Thermal, structural and optical properties of magnetic BiFeO3 micron-particles synthesized by coprecipitation method: heterogeneous photocatalysis study under white LED irradiation

Abstract

Bismuth ferrite, BiFeO 3 (BFO) prepared via a coprecipitation method, was used as an effective photocatalyst for the degradation of methylene blue (MB) using a white light-emitting diode (LED-50 W) lamp. The as-prepared material was characterized by TGA, XRD, SEM-EDX, FTIR, and UV-vis-DRS techniques. The effects of experimental key parameters such as pH, catalyst dosage, initial dye concentration, and calcination temperature were investigated. Results showed that BFO-600 (calcined at 600 °C/3 h) was a rhombohedrally-distorted perovskite oxide with the R3c space group. The average crystal size and band gap energy for BFO-600 were found to be 24.8 nm and 2.1 eV, respectively. Under optimal operating conditions ([MB]=20 mg.L -1 , BFO-600/dye mass ratio=0.5 g.L -1 , pH=11, and 25 °C), MB/BFO-600/LED process exhibited an efficient photodegradation (up to 94.4%) within 120 min, much higher than the MB sorption process (MB/BFO-600/dark system, 69.4%) and the MB self-photolysis system (MB/ LED, 33.9%). The photocatalytic degradation of MB was found to fit well with the pseudo-first-order kinetic model. Thus, the MB photodegradation was attributed to the generation of reactive radicals such as • OH, h + , H 2 O 2 , and MB •+ via direct heterogeneous photocatalysis and mediated by MB through a self-photosensitization process of MB over BFO-600 NPs.

Hydrothermal Synthesis, Phase Analysis, and Magneto-Electronic Characterizations of Lead-Free Ferroelectric BM2+(Zn, Ca, Mg)T–BFO System

“…64 The second thermal change occurred at around 455 and 650 °C, possibly corresponding to the formation of the metal oxide phase of BiFeO 3 . 37,67 The third alteration occurs after 650 °C as a result of the bismuth oxide phase shifting and moving from a ferrous to a ferric higher oxidation state. 37 At 720 °C, the α phase of bismuth oxide is converted to the δ phase 68 as well.…”

“…37,67 The third alteration occurs after 650 °C as a result of the bismuth oxide phase shifting and moving from a ferrous to a ferric higher oxidation state. 37 At 720 °C, the α phase of bismuth oxide is converted to the δ phase 68 as well. The TG-curves exhibit total mass losses of 2.27, 1.15, and 2.07% for BZT-BFO, BCT-BFO, and BMT-BFO, respectively, up to around 1000 °C (Figure 8).…”

“…The TG-curves exhibit total mass losses of 2.27, 1.15, and 2.07% for BZT-BFO, BCT-BFO, and BMT-BFO, respectively, up to around 1000 °C (Figure 8). It is interesting to note that these hydrothermally produced samples have far lower total masses and thermal disintegration than pure BiFeO 3 perovskite, 37 which suggests that the materials are thermally stable for the applications even at high temperatures.…”

“…17,36 Moreover, optical absorbance, band gap, photocatalytic performance, and thermal stability of pure BiFeO 3 perovskite have been studied for potent application as a photocatalyst for the degradation of materials in the visible region. 37 Subsequently, it was discovered that the BiFeO 3 nanopowders had a single-phase perovskite configuration and were strongly crystalline. 17 It ought to be emphasized that the B-site replacement components synthesized from bismuth ferrite by the conventional approach belong to the identical space group, R3c or Cc, as the parent BiFeO 3 , even if distinct structural phases might develop during high-pressure synthesizing.…”

Solvothermal synthesis and characterization of monoclinic WO3 nanoplatelets: investigation of their photocatalytic performance

“…All generated reactive oxygen species (ROS) such as • OH and RhB *+ during the photocatalytic reactions suppress the recombination of the photoinduced electron-hole pairs and effectively decompose RhB into less toxic molecules or degraded or mineralized products Eq. (12)[61].RhB * + ( • OH and RhB •+ ) → degraded or mineralized products(12) …”