Highly mesoporous α-Fe₂O₃nanostructures: preparation, characterization and improved photocatalytic performance towards Rhodamine B (RhB)

Abstract

Single-crystalline porous hematite nanorods and spindle-like nanostructures were successfully synthesized by a low temperature reflux condensation method. Two different iron sources, namely, FeCl3·6H2O and Fe(NO3)3·9H2O, were hydrolyzed in the presence of urea to selectively prepare nanorods and spindle-like nanostructures. Initially, the akagenite phase was obtained by refluxing the precursor for 12 h and then the as-prepared akagenite nanostructures were transformed to porous hematite nanostructures upon calcination at 300 °C for 1 h. The shape and the aspect ratio of the 12 h refluxed sample was retained even after calcination and this shows the topotactic transformation of the nanostructure. TEM and HRTEM investigations have shown the porous nature of the prepared sample. Brunauer–Emmett–Teller and Barret–Joyner–Halenda measurements have shown a large surface area and distribution of mesopores in the nanorods sample. The photocatalytic activity of the prepared nanostructures towards RhB has reflected this variation in the pore size distribution and specific surface area, by showing a higher activity for the nanorods sample. Magnetic studies by VSM have shown a weak ferromagnetic behaviour in both the samples due to shape anisotropy.

Development of novel α-Fe2O3/NiTiO3 heterojunction nanofibers material with enhanced visible-light photocatalytic performance

“…2b), which was in accordance with the result of previous literature [24]. The origin of these pores could be assigned to the dehydroxylation of FeOOH to form a-Fe 2 O 3 [27]. Images …”

Synthesis, morphology, microstructure and magnetic properties of hematite submicron particles

“…The existence of the hysteresis loop below T M (AF region) shows that uncompensated spins exist at the surface of particles. The influence of the shape and microstructure of the particles on the coercivity is well known and an increase of the coercivity with increasing aspect ratio has been reported [26][27][28][29][30][31][32][33][34][39][40][41][42][43]47,55,78]. For example, in nanosized Fe, increases of aspect ratio by a factor 5 (from one to five) increases coercivity ten times [78].…”

A novel thermal decomposition approach for the synthesis of silica-iron oxide core–shell nanoparticles

“…Hematite (␣-Fe 2 O 3 ), a narrow band gap semiconductor, has been used as a catalyst for the photodegradation reactions due to its photoelectrochemical stability in aqueous solution [31,32,[58][59][60]. Since the magnetic silica-iron oxide core-shell nanoparticles (SF-1 and SF-2) after calcination at 750 • C contain ␣-Fe 2 O 3 nanoparticles, they were used for the photocatalytic degradation of RhB.…”

“…Iron oxide nanoparticles have been known for their catalytic activity against the photo degradation of organic dyes which cause air and water pollution [31]. The rate of degradation of the dyes is usually slow, in sunlight, in the absence of a catalyst.…”