Polyacid-Modulated Carrier Dynamic Behavior at the Interface of 0D/2D Heterojunctions

Heterojunctions formed by polyoxometalates and 2D materials draw attention owing to their remarkable photoelectric and catalytic properties. However, the intrinsic mechanisms of polyoxometalates regulating the heterojunction photoelectric properties are unclear. Herein, we constructed two types of heterojunctions by integrating polyoxometalates (Keggin-type H₃PW₁₂O₄₀ and Lindqvist-type H₂W₆O₁₉) on g-C₃N₄ monolayers, exploring photoexcited carrier dynamics in these heterojunctions by ab initio calculations combined with nonadiabatic molecular dynamics (NAMD) simulations. Our results show that electrons and holes in H₃PW₁₂O₄₀ on g-C₃N₄ monolayers relax within 583 and 760 fs, respectively. The electron-hole recombination occurs at 342 fs, faster than carrier separation, aligning with the behavior of Z-type heterojunctions. Contrarily, the H₂W₆O₁₉/g-C₃N₄ heterojunction exhibits the typical characteristics of type II heterojunctions, with a long photogenerated carrier lifetime reaching 652 fs. These findings show tunable band alignment in polyoxometalate-supported systems by modulating polyoxometalate type, influencing hot electron dynamics, and guiding 0D/2D heterojunction design.