Defect engineering of In2S3 nanoflowers through tungsten doping for ultrasensitive visible-light-excited photoelectrochemical sensors

Abstract

The design of photoactive materials is critical for enhancing the performance of photoelectrochemical (PEC) sensing platforms. In this work, a novel tungsten-doped In₂S₃ (In₂S₃:W) nanostructure with excellent PEC performance (six-fold enhancement compared to the pristine In₂S₃:W) was prepared by a dissolution–regrowth process for ultrasensitive biosensing. We show that the high-valence dopant W⁴⁺ in the In₂S₃ material introduced impurity energy levels and defects that can improve the separation of photo-carriers and therefore enhanced the PEC performance. This mechanism was also confirmed by density functional theory calculations. The designed defective In₂S₃:W material offers a highly active and stable platform for PEC applications. By using the In₂S₃:W material as a signal indicator, a PEC sensing platform for cancer biomarkers, vascular endothelial growth factor (VEGF₁₆₅), was established with the assistance of the target-induced exponential amplification reaction and enzymatic biocatalytic precipitation reaction. The results demonstrated that the PEC sensor exhibited excellent performance with a sensitivity of 0.3 fM due to the high initial PEC signal and photo-carrier separation efficiency of In₂S₃:W. This work gives an in-depth understanding of the enhancement of PEC performance by defect engineering and provides a new PEC sensing platform for bioanalysis and diagnosis.