Bias‐Free Photoelectrochemical System for Scalable Solar‐Driven Hydrogen Peroxide Production via Molecularly Engineered Conjugated Polycarbazole Frameworks

Abstract

Abstract Solar‐driven photoelectrochemical (PEC) synthesis emerges as a promising pathway to produce hydrogen peroxide (H 2 O 2 ), reimagining the energy‐intensive anthraquinone method. However, scaling PEC systems from laboratory‐scale prototypes to practical large‐area installations remains a significant scientific and engineering challenge, primarily due to limited catalytic selectivity at photoelectrode surfaces and rapid performance degradation during upscaling. This study presents a modular, bias‐free PEC system designed for scalable solar‐driven H 2 O 2 production. Conjugated polycarbazole frameworks (CPFs) containing rationally designed diacetylene and anthraquinone moieties functions as molecularly precise catalytic layers, enabling concurrent two‐electron pathways at both the photoanode and photocathode. The resulting photoanode and photocathode deliver faradaic efficiencies of 94.08% and 95.50%, respectively, for H 2 O 2 production. Integrating these photoelectrodes into a 1 cm 2 unbiased tandem PEC device achieves a solar‐to‐chemical conversion (SCC) efficiency of 2.11%. More importantly, scaling these devices to a 1 m 2 membrane‐free PEC panel reactor via a modular assembly strategy yields an average SCC efficiency of 1.10% under natural sunlight, representing the largest reported solar‐driven PEC system for H 2 O 2 production to date. This study bridges the gap between laboratory‐scale experimentation and real‐world applications, providing a scalable framework for decentralized, solar‐driven H 2 O 2 production.