Engineering of highly active Au/Pd supported on hydrogenated urchin-like yolk@shell TiO2 for visible light photocatalytic Suzuki coupling

Abstract

Efficient smart photocatalysts and their surface engineering are necessary for the effective conversion of light energy into chemical energy in photocatalyzed organic reactions. Herein, we designed a hydrogenated urchin-like yolk@shell TiO₂ structure decorated with Au and Pd nanoparticles (HUY@S-TOH@AuPd) as a robust photocatalyst for C–C coupling reactions. The resulting architecture exhibits considerable photocatalytic performance in Suzuki coupling reactions under visible light irradiation with a turnover frequency (TOF) value as high as 7095 h⁻¹. The beauty of this engineered structure lies on the following four points: (I) the urchin-like structure provided a large accessible surface area for high light harvesting as well as high noble metal anchoring; (II) the yolk@shell mesoporous architecture improved the absorption of light by multiple scattering; (III) the presence of Ti³⁺ species on the surface of TiO₂ decreased the band gap of the structure to the visible region; (IV) the enriched electron density of Pd through the injection of hot electrons from Au as well as the flow of electrons from the titanium dioxide semiconductor to the metals accelerated the rate-determining step. The merging of bimetallic plasmonic nanoparticles and urchin like yolk–shell hydrogenated titanium dioxide architecture can open an avenue for designing photocatalysts with high stability and promising activity as well as high direct harvesting of visible light for a broad range of photocatalytic organic reactions.