Synthesis, characterization and photocatalytic evaluation of strontium ferrites towards H2 production by water splitting under visible light irradiation

Renewable hydrogen production demands materials with adequate structural, textural, optical and photocatalytic properties for the splitting of the water molecule under visible light irradiation. In this research, the spinel, hexagonal and orthorhombic strontium ferrite crystalline phases (SrFe2O4, SrFe12O19 and Sr7Fe10O22) were synthesized, characterized and photocatalytically evaluated towards H2 production through water splitting. These materials show attractive features such as being inexpensive, environmentally friendly and present visible spectrum band gaps (1.5-2.5 eV). Strontium ferrites were synthesized from nitrate precursors by the modified Pechini's method at high temperatures. Characterization consisted in XRD, SEM, BET surface area, and UV-Vis spectroscopy. XRD results indicate the presence of pure phases with a crystal size of 15, 30 and 30 nm for the spinel, hexagonal and orthorhombic phases, while BET surface area were 18, 14 and 4 m2/g, respectively. Photocatalytic evaluation resulted in the spinel phase being the most active material producing 730 μmol H2/g h.