Hot hole multiplication from silver plasmon-resonated gold interband transitions for enhanced photoelectrochemical sensing

Compared with the widespread exploitation of hot electrons in plasmonic nanoparticles (NPs), hot holes generated from plasmonic metal interband transitions, are often overlooked in photoelectrochemistry, including photoelectrochemical sensing. Motivated by the subtle spectral overlap between the characteristic plasmonic bands of Ag NPs and interband transitions of Au, herein, we construct unusual core-shell Ag@Au NPs via an anti-galvanic reaction to promote the generation of hot holes. Benefiting from the unique plasmon resonances of Ag cores in specific wavelength regimes, Ag@Au can excite multiplied hot holes while Au cannot under the same conditions. With satisfactory accuracy and good practicability, the photoelectrochemical sensing platform based on Ag@Au NPs possesses a detection limit of 77 nmol/L for glucose, exhibiting significantly higher sensitivity compared to that using Au NPs. This work exemplifies the applications of interband hot-hole accumulation initiated by plasmons and may inspire more strategies to explore the utilization of hot holes in photoelectrochemistry.