Wavelength-Specific Product Desorption as a Key to Raising Nitrile Yield of Primary Alcohol Ammoxidation over Illuminated Pd Nanoparticles

Research on visible-light photocatalysts of metal nanoparticles (NPs) has focused on increasing the reactant conversion by light-excited charges (electrons and positively charged holes). However, light irradiation can accelerate catalysis by other mechanisms. Here, we report that 650 nm wavelength irradiation of 0.75 W·cm–2 significantly increases nitrile yield of ammoxidation of primary aromatic alcohols with an ammonium salt over supported Pd NPs at 80 °C in air. We found that the desorption of the nitrile product from the catalyst is the rate-determining step; the irradiation promotes not only alcohol oxidation and subsequent aldehyde cyanation over the Pd NPs but also the nitrile desorption selectively via resonance energy transfer to achieve a high nitrile yield. This new mechanism provides a knob for the exquisite control of catalytic reaction pathways for ecofriendly synthesis.