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

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–CuOx) were determined by highangle 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–CuOx 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–CuOx 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.

DAG (www.dagchem.com), AQ, DL, and JCC (http://photo-catalysis. org) would like to acknowledge the support from the National Science center in Poland within OPUS-13 project nr 2017/25/B/ST8/01592. SRP and JCC want to acknowledge the National Science center in Poland within Sonata Bis 5 Project No. 2015/18/E/ST5/00306 for the support. Moreover, this publication is part of a project that has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 711859 and from the financial resources for science in the years 2017- 2021 awarded for the implementation of an international co-financed project.