Multifunctional Pt–Ag Janus nanoparticles: photocatalytic H₂ generation and nanomotors activity observed by in-situ LC-TEM

Bimetallic co-catalysts exhibit significantly higher hydrogen photogeneration efficiency compared to their monometallic counterparts. The morphology and shape of nanoparticles also play a crucial role in determining their photocatalytic activity. Previous studies indicate that bimetallic nanoparticles used as co-catalysts were characterized by higher efficiency due to the exposed planes. The shape engineering and impact of Janus-type Pt–Ag co-catalysts remain unexplored. In this study, we report for the first time the design of innovative Janus-type co-catalysts, each consisting of a single platinum nanocube connected to a spherical silver particle of various sizes. A simple and controllable synthesis method for these well-defined structures has been developed. It was demonstrated that the silver content in the Janus structures, used as co-catalysts deposited on the surface of SrTiO₃ semiconductors, significantly influences the hydrogen generation efficiency under UV-Vis light. The use of different co-catalysts resulted in varying H₂ photogeneration efficiencies, following the trend: Pt–Ag JNPs (size of Ag∼20-50 nm) > Pt–Ag JNPs (size of Ag∼60-100 nm) > Pt NPs. Importantly, the developed nanostructures offer dual functionality - not only as efficient co-catalysts for photocatalytic hydrogen production but also as active nanomotors propelled by hydrogen peroxide (H₂O₂). For the first time, we present real-time observation of their motion using in-situ liquid cell transmission electron microscopy (LC-TEM), allowing precise tracking of their dynamic behavior at the nanoscale.