TiO2@hollow carbon spheres: a photocatalyst for hydrogen generation under visible irradiation

Abstract Hydrogen photoproduction using both hollow carbon spheres (HCSs) and titania modified hollow carbon spheres (TiO2@HCSs) has been performed under visible-light-emitting diode (LED) irradiation. The TiO2@HCSs had diameters of ca. 140-150 nm with Shell width of 20-35 nm, depending on the TiO2 loading. Raman, FTIR and XPS results indicated the formation of core-shell TiO2 modified HCSs nanostructures. Upon visible-LED irradiation, the photocatalysts exhibited efficient activity that increased from 29.1 to 267.9 µmol g-1s-1 upon increasing the TiO2 content from 2 to 5 % in the TiO2@HCSs, but a higher increase in TiO2 values led to a decrease in activity. This effect can be linked to the role of the carbon morphology on the reaction in terms of e- mobility from a VB to a CB in the catalyst.