Effect of Calcination Temperature on the Photocatalytic H2 Evolution of Bronze Phase Monoclinic TiO2(B) Nanosheets

In this work, we have successfully fabricated bronze phase monoclinic TiO2 (B) nanosheets from TiCl3 under hydrothermal conditions. The fabricated samples were calcined at different annealing temperature (100, 200, 300, 400 and 500 oC) to select optimum temperature under UV light irradiation for the efficient photocatalytic water splitting. Different techniques were used for the characterization of fabricated photocatalysts. Interestingly, the sample calcined at 400 oC delivered optimum H2 evolution from water which is attributed to the relatively high surface area and effective charge separation. The characteristic anisotropic nature of TiO2(B) plays very crucial role in charge separation which is evident from photoluminescence spectra, steady-state surface photovoltage spectra, and produced hydroxyl radical amount. It has been concluded that optimum annealing temperature generally introduces charge trapping centres which help in the separation of excite charges for improved photocatalytic activity. However, high temperature results in particles aggregation to reduce the surface area and hence retards the photocatalytic efficiency. This work will direct future research to fabricate materials at optimized temperature for the improved photocatalytic activities.