Latest achievements in the field of photocatalytic conversion of biomass are reviewed, and experimental conditions and results are critically evaluated.

Novel structural battery electrolytes with both high ionic conductivity and stiffness in combination.

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Cu nanoparticles were deposited on the surface of commercial TiO nanoparticles (Cu-TiO) using different methods aiming at the production of highly efficient visible light photocatalysts. Photocatalytic H evolution rates obtained from methanol/water mixtures revealed no significant influence of the presence of copper oxides on the photoreaction upon visible light illumination. The photocatalytic H production rates were evaluated upon illumination with different spectral ranges (≥420 nm or ≥500 nm) and the results evidenced that the visible light induced charge carrier formation on the Cu-TiO photocatalysts consists of two distinct pathways: the direct excitation of TiO and the induced excitation by the so-called surface plasmon resonance (SPR) effect of the Cu nanoparticles on the TiO surface. Both pathways are present when the full visible range of the spectrum is used (≥420 nm), while for illumination at longer wavelengths (≥500 nm), the photocatalytic activity is solely promoted by the Cu-SPR effect. Electron paramagnetic resonance (EPR) and laser flash photolysis measurements were performed to clarify the underlying mechanism of Cu-TiO photocatalysts upon visible light illumination.

Charge carrier recombination kinetics of TiO2 powder samples were analyzed in the time domain ranging from 50 ns to 1 ms. The transient reflectance signals of the charge carriers observed by laser flash photolysis spectroscopy do not fit to simple second order kinetics as expected for the recombination of trapped electrons and holes. The deviation from second order reaction dynamics could rather be explained by the segregation of charge carriers and the fractal dimension of the semiconductor agglomerates. According to the fractal reaction kinetics, the time dependent rate coefficient k f (k f = k 2,f t –h ) has been employed instead of the second order rate constant k 2, where the fractal parameter h describes the dimension of the system. This model could successfully be used to describe charge carrier signals in all observed time domains. Moreover, the model was compared with the concept developed by Shuttle et al., which proposes that the charge carrier signals decay following a power-law. The benefits of the fractal model proposed here include the possibility to describe and analyze influences of the morphology on the fractal parameter h and its applicability over a broad range of time domains and excitation energies.