Synthesis and Characterization of Reduced Band Gap Ferroelectric Nidoped (Ba0.85Ca0.15Zr0.1Ti0.9-X Nix) O3 –Ag2O Composite for Visible Lightdriven Photocatalysis

Abstract

Ferroelectric materials are investigated for the photocatalytic applications due to their internal polarization which provides efficient charge carrier separation and reduces the recombination rate. However, their efficiency is low because of their wide band gap(>3eV), which limits its absorbance in visible region. To overcome this issue, several ways have been developed like designing a reduced band gap ferroelectric material by doping transition metal at B-site of perovskite structure. Barium calcium zirconate titanate (BCZT) has excellent ferroelectric properties, but due to its high optical bandgap (~3.12 eV), absorption in visible region is restricted. So, to make it a visible light active photocatalyst, its band gap should be modified with the doping of transition metal (Ni) at Tisite with retention in ferroelectricity. Also, formation of heterostructure with low band gap semiconductor (Ag2O) with matching band potential can help to facilitate efficient charge carrier generation and reducing their recombination rate. This work deals with the synthesis of phase pure reduced band gap Ni-doped BCZT [(Ba0.85Ca0.15)(Zr0.1NixTi0.9-x) O3] (x=0.01-0.05) by solid-state route. The samples were characterized by XRD, FESEM, P-E loop, UV-Vis and impedance spectroscopy. The photocatalytic activity was performed through degradation of RhB dye under the irradiation of UV-Visible lamp and it was observed that pure BCZT is degrading ~7% of RhB dye in 150 minutes but with Ni doping the degradation increased up to ~32% in 150 minutes by BCZTNi0.01 compositions. To get smaller particle size, the best composition i.e., BCZTNi0.01 was also synthesized by combustion route and heterostructure composite was formed with Ag2O (75:25, 50:50 and 25:75) through precipitation method. The formed composite {BCZTNi0.01-Ag2O (50:50)} mineralised RhB dye in just 25 minutes. This excellent photocatalytic activity can be attributed to the synergetic effect of ferroelectricity and visible light activity of the formed heterostructure between reduced band gap BCZTNi and Ag2O.