Palladium Single Atoms on TiO₂ as a Photocatalytic Sensing Platform for Analyzing the Organophosphorus Pesticide Chlorpyrifos

Abstract 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)/TiO 2 as a photocatalytic sensing platform to directly detect chlorpyrifos with high sensitivity and selectivity. PdSA/TiO 2 , prepared by an in situ photocatalytic reduction of PdCl 4 2− on the TiO 2 , 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/TiO 2 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.