One-Step Synthesis of Cu x O y /TiO 2 Photocatalysts by Laser Pyrolysis for Selective Ethylene Production from Propionic Acid Degradation.

In an effort to produce alkenes in an energy-saving way, this study presents for the first time a photocatalytic process that allows for the obtention of ethylene with high selectivity from propionic acid (PA) degradation. To this end, TiO 2 nanoparticles (NPs) modified with copper oxides (Cu x O y /TiO 2 ) were synthetised via laser pyrolysis. The atmosphere of synthesis (He or Ar) strongly affects the morphology of photocatalysts and therefore their selectivity towards hydrocarbons (C 2 H 4 , C 2 H 6 , C 4 H 10 ) and H 2 products. Specifically, Cu x O y /TiO 2 elaborated under He environment presents highly dispersed copper species and favours the production of C 2 H 6 and H 2 . On the contrary, Cu x O y /TiO 2 synthetised under Ar involves copper oxides organised into distinct NPs of ~2 nm diameter and promotes C 2 H 4 as the major hydrocarbon product, with selectivity, i.e., C 2 H 4 /CO 2 as high as 85% versus 1% obtained with pure TiO 2 .