Photoredox Cascade Catalysis for Hydrogen Production With Wacker Oxidation of Olefin Gases

Solar-light-driven photocatalytic coproduction of hydrogen (H₂) and valuable organic compounds is a promising technique for realizing sustainable carbon neutral society. In this work, we fabricate a new dual-product photocatalytic system for the coproduction of H₂ and acetaldehyde/acetone by combining a dual Ru (II) dye-sensitized Pt-cocatalyst-loaded TiO₂ nanoparticles photocatalyst with a Pd(II)-acetate/9-azanoradamantane N-oxyl (nor-AZADO•) double-mediatory Wacker oxidation catalytic system. This photoredox cascade catalytic system successfully converts gaseous ethylene/propylene substrates into H₂ and acetaldehyde/acetone under blue-light irradiation owing to the electron mediation of nor-AZADO• between the two (photo)catalytic cycles. The maximum turnover number per one photosensitizer and apparent quantum yield for the initial 1 h of irradiation in the presence of 5.0 vol% ethylene gas are estimated to be 1533 and 1.23%, respectively. These findings open a new avenue for simultaneously supplying clean energy resources, H₂ and organic valuables via oxidative organic transformations.