n-La2Ti2O7/p-LaCrO3: a novel heterojunction based composite photocatalyst with enhanced photoactivity towards hydrogen production

Heterojunction based photocatalytic systems are known for their inbuilt ability to separate photogenerated charge carriers. In view of this, a series of La2Ti2O7/LaCrO3 heterojunction based photocatalysts are prepared by a solid state method and the activity is measured for the photocatalytic hydrogen evolution under visible light irradiation (lambda >= 400 nm). The prepared photocatalysts are characterized by X-ray diffraction, diffuse reflectance UV-vis spectroscopy, high resolution transmission electron microscopy, photoluminescence spectroscopy, X-ray photoelectron spectroscopy, BET surface area and photoelectrochemical measurements. The XRD, HRTEM and photoelectrochemical measurements support the formation of the heterojunction. The mechanism for the enhancement of the photoactivity is established with the help of photoelectrochemical measurements and Mulliken electronegativity concepts. The synergetic effect of both La2Ti2O7 and LaCrO3 successfully retards electron hole recombination, resulting in enhanced activity of the heterojunction system.