Nanoreactor based enhancement of photocatalysis with Co0.7Zn0.3Fe2O4@SrTiO3 core-shell nanocomposites

Abstract

The activity of nanocatalysts on photocatalysis needs to be comprehensively understood based on different parameters affecting its performance. Also, magnetically recoverable nanocatalysts combining decent magnetization, effective adsorption and efficient photocatalysis is a necessity for future water purification schemes. In this context, the synthesis of core-shell nanostructures and understanding of nanostructure driven catalytic activity gains huge significance. Influence of pore hierarchy on the adsorption and photocatalytic efficiency is an emerging topic of investigation. Here, the Co0.7Zn0.3Fe2O4-SrTiO3 nanocomposites (CZFO@STO) were synthesized by hydrothermal route. TEM images confirmed core-shell morphology. CZFO@STO exhibited enhanced macroporosity as evaluated by BET analysis. The XPS studies indicated formation of a straddling type heterojunction extending the optical activity of STO to visible region. The CZFO@STO exhibited a high visible light photocatalytic activity rate constant of 5.08 × 10−1 min−1 on Congo Red. The origin of the enhanced activity attributed to nanostructuring as indicated by experiment varying dye concentration. The adsorption of Congo Red and Methylene Blue in single and binary system onto CZFO@STO was explained based on Langmuir isotherm and pseudo-second-order model. As a photocatalyst, the CZFO@STO are magnetically recoverable and exhibited good recycling properties even in binary impurity system. An understanding of the enhanced catalytic activity is developed based on the adsorption capacity of dyes, scheme of adsorption, hierarchy of pores and advantages offered by core-shell nanostructuring including enrichment by shell and formation of a nanoreactor. The study could catapult bigger role for core-shell nanocomposites in adsorption driven fields of applications like catalysis, gas capture, sensing and energy storage.