Surface active sites of Y-doped Zn(O,S) for chemisorption and hydrogenation of azobenzene and nitroaromatic compounds under light via self-generated proton

Abstract

Y-doped Zn(O,S) nanocatalysts with different Y amounts have been fabricated, characterized, and applied for photocatalytic hydrogen evolution reaction (HER) and hydrogenation reaction (PHR) to reduce nitro groups and to cleave azo (NN) bond. The oxysulfide formation was confirmed by XRD, SAED, and DRS analyses. The best Y-doped Zn(O,S) could evolve hydrogen by 3,946 μmol g−1h−1 in aqueous solution with ethanol as a hole scavenger reagent. The PHR of 5% Y-doped Zn(O,S) could hydrogenate 4-nitrophenol to 4-aminophenol and nitrobenzene to aniline in 120 and 90 min, respectively in a low-power UV light illuminated condition (16 W) as confirmed with UV–Vis spectroscopy. Besides of that, a sluggish cleavage of NN bond in azobenzene could be totally done to yield aniline within 30 min. Lastly, the detail mechanisms of HER and PHR including their molecular chemisorption phenomena were proposed and described with the steps of solvation, adsorption, pinning, and surface hydrogenation reactions.