Hollow ZnS–CdS nanocage based photoelectrochemical sensor combined with molecularly imprinting technology for sensitive detection of oxytetracycline

A novel hollow ZnS–CdS nanocage-based molecularly imprinted photoelectrochemical (ZnS–CdS/rMIP PEC) sensor was designed for sensitive detection of oxytetracycline (OTC). O-phenylenediamine was electropolymerized onto hollow ZnS–CdS nanocages to form a polymer film, and then OTC molecules were imprinted on the polymer film through hydrogen bonding. When OTC was eluted, many specific recognition sites were formed on the polymer membrane for detecting OTC in samples. It is worth noting that the rhombohedral dodecahedral structure of hollow ZnS–CdS nanocage can provide large specific surface area, allowing more OTC molecules to be imprinted into the polymer film. Moreover, the unique hollow structure and the heterojunction formed by ZnS and CdS can significantly enhance the photocurrent response. Furthermore, molecular imprint polymer (MIP) technology greatly improves the selectivity and sensitivity of the constructed PEC sensor for detection of OTC. Under optimal conditions, the ZnS–CdS/rMIP PEC sensor has prominent linear relationship in the range of OTC concentration from 1 nmol L⁻¹ to 3 μmol L⁻¹, and the detection limit is 0.10 nmol L⁻¹ (S/N = 3). It is gratifying that the fabricated ZnS–CdS/rMIP PEC sensor displays excellent selectivity for OTC detection when interferences with similar structure exist. It also exhibits superior reproducibility and stability as well as high recovery in the investigation of actual water samples. The combination of PEC and MIP technology will provide significant reference value for effective and rapid detection of other pollutants in the environment.