Janus Au Nanostructure-Empowered Cathodic Photoelectrochemical Analysis: Plasmon-Activated Signaling Cascade...

Exploring an ingenious way to promote the promising cathodic photoelectrochemical (PEC) strategy in complex sample analysis necessitates further improvement. In this study, the Janus Au nanostructure is designed and harnessed to empower the cathodic PEC aptasensing by plasmon-activated signaling cascade amplification coupled with sensing interface engineering. First, the plasmon-promoted signaling cascade amplification of the Au/CuSCN nanorod array (NA) photocathode is primarily attributed to the increased visible light harvesting and accelerated migration of photogenerated carriers, which are further evidenced through a combination of series experimental validations including Mott-Schottky and Tafel plots, as well as density functional theory calculations. Notably, the CuSCN NAs decorated with surfactant-free Au nanostructures exhibit promoted PEC activities due to the injection of plasmonic hot holes, while inhibited PEC activities for surfactant-capped Au nanostructures are ascribed to the inhibitory hot hole injection. Meanwhile, the surfactant-free Au nanostructure is employed to link aptamers for recognition and capture of the target on the photocathodic sensing interface, effectively avoiding these complex matrix interferences in practical detecting applications. A dual-photoelectrode-based PEC sensing system is then created by integrating a high-performance Bi₂S₃-C₃N₄ photoanode with the designed Au/CuSCN NAs photocathode. As a proof of concept, a PEC aptasensing platform is fabricated toward the monitoring of the emerging pollutant streptomycin in water, which offers a promising strategy for the effective and feasible fabrication of the cathodic PEC systems with high performance.