Oxygen vacancies and Bi2S3 nanoparticles co-sensitized TiO2 nanotube arrays for enhanced photoelectrochemical sensing of chlorpyrifos

Due to the environmental pollution and food safety problems that caused by the abuse of chlorpyrifos (CPF), a strategy of which is detected with high efficiency is urgently demanded. Herein, a photoelectrochemical sensor which using TiO2 nanotube arrays with oxygen vacancies (Vo-TNTAs) as electrode was constructed. Oxygen vacancies are introduced into TNTAs in order to generate a new defect level that narrows its band gap. The bismuth sulfide nanoparticles are loaded on Vo-TNTAs to accelerate the separation of electron-hole pairs. Thus, the Bi2S3/Vo-TNTAs hetero-structure is designed and constructed. With the existence of CPF, a complex which composed by Bi ions and CPF will be formed in situ to block the electrons transfer from electron donor (ascorbic acid) to Bi2S3, causing the weakened photocurrent. Consequently, the Bi2S3/Vo-TNTAs electrode possess higher photocurrent response than that of pure Vo-TNTAs and TNTAs. The Bi2S3/Vo-TNTAs-based PEC sensor displays a linear range of 0.07–3.0 μmol/L with a detection limit of 6.0 nmol/L (S/N = 3) and can be utilized for CPF detection in lettuce and cucumber samples with recoveries of 95.7 to 110 %.