Preparation and characterization of porous iron oxide dendrites for photocatalytic application

Abstract

In the present work, the role of the nonionic polymeric surfactant, pluronic P123 on the formation of porous iron oxide dendrite structures are explored. The iron oxide samples were prepared at different hydrothermal treatment time of 6, 12, 24 and 48 h using potassium ferricyanide as the raw material in presence and in absence of surfactant. The samples were characterized by XRD, FTIR, SEM, HRTEM, DRS, PL, BET-BJH and XPS analyses. The iron oxide dendrites prepared using surfactant by the hydrothermal treatment time of 12 h at 180 °C (PK12), show high photocatalytic degradation ability of 87 % towards methylene blue under visible light for a less amount of catalyst loading of 10 mg. Whereas the iron oxide prepared in absence of surfactant under similar conditions (K12) shows the incomplete phase formation with mixed dendrite and bulk cubic structures, exhibiting only 47 % of degradation towards methylene blue for the similar amount of catalyst loading. The sample PK12 exhibits a degradation rate constant value of 4.25 × 10−4 s−1 which was 2.3 times higher than the sample K12 with a rate constant value of 1.88 × 10−4 s−1. The enhanced catalytic performance of the sample PK12 prepared using surfactant are attributed to its bimodal porous nature, stronger visible light absorbance, and lower recombination of photo-generated electron-hole pairs. XPS results substantiates that significant oxygen vacancies in as prepared photocatalyst, facilitates the superior photocatalytic performance. The relative peak area ratio between Olattice/Ovac was found to be lower in PK12 (0.98) than in K12 (1.82). This indicates the sample PK12 have more oxygen vacancies than the sample K12. After the photocatalytic degradation, iron oxide was retrieved by simple sedimentation process and reused for four times without any considerable decrease in efficiency, proving its economic viability for large scale applications. Magnetic studies shows a coercivity of 1582 Oe and 1162 Oe for the samples PK12 and K12, respectively.