Study of NiFe2O4 nanoparticles optical properties by a six-flux radiation model towards the photocatalytic hydrogen production

At present, synthesis of visible-light active materials for hydrogen production through water splitting has become one of the most important challenges in photocatalysis. Of equal importance, photocatalyst optical properties are essential information in order to determine reaction kinetics involved in water splitting. Transition metals spinel ferrites MFe2O4 exhibit remarkable activity under visible light for this reaction. However, their optical properties have not been fully determined in photocatalytic kinetic studies. In this research, synthesized and commercial NiFe2O4 nanoparticles were compared. NiFe2O4 was synthesized by the Pechini method and both materials were studied: structural, textural and optical characterization was performed through XRD, TEM, TGA, BET surface area and UV/Vis spectroscopy and photocatalytic evaluation was performed for hydrogen production. NiFe2O4 optical properties were determined by UV/Vis spectroscopy and using a simplified theoretical model for the Radiative Transfer Equation (RTE) called Six-Flux Model (SFM). All performed characterizations and obtained coefficients for the ferrites were compared finding differences between absorption and scattering coefficients, which were attributed to the porosity of the synthesized ferrite.