Atom-sharing Bi/Bi3O4Br plasmonic heterojunctions with effectively boosted photoelectrochemical activity for specific detection of chlorpyrifos

The increased environmental pollution caused by the overuse of the organophosphorus pesticide chlorpyrifos (CPF) has necessitated the development of an effective and selective photoelectrochemical (PEC) sensor. Herein, a Bi atom co-sharing Bi/Bi3O4Br plasmonic heterojunction was synthesized using an in-situ reduction process as a photoelectrode material to develop a highly selective PEC sensor for detecting CPF. Experimental characterizations and theoretical calculations demonstrate that the Bi atom-sharing heterostructure achieves tight contact in the heterointerface and effectively facilitates interfacial charge separation and migration. In addition, the deposition of Bi could greatly increase light-harvesting capacity of semiconductor materials resulting from the surface plasmon resonance (SPR) effect. Moreover, after the addition of CPF, the chelation between Bi3+ and C=N and P=S bonds in CPF hinders the mobility of photogenerated charges, leading to a decrease in the photocurrent signal intensity and selective determination of CPF. Compared to pristine Bi3O4Br, the proposed Bi/Bi3O4Br plasmonic heterojunction exhibits superior PEC activity. The developed PEC sensor showed a wide linear range (0.01–2000 ng/mL), a low detection limit of 0.0017 ng/mL (S/N=3), and superior selectivity and stability (RSD = 6.68%), which can be applied to CPF detection in tap water samples with recoveries of 97.2. to 102.9%. This study contributes to the rational design of a low-cost, highly efficient, and stable Bi-based plasmonic heterojunction for the CPF detection.