A major challenge in utilizing living botanical materials, such as cellular leaf structures, as templates is that they are filled with water and conventional dehydration strategies often collapse or degrade the intricate botanical structure. This restricts the ability to introduce water reactive precursors into such structures. We have developed a room-temperature chemical method using acidified 2,2-dimethoxypropane to dehydrate water-rich botanical materials (e.g., fern leaves and water-rich jade succulents). This mild dehydration process leaves much of the porous cellular leaf structure intact even with ∼90% mass loss. These chemically dehydrated templates have been utilized in the growth of porous and ordered leaf replicate structures consisting of TiO2 and SiO2 via sol-gel precursor impregnation methods. These white metal oxide products exhibit external and internal structures that look very similar to their original templates, but are shrunken intact versions of the original. This paper details the chemical procedures that enable one to effectively use sensitive botanical templates in metal oxide growth. The physical and structural properties of several dried porous templates and macroporous anatase TiO2 and amorphous or crystoballite SiO2 products will be described. Recent efforts to use these botanical templates to produce other porous metal oxides (e.g., Co3O4, NiO, and CuO) using both halide and acetate precursor impregnation strategies are noted. Porous metal oxides with interconnected pore walls may have use in electrochemical energy storage systems, including in photocatalytic, photovoltaic or battery systems.

In this paper, we have studied the energy transport properties of two porphyrincontaining metal organic frameworks (MOFs) for light-harvesting applications. The photoinduced singlet exciton migration is investigated using fluorescence quenching experiments, whereas details on exciton transport anisotropy and net displacements are obtained using a Förster theory analysis. The striking difference in the energy-transport properties for the two MOFs, albeit for similar molecular organization, is attributed to dissimilar spatial expanse and difference in the electronic structure of their porphyrin struts. The observed exciton displacements, of up to 60 nm, provides motivation to explore new MOF materials. Several new linkers are considered, leading to predictions of MOF structures, which provide both broadwavelength harvesting and unidirectional energy transporting MOFs with selected examples.

Anodic oxide formation and chemical and electrochemical etching of n-Si(111) have been investigated in alkaline media. Due to the complexity of the processes, the investigation has been restricted to the initial phase where a transitory anodic photocurrent peak is observed slightly positive from the open circuit potential (ocp). In-system photoelectron spectroscopy, performed at the U 49/2 beamline at Bessy, shows sub-monolayer silicon surface oxidation and remnant H-termination, indicating island-type oxide formation. Scanning probe microscopy shows the formation of macropores with 300-500 nm diameter and an average depth of 5-8 nm. The discussion comprises chemical and electrochemical dissolution mechanisms and routes to development of nanoemitter fuel generating devices.

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.

In this paper we described using ruthenium (Ru) nanoparticles for surface modification on our hybrid PV/a-SiC photocathode for hydrogen production by water splitting under sunlight. Ru nanoparticles with size less than 5nm in diameter made the photocathode showed promising results: in an aqueous electrolyte an anodic shift of photocurrent onset potential around 450 mV and an increase in the photocurrent density up to 1.8mA/cm2 from a negligible value. Initial discussion the influence of Ru nanoparticles is presented.