Mesoporous template-free gyroid-like nanostructures based on La and Mn co-doped bismuth ferrites with improved photocatalytic activity

Abstract

Template-free and gyroid-like mesoporous nanostructures of La and Mn co-doped bismuth ferrites were fabricated using a simple and low-cost double solvent sol–gel technique. By carefully controlling the amount of precursors and precisely optimizing the calcination process, a well-ordered and crystalline La and Mn co-doped BiFeO₃ gyroid-like mesoporous nanostructures network was obtained for photo-degradation applications. The substitution of Mn ions into the Fe sites resulted in a well-ordered mesoporous nanostructure with a flexibility for optical band-gap tuning up to a large extent. Catalytic photo-degradation of Congo red under visible light irradiation occurred at a much higher rate using the mesoporous nanostructures compared to pure BiFeO₃ nanoparticles. Thus, large tunability of the band gap, high activity of the mesoporous nanostructure and stability were successfully achieved. The new fabrication method presented here is the first evidence to suggest that such a well-ordered, template-free, gyroid-like mesoporous nanostructure network can be fabricated for low-cost commercial applications.