Covalent Organic Cage‐Based Photocatalysts for Highly Efficient and Selective H 2 O 2 Production

ABSTRACT Photocatalysts are key to sustainable hydrogen peroxide (H 2 O 2 ) production, yet most reported systems are polymeric or composite, with limited solubility and poorly defined architectures that obscure mechanistic understanding and structure–function relationships. Here we present covalent organic superphane cages bearing secondary amine, tertiary amine, or ammonium functionalities as discrete, metal‐free photocatalysts for H 2 O 2 generation. Among them, the tied tertiary amine derivative ( SUPE‐ptz‐2 ) exhibits enhanced light absorption, efficient charge carrier separation and transfer, and precisely organized redox‐active sites. As a result, SUPE‐ptz‐2 achieves an H 2 O 2 production rate of 11,089 µmol h − 1 g − 1 in oxygen‐saturated water, rising to 25,031 µmol h − 1 g − 1 with 10% isopropanol, with an apparent quantum yield of 29.2% at 400 nm and 93% selectivity for the two‐electron oxygen reduction pathway. Comprehensive experimental investigations combined with density functional theory calculations reveal that phenothiazine moieties facilitate water oxidation via the four‐electron WOR pathway, while amine groups promote oxygen reduction through both the two‐electron ORR1 and ORR2 pathways; the tied cage architecture enforces spatial separation of redox sites, stabilizes key reaction intermediates, and enhances charge transport. Beyond photocatalytic efficiency, SUPE‐ptz‐2 demonstrates robustness across diverse water sources and enables sunlight‐driven disinfection. These results establish covalent‐organic superphane cages as photocatalysts (singzymes) for sustainable H 2 O 2 generation and broaden their potential in solar‐to‐chemical energy conversion and environmental applications.