Impedance spectroscopy and photocatalysis water splitting for hydrogen production with cerium modified SrBi2Ta2O9 ferroelectrics

A pure phase cerium modified bismuth layer based Aurivillius type SrBi2-xCe3x/4Ta2O9 (x = 0-0.1) ferroelectric ceramics are synthesized by solid state route. X-ray diffraction patterns are well-indexed with orthorhombic (A(21)am) according to the JCPDS card no. 49-0609. Impedance analysis revealed that the non-debye type nature and corresponding resistance-capacitance values are calculated. An existence of grain effect at high temperature is identified by modulus spectrum using Kohlrausch-Williams-Watts (KWW) function. The diffusive reflectance spectrum estimated the bandgap of cerium modified SrBi2Ta2O9 ferroelectrics and the values are increased by increasing the substitution concentration. The conduction band of these photocatalysts composed of hybridization with Ta5d + Bi6p(Ce4f)+O2p orbitals and the valence bands composed of Ta5d + Bi6s(Ce4d)+O2p orbitals. The water splitting photocatalytic activity is investigated under UV-light irradiation and indicated that these photocatalysts showed photocatalytic activity for H-2 and O-2 evolution from aqueous solutions containing sacrificial reagents (methanol and Ag+). The correlation of electrical and photocatalytic properties are explained clearly. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.