Nano gold coupled black titania composites with enhanced surface plasma properties for efficient photocatalytic alkyne reduction

A nanocomposite design is proven for achieving efficient, selective, and robust alkyne semi-hydrogenation through photocatalytic process, which avoids the use of additional heat sources and traditional toxic Pb additives. The gold nanoparticles (Au NPs) coupled crystalline-core@amorphous-shell structured and wide-spectrum-responsive black titania (BT) with enhanced surface plasma properties holds the key to attaining high activity and selectivity. The hot electron injection from conductive BT to the surface of plasmonic Au NPs stimulated by solar light activates the alkynes and directly participates in the selective conversion to overcome the energy barriers. The engineered Au/BT gives a record turnover frequency of 1012 h −1 and excellent stability for phenylacetylene semi-hydrogenation under solar light irradiation and shows broad scope toward selective hydrogenation of alkynes containing various substituent groups of –CH 3 , –OH, and –Cl. The kinetic isotope effects and in situ infrared spectroscopy analysis for structure-activity relationship and reaction mechanism of phenylacetylene reduction were also demonstrated. • Nano gold coupled black titania composites show excellent surface plasma properties. • Au/BT exhibits high activity for photocatalytic phenylacetylene semi-hydrogenation. • Kinetic isotope effects and in situ infrared probe the crucial reaction processes. • A three-step reaction mechanism involved phenylacetylide species is proposed.