Coupled tri-electric fields synergy promotes migration of bulk-surface charges for enhancement of photocatalytic U(VI) removal

Enhanced bulk-surface charges separation and migration are essential to maximize the photocatalytic activity. In this study, ethylenediamine (EDA)-modified Zn 0.7 Cd 0.3 S nanorods (ZCS-NR-EDA) were synthesized through an integral modification approach. After 1-hour adsorption equilibrium followed by 6-minute co-irradiation with visible light and ultrasonic waves, ZCS-NR-EDA removed 99.2 % of U(VI) from the solution, significantly better than Zn 0.7 Cd 0.3 S nanoparticles (ZCS-NP) (13.6 %) and Zn 0.7 Cd 0.3 S nanorods (ZCS-NR) (25.3 %). This catalytic performance has outperformed most reported materials. Experimental and density functional theory (DFT) calculation studies confirmed that EDA modification induced polarization to establish a bulk electric field (BEF) and modified the electron distribution at the material's surface to create localized surface electric field (LSEF), while simultaneously enhancing the material's piezoelectric properties. The synergistic effect of these triple electric fields (polarization-induced BEF, LSEF, and piezoelectric field (PF)) promoted migration of bulk-surface charges, thereby enhancing catalytic performance. When applied to uranium spiked tailing water, ZCS-NR-EDA achieved up to 98.1 % U(VI) removal within 15 min of combined visible light and ultrasonic irradiation (after adsorption equilibrium). More importantly, this “tri-electric fields synergy” strategy provides a novel approach for the design of advanced photocatalytic materials.