Citric acid as complexing agent in synthesis of mesoporous strontium titanate via neutral-templated self-assembly sol–gel combustion method

Abstract

In the present work, mesoporous SrTiO3 (MST) nanoparticles were synthesized via a self-assembly sol–gel combustion method using a commercial non-ionic triblock copolymer (Pluronic P123) as a structure-directing agent. The effect of adding citric acid as a metal-ion complexing agent on the formation of crystalline SrTiO3 with enhanced surface area and mesoporosity was investigated. Simultaneous thermal analysis and powder X-ray diffraction indicated that the citric acid added to the synthesis mixture enhances the formation of high-purity perovskite SrTiO3 crystallites. The MST synthesized in the presence of both Pluronic P123 and citric acid (MST-C) possessed higher surface area (41.5 m2 g−1) and larger pore volume (0.20 cm3 g−1) than materials synthesized without the addition of either citric acid or the templating agent. The SrTiO3 crystals of MST-C shared edges and corners to form globular agglomerates with accessible mesopores revealed by electron microscopy. Results suggest that the mesoporous structure is generated via a hard template route.