Improved photocatalytic performance of gradient reduced TiO2 ceramics with aligned pore channels
Hanyu Gong, Lu Wang, Kechao Zhou, Dou Zhang, Yan Zhang, Vana Adamaki, Aleksandrs Sergejevs, Chris Bowen
Abstract
Magnéli, a fascinating sub-stoichiometric titanium oxide phase that contains oxygen vacancies of TiO2, is proposed as a potential photo-electrode for photocatalysis due to its high conductivity and photoelectric conversion efficiency. In this work, partially reduced porous TiO2 ceramics with a graded reduction profile and an aligned pore structure were prepared by carbo-thermal reduction of freeze-cast TiO2 with a range of porosities from 10 to 30 vol.%. AC conductivity evaluation revealed that the oxygen vacancies that exist in Magnéli lead to a relatively high AC conductivity of ∼10 S/m at 1 kHz, as compared to that of the stoichiometric porous TiO2. A maximum photocurrent density and incident photon-to-current efficiency (IPCE) of 9.14 mA/cm2 and 40.52% respectively were achieved from the gradient porous Magnéli with a porosity of 30 vol.%.