Polarization-induced carrier separation in conjugated polyimide for boosted visible light driven H2O2 production.

[Display omitted] • Conjugated polyimide with tunable polarity is synthesized by a facial solid-state reaction. • PIK 1.5 exhibits 117-folds enhanced photocatalytic H 2 O 2 production compared with PI under visible-light irradiation (λ > 420 nm). • Improved polarization in conjugated polyimide increases the separation and transport efficiency of electron-hole pair. • The photocatalytic reaction is driven by two electron pathways. Ternary carbon nitride oxygen semiconductors have been developed as metal-free catalysts for photocatalysis, but the efficiencies are still far from satisfaction. Herein, we report that polarization adjusted conjugated polyimide (PIK) can be substantially optimized the activity of visible-light induced H 2 O 2 production. The structures of catalyst have been well characterized by XRD, FTIR, BET and XPS. Compared with bulk polyimide, optimized PIK 1.5 displays 117-folds-enhanced photocatalytic H 2 O 2 production under visible light (λ ≥ 420 nm), achieving an excellent H 2 O 2 production rate of 160.5 umol·g·h−1. Fluorescence spectroscopic measurements confirm that reinforced photocatalytic H 2 O 2 production is mainly attributed to the increased polarization in conjugated polyimide, which effectively accelerates the separation and migration kinetics of electron-hole pairs. These results indicate that polarization play an important role in polymeric semiconductors for solar energy utilization. [ABSTRACT FROM AUTHOR]