was not yet the case for the flat substrates. This is likely due to a different distribution and dissipation of the laser energy on the 3-dimensional substrate. Consequently, only one coating step was used for the preparation of TiO2-coated WLE. After the WLEs had been successfully coated, the reduction of nitrobenzene to aniline was investigated. The experiment was performed with 50 coated WLEs immersed in 50 mL of a 10 mM nitrobenzene solution in 2-propanol. This corresponds to a fill factor (WLE volume to total reaction volume) of 35% and a volumetric photon flux density (qp) of 322 µM s -1 (determined via ferrioxalate actinometry). The concentrations of nitrobenzene and aniline were determined by GC analysis, representative concentration-time profiles are shown in Figure . The initial linear aniline formation rate was 0.045 mM min -1 . However, after using the coated WLEs three times, the coating could no longer be seen with the naked eye and scratches were also visible on the WLEs. These likely originated from the high shearing and abrasive forces in the intensely stirred system. Even though this was not accompanied by a decrease in activity (all three consecutive experiments showed the same reaction rates within the expected experimental error, see Fig. ), this shows that further improvement of the coating method may be necessary for prolonged usage under such harsh conditions. In comparison, the experiment was carried out with uncoated WLEs and with free titanium dioxide particles as a photocatalyst, adjusted to the same photon flux density. As expected, the reaction was faster than with the coated WLEs at 0.077 mM min -1 . The reason for this is the much higher amount of photocatalyst (2 g L -1 TiO2 ) and the thus higher exposed catalytic surface. Assuming a layer thickness of 8 µm (which was determined for platelets coated with the same protocol), a WLE half-sphere has a catalyst layer volume of about 2 nL, corresponding to about 8 µg at TiO2 bulk density. This results in an equivalent catalyst concentration of 8 mg L -1 at best for the coated variant, which is 250 times below the value for the free suspension.