Abstract

The herein presented ultrasound-assisted ultra-wet (US-UWet) impregnation synthetic approach was followed in order to avoid the drawbacks of the conventional wet impregnation synthesis. The goal was to homogeneously decorate the surface of the TiO₂ nanoparticles with nanometric sized (< 4 nm) clusters of mixed cupric and cuprous oxides. The physicochemical features of the nanocomposite (TiO₂-CuO_x) were determined by high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM), high-resolution transmission electron microscopy (HR-TEM), energy dispersive X‑ray (EDX), X ray photoelectron spectroscopy (XPS), powder X‑ray diffraction (XRD), and Diffuse reflectance (DR) spectroscopy. TiO₂-CuO_x showed an enhanced and continuous capability to generate molecular hydrogen upon low power ultraviolet irradiation. The benchmark commercial TiO₂ P25 did not reveal any H₂ formation under these conditions. TiO₂-CuO_x presented also a high efficiency for the additives-free selective partial oxidation of two well established biomass derived model platform chemicals/​building blocks, 5 hydroxymethylfurfural (HMF) and benzyl alcohol (BnOH) to the value-added chemicals 2,5‑diformylfuran (DFF) and benzyl aldehyde (PhCHO), respectively. The nanocomposite showed higher DFF and PhCHO yield compared to P25.