Although photocatalytic H2O2 production at PCN from pure water and oxygen has been reported, typically the presence of additional sacrificial electron donors (e.g., aliphatic or aromatic alcohols) is practically indispensable in order to achieve reasonable reaction rates . The key mechanistic steps proposed in the literature are the protonation of the heptazine nitrogen sites enabled by fast oxidation of the electron donor and the activation of O2 by photogenerated electrons, enabled by the very negative quasi-Fermi level of electrons in PCN (typically ca. -0.7 V vs. RHE ), with subsequent formation of the intermediate heptazine-bound endoperoxide species . While photocathodes for efficient H2O2 production from O2 based, for example, on epindolidione deposited on gold electrodes or porphyrin-sensitized nickel oxide films have been reported recently, there areto the best of our knowledgeno PCN-based photocathodes for selective light-driven reduction of O2 to H2O2 reported so far.