Polypyrrole-Modified Lead-Free Perovskite Heterojunctions to Facilitate Charge Separation for Photocatalytic Oxidation of Benzylamine.

Integrating electron-donor and electron-acceptor components into a heterojunction photocatalyst presents a significant challenge for enhancing light harvesting and charge separation. Meanwhile, developing efficient and selective photocatalysts for aerobic oxidative coupling of benzylamine under mild conditions remains highly desirable. Herein, we construct a polypyrrole-Cs2AgBiBr6 heterojunction via an in situ growth strategy, in which polypyrrole nanostructures serve as highly efficient conducting polymer nanoarchitectures (CPNs) to promote charge dynamics. As a heterogeneous photocatalyst for the aerobic oxidation of benzylamine at ambient temperature, the optimized PPy-CABB composite delivers a remarkably enhanced imine production rate of 4762 μmol·g-1·h-1, accompanied by an apparent quantum yield (AQY) of 20.1%. Under strictly identical reaction conditions, the composite exhibits higher catalytic activity and broad substrate tolerance than the reference composites tested in this work. Systematic experiments reveal that the incorporation of PPy CPNs significantly facilitates interfacial charge separation and migration, thereby suppressing electron-hole recombination and promoting the generation of reactive oxygen species such as superoxide radicals (•O2-) and singlet oxygen (1O2). This work highlights the pivotal role of CPNs in advancing heterojunction photocatalysis and offers a feasible strategy for designing efficient light-harvesting systems toward solar-energy conversion.