Palladium single atoms on TiO2 as a photocatalytic sensing platform for analyzing organophosphorus pesticide chlorpyrifos.

Traditional methods for analyzing organophosphorus pesticide chlorpyrifos, usually require the tedious sample pretreatment and sophisticated bio-interfaces, leading to the difficulty for real-time analysis. Herein, we use palladium single-atom (PdSA)/TiO2 as a photocatalytic sensing platform to directly detect chlorpyrifos with high sensitivity and selectivity. PdSA/TiO2, prepared by an in situ photocatalytic reduction of PdCl42- on the TiO2, shows much higher photocatalytic activity (10 mol g(-1) h(-1)) for hydrogen evolution reaction than Pd nanoparticles (1.95 mol g(-1) h(-1)), and excellent stability. In the presence of chlorpyrifos, the photocatalytic activity of PdSA/TiO2 decreases. Through this inhibition effect the platform can realize a detection limit for chlorpyrifos of 0.01 ng mL(-1), much lower than the maximum residue limit (10 ppb) permitted by the U.S. Environmental Protection Agency.