Bimetallic Plasmonic Nanoparticle Lattices for Photocatalytic Chemical Transformations

Plasmonic metasurfaces offer unique opportunities to manipulate light at the nanoscale and drive photocatalytic reactions, but fabrication challenges and inefficient catalytic interfaces have limited their use in heterogeneous catalysis. Here, we report scalable bimetallic metasurfaces, fabricated by combining soft lithography with templated chemical synthesis, that consist of centimeter-scale arrays of spiky Au nanoparticles decorated with Pt (spiky Au@Pt). These arrays enhance the rate of the hydrogen-deuterium exchange reaction (H₂ + D₂ ⇋ 2HD), a benchmark photocatalytic process, by 13-fold compared to smooth Au@Pt arrays and reduce the apparent activation energy by nearly half. This activity also exceeds that of similar planar photocatalyst systems reported previously, even at lower illumination intensities. Wavelength-dependent activity, electromagnetic simulations, and quantum-based calculations reveal that strong near-field confinement at sharp Au tips and resonant gap-plasmon excitation promote plasmon-enhanced reactivity, highlighting nanoscale morphology engineering as a pathway to improve photocatalytic metasurfaces.