements of fluorescence and particle scattering have been obtained during flame synthesis of iron-oxide/silica superparamagnetic nanocomposites. The theory and application of laser-induced fluorescence, the spectroscopy of FeO(g), and the experimental approach for measurement of gas phase precursors to particle formation are discussed. The results show that the vapor phase FeO concentration rapidly rises at the primary reaction front of the flame and is very sensitive to the amount of precursor added, suggesting nucleation-controlled particle growth. The FeO vapor concentration in the main nucleation zone was found to be insensitive to the amount of silicon precursor injected, indicating that nucleation occurred independently for the iron and silicon components. Light scattering measurements indicate that nanocomposite particles sinter faster than single component silica, in agreement with TEM measurements.

A detailed characterization was performed of the particles produced under various Pb:Si molar feed ratios in a flow reactor at a maximum temperature of 1000 °C. The silica particles formed in the high temperature region coagulated and only partially coalesced to form large agglomerate structures of high specific surface area. For a lead only feed, the resulting particles were hydrocerussite with small but detectable amounts of massicot. As the silica precursor was inlet in excess amounts (Pb:Si ≤ 1:12), the crystalline lead compounds disappeared and amorphous lead-silica complexes predominated. The particle morphology also changed from cylindrical, polygonal and spherical shapes to large agglomerate structures composed of several size modes of primary particles. At Pb:Si molar feed ratios of 1:12 and 1:29, the particles making up the chain-like agglomerate structure were primarily spherical with larger lead silicate spherical particles (≈ 0.5 μm) attached to the agglomerate. The lead was found to be distributed throughout the large agglomerate structures.

The oxygen desorption kinetics of the YBa2Cu3O7‐δ powders generated by an aerosol route was investigated and compared to that of solid state reacted powders. The oxygen content of the aerosol sample was determined using a thermogravimetric analyzer (at 990 C) and wet chemical methods, and δ was calculated to be ‐0.1. The activation energy and pre‐exponential factor were determined by regression for two peaks at 540 C and 850 C. Other activation parameters were also calculated. The calculated values of these parameters for aerosol samples and those reported for solid state reacted powders are in good agreement.