The cover picture shows the degradation of the model dye rhodamine B (RhB) in water using β-Bi2O3 nanoparticles as photocatalyst, which was prepared from preorganized bismuth oxido clusters. In the background, a homemade photoreactor for in situ studies is shown, including the decolorizing process of the aqueous RhB solution as observed during visible light irradiation. The catalytic cycle shows crucial steps in RhB degradation at the surface of β-Bi2O3 nanoparticles (balls), which can be recycled. After adsorption of RhB at the surface of β-Bi2O3 nanoparticles, the color of the nanoparticles changes from orange to violet. The degradation process (represented by Pac-Man) is induced by irradiation with visible light, resulting in a complete decolorization of the solution as well as the surface of the β-Bi2O3 nanoparticles, indicating a fast de-ethylation process. The latter process is faster than desorption of partially degraded RhB species from the β-Bi2O3 surface, but is demonstrated to occur upon irradiation of RhB-loaded β-Bi2O3 in the solid state. For more details, see the Full Paper by Michael Mehring et al., on p. 146 ff.