Nonetheless, the experiment shows that although the coated photocatalyst layer is so thin, it is still very active. In our previous study, only a reaction rate of 0.015 mM min -1 was achieved in the same reaction which is 3 times lower than in the present case. A major advantage of the coated variant over freely suspended particles is also that the vast majority of the light is absorbed by the photocatalyst before it passes through the reaction solution. This not only prevents parasitic light absorption, i.e., light being absorbed by components other than the photocatalyst, but also prevents un-wanted photochemical side-reactions as potential consequences of such events.