Selective Photocatalytic Synthesis of Haloanilines from Halonitrobenzenes over Multifunctional AuPt/Monolayer Titanate Nanosheet

Bimetallic alloy AuPt nanoclusters supported on monolayer H1.07Ti1.73O4·H2O nanosheets (AuPt/TN) jointly complete a rapid catalytic reaction toward hydrogenation of halonitrobenzene to haloaniline in methanol under ambient conditions using HCOONH4 as a hydrogen source. Especially, AuPt/TN with a Au/Pt molar ratio of 1:2 exhibits the high catalytic conversion efficiency for halonitrobenzene (>99%) with a high selectivity of haloaniline (>99%). In situ FTIR spectra suggest that the TN affords surface Brønsted acid sites to chemisorb and activate the halonitrobenzene molecules via the surface hydrogen bond coordination. In situ ESR experiments indicate that HCOONH4 would be decomposed to H+ and a •CO2– radical by photogenerated holes, serving as the hydrogen source and reducing species for the reduction of the −NO2 group, respectively. Experimental results reveal that atom Pt in alloy is responsible for the hydrogenation, while Au represses the dehalogenation of haloanilines. Finally, a possible synergetic mechanism is discussed. This work highlights that the multifunctional AuPt/TN catalyst with multiple active sites exerts the respective functions to cooperatively catalyze organic transformations toward desired target products.