Ultrasound-assisted decoration of CuOx nanoclusters on TiO2 nanoparticles for additives free photocatalytic hydrogen production and biomass valorization by selective oxidation

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 TiO<inf>2</inf> nanoparticles with nanometric sized (< 4 nm) clusters of mixed cupric and cuprous oxides. The physicochemical features of the nanocomposite (TiO<inf>2[sbnd]</inf>CuO<inf>x</inf>) 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. TiO<inf>2[sbnd]</inf>CuO<inf>x</inf> showed an enhanced and continuous capability to generate molecular hydrogen upon low power ultraviolet irradiation. The benchmark commercial TiO<inf>2</inf> P25 did not reveal any H<inf>2</inf> formation under these conditions. TiO<inf>2[sbnd]</inf>CuO<inf>x</inf> 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. © 2021