Synthesis and investigation of photoactive sillenite bi24ga2o39 and brownmillerite ba2in2o5 for energy and environmental applications

Abstract

newlineWater and air pollution are some of the major issues demanding ourattention towards remediation of environment. Numerous materials havealready been explored for photocatalytic treatment of contaminated water as well as H2 generation. Role of sulfide, halides, carbon-based materials and metal alloys/ions are more pronounced in the photocatalytic based applications, but their efficiency is marred by features such as wide band gap, low stability, safety measures, rare availability and expensive. On the other hand, oxides offer advantages such as higher stability in atmosphere, ease to handle/storage and economical affordability. The present work intensively newlineexplores oxide based visible light driven photoactive materials for the energy newlineand environmental remediation. We present our work on oxide-based newlinephotocatalysts, sillenite and brownmillerite structured materials for newlinephotocatalytic applications. The non-stoichiometric form of sillenite newlinesynthesized here is that of Bi24M2O39. Bi present in the structure has newlineelectrostatically active 6s2 lone electron pairs which induces polarization to newlineavert the recombination of photo generated electron hole pairs significantly newlinepromoting higher photocatalytic behavior. With this beneficial nature, newlinesillenite materials are one of the preferred materials to degrade persistent newlineaqueous pollutants. In the interim, brownmillerite materials are derived from newlinethe perovskite structure. They possess one-sixth ordered oxygen vacancies in newlinealternating layers along the [110] direction of cubic perovskite. Such specific newlineoxygen deficient structures lead to enhanced adsorption sites and sometimes newlineact as trap sites, preventing recombination and improving the photocatalytic newlineactivity. In addition, these materials have narrow band gaps and wide newlineabsorption in the visible region of solar spectrum. Sillenite structured newlineBi24Ga2O39 (BGO) and brownmillerite structured Ba2In2O5 (BIO) were newlineselected for investigation and realization of its photoactive properties. The newlinesamples were synthesized through simple and inexpensive techniques and newlinetheir properties were analyzed through appropriate characterization newlinetechniques.Gallium based sillenite BGO, has been successfully synthesized newlinethrough simple methods such as hydrothermal route (HY) and solid-state newlinereaction (SS). X-Ray diffraction (XRD) data of BGO samples confirm the newlinepresence of single phase and Rietveld refinement of same revealed the unit newlinecell parameters for both samples newline newline