Tailoring Plasmonic Bimetallic Nanocatalysts Toward Sunlight‐Driven H2 Production

Hybrid nanoparticles combining plasmonic and catalytic components have recently gained interest for their potential use in sunlight‐to‐chemical energy conversion. However, a deep understanding of the structure–performance that maximizes the use of the incoming energy remains elusive. Here, a suite of Au and Pd based nanostructures in core–shell and core‐satellites configurations are designed and their photocatalytic activity for Hydrogen (H2) generation under sunlight illumination is tested. Formic acid is employed as H2 source. Core‐satellite systems show a higher enhancement of the reaction upon illumination, compared to core–shell ones. Electromagnetic simulations reveal that a key difference between both configurations is the excitation of highly localized and asymmetric electric fields in the gap between both materials. In this scheme, the core Au particle acts as an antenna, efficiently capturing visible light via the excitation of localized plasmon resonances, while the surrounding Pd satellites transduce the locally‐enhanced electric field into catalytic activity. These findings advance the understanding of plasmon‐driven photocatalysis, and provide an important benchmark to guide the design of the next generation of plasmonic bimetallic nanostructures. Geometrical arrangement of both the plasmonic and the catalytic components on bimetallic nanocatalysts strongly influences the activation of the catalytic constituent. The inherent absorption of Pd is boosted when it is deposited as a thin layer onto a plasmonic nanoparticle. However, through the creation of optical hotspots, this absorption process is locally increased when Pd is shaped into satellites and placed around the same plasmonic nanoparticle, converting the optical hotspot into a highly active chemical hotspot.