Insights into the Influence of the Potassium Ion on the Charge Carrier Kinetics of Potassium Poly(heptazine imides)

Understanding the influence of potassium ions (K⁺) on the charge carrier kinetics of potassium poly(heptazine imide) (K-PHI) is crucial for the rational design of efficient PHI-based photocatalytic materials. Herein, we prepare a series of K-PHI photocatalysts with varying K⁺ contents while maintaining constant cyanamide group content and conduct comprehensive femtosecond transient absorption (fs-TA) studies on them. The successful modulation of the K⁺ content in K-PHI samples was confirmed through FTIR, XRD, SEM-EDX, and ICP-OES measurements. A decay process with an ∼62 ps time constant was observed in the fs-TA kinetics of K-PHI samples, in which its amplitude increases linearly with K⁺ content in K-PHI samples, indicating that K⁺ plays a crucial role in modulating the ∼62 ps decay process of K-PHI materials. These findings provide valuable insights into the influence of K⁺ on the charge carrier kinetics and photophysical properties of K-PHI, offering a theoretical foundation for the design of efficient PHI-based photocatalytic materials.