Cu@CuOx/WO3 with photo-regulated singlet oxygen and oxygen adatoms generation for selective photocatalytic aromatic amines to imines.

[Display omitted] • The WO 3 decorated with Cu was developed to efficiently regulate O 2 active species. • Under irradiation of wavelength < 475 nm, O 2 tends to produce 1O 2 and •O. • Under irradiation with a long wavelength source (>475 nm), 1O 2 is mainly ROS. • Cu@CuO x /WO 3 with photo-regulated ROS generation exhibits excellent performance. Photocatalysts can absorb light and activate molecular O 2 under mild conditions, but the generation of unsuitable reactive oxygen species often limits their use in synthesizing fine chemicals. To address this issue, we disperse 1 wt% copper on tungsten trioxide (WO 3) support to create an efficient catalyst for selective oxidative coupling of aromatic amines to imines under sunlight irradiation at room temperature. Copper consists of a metallic copper core and an oxide shell. Experimental and density functional theory calculations have confirmed that Cu 2 O is the primary activation site. Under λ < 475 nm, the light excites electrons of the valence bands in Cu 2 O and WO 3 , which activate O 2 to superoxide radical •O 2 −. Then rapidly transforms into oxygen adatoms (•O) and oxygen anion radicals (•O−) species on the surface of Cu 2 O. Simultaneously, it is captured by holes in the WO 3 valence band to generate singlet oxygen (1O 2). •O bind to 1O 2 promoting the coupling reaction of amines. When λ > 475 nm, intense light absorption due to the localized surface plasmon resonance excites numerous electrons in Cu to promote the oxidative coupling with the adsorbed O 2. This study presents a promising approach towards the design of high-performance photocatalysts for solar energy conversion and environmentally-friendly oxidative organic synthesis. [ABSTRACT FROM AUTHOR]