Platinum Single Atoms Strongly Promote Superoxide Formation in Titania‐Based Photocatalysis – Platinum Nanoparticles Don't

Abstract The selective reduction of molecular oxygen to superoxide is one of the key reactions in electrochemistry and photocatalysis. Here the effect of Pt co‐catalysts, dispersed on titania, either as single atoms or as nanoparticles, on the photocatalytic superoxide ( • O 2 − ) formation in O 2 containing solutions is investigated. The • O 2 − formation is traced by nitroblue tetrazolium (NBT) assays and in detail by EPR measurements using TEMPO as • O 2 − radical scavenger. The results show that the photocatalytic formation rate of • O 2 − on titania can strongly be enhanced by using Pt single atoms as a co‐catalyst, whereas Pt nanoparticles hardly exhibit any accelerating effect. This finding is of considerable significance regarding photocatalytic degradation and photocatalytic oxidative synthesis processes.