Rational design of direct Z-scheme heterojunction CdS/polyimide with enhanced adsorption and photocatalytic activity under visible light irradiation

A series of CdS/Polymer heterojunctions were constructed via a facile hydrothermal method. Triangular wurtzite CdS nanocrystals with 10 nm to 15 ​nm were in-situ crystalized and highly dispersed on the surface of Perylene-3,4,9,10-tetracarboxylic diimide (PTCDI) 2D polymers. Characterization results revealed that the CdS/PTCDI heterojunction exhibited enhanced optical absorption (visible region) and visible-light photocatalytic degradation of methyl orange (MO), with the highest pseudo-first-order rate constant surpassing neat CdS by 11.6-fold and pristine PTCDI by 2.4-fold. Controlled experiments and Free radical trapping experiments demonstrated that the improved photocatalytic performance and stability are primarily resulting from the direct Z-scheme electron transfer mechanism at the CdS/PTCDI heterojunction interface, which not merely boosts charge separation and transfer but effectively suppresses the photocorrosion of CdS. This study demonstrates the multifunctional roles of conjugated polymers in fabricating high-performance heterogeneous photocatalysts.