Synergistic Enhancement Effect of Piezoelectricity and Surface Plasmon Resonance: Boosting Photoelectrochemical Performance for Advanced Biosensing

Regulating the generation, migration, and separation of photogenerated carriers is of great importance for improving the capability of photoelectrodes, which also provides advantages for construction of high-performance photoelectrochemical (PEC) biosensors. Herein, we report an excellent photoelectrode with a synergistic enhancement effect of piezoelectricity and surface plasmon resonance. The photoelectrode, named Au_NP/CdS_NR/ITO, was fabricated via in situ growth of hexagonal wurtzite cadmium cesium nanorod (CdS_NR) arrays on indium tin oxide (ITO) using a hydrothermal method followed by the photodeposition of gold nanoparticles (Au_NP). Mechanism study reveals that the synergistic enhancement effect on Au_NP/CdS_NR/ITO greatly enhances the photoelectron conversion efficiency and facilitates the efficient separation of photogenerated carriers, thus manifesting an ultrahigh photocurrent of 1.06 mA. By virtue of target-triggered 3,3',5,5'-tetramethylbenzidine dication etching technology, a split-type PEC immunosensor was constructed using Au_NP/CdS_NR/ITO as a proof of concept for highly sensitive and precise detection of carbohydrate antigen 199 with a low detection limit of 5.6 × 10^-5 U mL^-1. The study offers insight into improving photoelectrode property through the regulation of the transport process of photogenerated carriers and also developing high-performance biosensors for more biomolecules.