Benzaldehyde‐Promoted (Auto)Photocatalysis under Visible Light: Pitfalls and Opportunities in Photocatalytic H₂O₂ Production**

Abstract Selective photooxidation of aromatic alcohols to corresponding aldehydes is a widely used model reaction for evaluation performance heterogeneous photocatalysts. A top example the photocatalytic production hydrogen peroxide via reduction dioxygen with concomitant benzyl alcohol benzaldehyde. Herein we demonstrate ability benzaldehyde promote auto‐photocatalytic oxidation and produce large quantities H 2 O in solvent‐free (no water) or biphasic (with systems even under nominally visible (>420 nm cut‐off filter) light irradiation. These results shed critical on plethora research reports which was employed as electron donor. Since autocatalytic pathway based activity formed during photocatalysis such conditions cannot be neglected, interpretations are likely contentious distorted reports. The use donor studies should therefore definitely discouraged. On other hand, found that benzaldehyde‐mediated proceeds also using alternative donors ( e. g ., ethanol), our highlight possible prospects more general light‐driven photocatalysis.