Internal and External Cultivation: Unleashing the Potential of Carrier Kinetics to Boost Photocatalytic Water Purification

ABSTRACT Precise regulation of carrier kinetics in heterogeneous photocatalytic materials to improve water purification is crucial for alleviating the global water crisis. Herein, we report the successful synthesis of a novel KBC/CeO 2 /Cd 0.5 Zn 0.5 S (KCCZS) S‐scheme heterojunction with KOH‐activated biochar (KBC) as an electron transport medium. A synergistic mechanism involving “surface active sites–internal electric field (IEF)–optimized carrier kinetics” is established, achieving rapid imidacloprid (IMI) removal. Comprehensive characterizations and DFT calculations validate the “internal and external cultivation” strategy, for which photogenerated carriers are efficiently separated spatially by IEF at the heterojunction interface. Concurrently, KBC functions as an “electron pump” to continuously supply electrons, further enhancing carrier generation and separation efficiency. Under visible light irradiation, 10%KCCZS exhibits exceptional IMI removal performance (99.4%, 30 min) with a rate constant of 0.1521 min −1 , representing 23.0 times higher than CeO 2 (0.0066 min −1 ) and surpassing most previous reports. Furthermore, the catalyst maintains excellent purification performance across a broad pH range (3–11), complex water matrices (interfering ions/organics), and various organic pollutants. Mechanistic investigations confirm effective utilization of photogenerated carriers and the dominant role of •O 2 − . LC‐MS analysis coupled with comprehensive toxicity assessment (computational toxicity and biological culture assays) elucidates the IMI degradation pathways and environmental safety. This “internal and external cultivation” strategy fundamentally improves carrier kinetics, not only providing innovative perspectives for future heterojunction design but also paving the way for green and sustainable water purification technologies.