Before starting the irradiation, the reaction solution was recycled through the setup to equalize adsorption of the substances. Depending on the properties of the system, the extent of adsorption varied, resulting in variations of the initial nitrobenzene concentration when the photocatalytic reaction was started. To enable an objective comparison, conversion and selectivities after 30 h and 54 h were calculated and shown in Figure and Table . The temporal evolution of the amounts of reactants can be found in the supporting information.