2019, Krivtsov, Igor, Mitoraj, Dariusz, Adler, Christiane, Ilkaeva, Marina, Sardo, Mariana, Mafra, Luis, Neumann, Christof, Turchanin, Andrey, Li, Chunyu, Dietzek, Benjamin, Leiter, Robert, Biskupek, Johannes, Kaiser, Ute, Im, Changbin, Kirchhoff, Björn, Jacob, Timo, Beranek, Radim

Heptazine-based polymeric carbon nitrides (PCN) are promising photocatalysts for light-driven redox transformations. However, their activity is hampered by low surface area resulting in low concentration of accessible active sites. Herein, we report a bottom-up preparation of PCN nanoparticles with a narrow size distribution (ca. 10±3 nm), which are fully soluble in water showing no gelation or precipitation over several months. They allow photocatalysis to be carried out under quasi-homogeneous conditions. The superior performance of water-soluble PCN, compared to conventional solid PCN, is shown in photocatalytic H2O2 production via reduction of oxygen accompanied by highly selective photooxidation of 4-methoxybenzyl alcohol and benzyl alcohol or lignocellulose-derived feedstock (ethanol, glycerol, glucose). The dissolved photocatalyst can be easily recovered and re-dissolved by simple modulation of the ionic strength of the medium, without any loss of activity and selectivity. © 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.