Cooperative dehydrogenation coupling of isopropanol and hydrogenation coupling of acetone over a sodium tantalate photocatalyst

Photocatalytic organic syntheses are often limited by their low system efficiency and product selectivity. We demonstrate herein that intermolecular hydrogen transfer from isopropanol to acetone can be achieved efficiently on the surfaces of NaTaO₃ photocatalysts, on which 2-hydroxyisopropyl radicals are produced selectively from both oxidation and reduction half-reactions and then coupled to form 2,3-dimethyl-2,3-butanediol. Such a process effectively increases the total reaction efficiency. We also found that the two half-reactions occur at different crystal facets and display a remarkably promotive interaction, which dramatically speeds up the reactions by one order of magnitude and significantly restrains side reactions. The sodium ions on the NaTaO₃ surfaces play an important role in the promotive effect, likely facilitating the proton transfer between the oxidation and reduction sites. These factors make the production rate of 2,3-dimethyl-2,3- butanediol reach a very high level (10.87 mmol g^-1 h^-1), emphasizing the potential of photocatalytic hydrogenation and dehydrogenation in improving system efficiency of photocatalytic organic syntheses. Double couple: Dehydrogenation coupling of isopropanol and hydrogenation coupling of acetone can be performed simultaneously on a single NaTaO₃ photocatalyst through intermolecular hydrogen transfer and display a remarkable promotive interaction, which speeds the reactions by one order of magnitude and restrains side reactions. CB=conduction band, VB=valence band.