Sol-gel synthesis of nanoporous LaFeO3 powders for solar applications

Abstract

In the present study, we report on the synthesis of nano-porous perovskite-type lanthanum iron oxide, LaFeO3, using the ascorbic-acid assisted sol-gel method. The as-synthesized powders are characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), electron energy-loss spectroscopy (EELS), and ultra-violet visible (UV–Vis) spectrophotometry. Experimental results are systematically discussed by Density Functional Theory modeling analysis. Our XRD findings show that the as-synthesized powders have an excellent crystallinity. These powders are found to be composed of particles around 60 nm in size, as revealed by TEM results, inside which there exist a high density of pores. Each nanoparticle exhibits a good chemical homogeneity as determined from core-loss EELS mapping analysis. Our low-loss EELS analysis, in addition, shows that the optical bandgap as measured on a single particle is close to 2.38 eV, which is larger than that of its bulk counterpart (2.1 eV). This result is also confirmed with the help of UV–Vis McLean analysis on a macroscopic scale, where the inter-pore spacing (22 nm) is found to be responsible for the observed increase in the bandgap. We believe that this increase in the bandgap, combined with the fine inter-particles porosity, make our as-synthesize nanoporous LaFeO3 powders a promising candidate for solar photocatalytic activities.