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We have developed an efficient, low temperature, synthetic route for ZnO nanoflowers (NFs) as photoanode material. This alternative route yields small flowerlike nanostructures, built from densely self-assembled tip-ended rod structures. The obtained ZnO NFs possess a large bandgap of 3.27 - 3.39 eV, enabling the generation of an average open current voltage of 0.56 V. Additionally, they show a high internal light harvesting of 14.6•10-7A-mol-1. The growth mechanism and self-assembly of ZnO NFs were studied in detail by joint spectroscopic-TEM investigations. It is shown that the ZnO crystallite size increases with increasing annealing temperatures and that the stress and the improved crystallinity are induced by annealing and reduce the lattice strain and the dislocation density. The bandgaps of ZnO are affected by the lattice strain revealing an optimal region of lattice strain to gain high bandgap energies. The properties of the synthesized ZnO NFs are compared with other morphologies, i.e. ZnO spherical aggregates (SPs) and ZnO nanorods (NRs), and are tested as electrode materials in dye-sensitized solar cells.

Lithium and sodium thiophosphates (and related compounds) have recently attracted attention because of their potential use as solid electrolytes in solidstate batteries. These compounds, however, exhibit only limited stability in practice as they react with the electrodes. The decomposition products partially remain redox active hence leading to excess capacity. The redox activity of thiophosphates is explicitly used to act as electrode for sodium-ion batteries. Copper thiophosphate (Cu 3 PS 4 ) is used as a model system. The storage behavior between 0.01 and 2.5 V versus Na + /Na is studied in half cells using different electrolytes with 1 m NaPF 6 in diglyme showing the best result. Cu 3 PS 4 shows highly reversible charge storage with capacities of about 580 mAh g −1 for more than 200 cycles @120 mA g −1 and about 450 mAh g −1 for 1400 cycles @1 A g −1 . The redox behavior is studied by operando X-ray diffraction and X-ray photoelectron spectroscopy. During initial sodiation, Cu 3 PS 4 undergoes a conversion reaction including the formation of Cu and Na 2 S. During cycling, the redox activity seems dominated by sulfur. Interestingly, the capacity of Cu 3 PS 4 for lithium storage is smaller, leading to about 170 mAh g −1 after 200 cycles. The results demonstrate that thiophosphates can lead to reversible charge storage over several hundred cycles without any notable capacity decay.