Abstract
In this work, we provide new insights into the design of Ti@TiO 2 photocatalyst with enhanced photothermal activity in the process of glycerol reforming. Ti@TiO 2 nanoparticles have been obtained by sonohydrothermal treatment of titanium metal nanoparticles in pure water. Variation of sonohydrothermal temperature allows controlling nanocrystalline TiO 2 shell on Ti 0 surface. At 100 < T < 150°C formation of TiO 2 NPs occurs mostly by crystallization of Ti(IV) amorphous species and oxidation of titanium suboxide Ti 3 O presented at the surface of Ti 0 nanoparticles. At T > 150°C, TiO 2 is also formed by oxidation of Ti 0 with overheated water. Kinetic study highlights the importance of TiO 2 nanocrystalline shell for H 2 generation. Electrochemical impedance spectroscopy points out more efficient electron transfer for Ti@TiO 2 nanoparticles in correlation with photocatalytic data. The apparent activation energy, E a = (25–31) ± 5 kJ·mol −1 , assumes that photothermal effect arises from diffusion of glycerol oxidation intermediates or from water dynamics at the surface of catalyst. Under the heating, photocatalytic H 2 emission is observed even in pure water.