Design of ultrathin nanosheet subunits ZnIn2S4 hollow nanocages with enhanced photoelectric conversion for ultrasensitive photoelectrochemical sensing.

Herein, a high-efficiency photoactive material, hollow ZnIn2S4 nanocages (ZIS-HNCs) composed of ultrathin nanosheets were creatively synthesized via a metal-organic framework (MOF) derived solvothermal method. It had been specified the underlying mechanism of the ZIS-HNCs evolution under the MOF templated surface. Subsequently, the obtained ZIS-HNCs combined with annealing TiO2 modified electrode (ZIS-HNCs@TiO2), and the ZIS-HNCs@TiO2 exhibited intense transient photocurrent. The enhanced photocurrent signal benefited from the multiple light capture effect of ZIS-HNCs, ultrathin nanosheet subunits of ZIS-HNCs, and typical type Ⅱ heterojunction, which could effectively retard the photoexcited electron-hole pairs recombination, and accelerated charge separation and transfer. Taking antibiotic lincomycin (Lin) as a model, a signal-off photoelectrochemical (PEC) aptasensor based on the ZIS-HNCs@TiO2 was established and manifested a high sensitive detection for Lin with a linear response range from 0.0001 to 0.1 nM as well as an ultralow detection limit of 0.084 pM. Additionally, the proposed PEC aptasensor showed acceptable stability and remarkable selectivity. Therefore, this study provides a promising strategy to design nanomaterials with superior photoelectric activity for PEC sensing applications.