Dynamic Control of Elementary Step Energetics via Pulsed Illumination Enhances Photocatalysis on Metal Nanoparticles

Photon illumination of metal nanoparticle catalysts can promote reaction rate and selectivity through transient charge transfer to adsorbed species. Here we demonstrate that illumination of 2 nm diameter Pt nanoparticle catalysts with pulsed visible light enhances time-averaged rates of H-2 production via methanol decomposition compared with static illumination. Based on CO temperature-programmed desorption, in-situ FTIR, and kinetic measurements, we propose that pulsed illumination promotes reaction rates compared to static illumination by oscillating the binding energy of surface intermediates at frequencies that are in resonance with reaction kinetics. We also show that the impact of light is chemically specific, influencing some elementary step energetics more than others. Our results suggest that using light pulses to dynamically control the energetics of elementary steps on catalytic surfaces may enable higher activity or selectivity than is possible with static illumination or dictated by linear free energy scaling relations.