Dye Degradation Activity and Stability of Perovskite-Type LaCoO<SUB>3&minus;<I>x</I></SUB> (<I>x</I>=0&sim;0.075)

Abstract

Perovskite-type LaCoO 3Àx (x ¼ 0$0:075) porous powder was synthesized via citrate sol-gel method. With calcination temperature increasing, its crystal structure changed from LaCoO 3 to LaCoO 2:925 with the increase in oxygen vacancy. The synthesized LaCoO 3Àx contains a large amount of adsorbed oxygen on its surface due to the existence of oxygen vacancy to some extent. Dye degradation activity of LaCoO 3Àx in methyl orange solution was investigated both under the visible light irradiation (>400 nm) and in the dark. LaCoO 3Àx exhibited dye degradation activity in the dark when being preserved in methyl orange solution for a long time caused by the reducibility of Co 3þ in LaCoO 3Àx , and then dye molecule was oxidized gradually and slowly. The degradation rate was improved under the visible light due to the optical property of LaCoO 3Àx in visible light region. After degradation, methyl orange molecule may be decomposed to acetate group in a small amount. After use for a long time, some Co 3þ was reduced to Co 2þ accompanied by the formation of oxygen vacancy, and then LaCoO 3 transformed to LaCoO 2:925 gradually. For LaCoO 3Àx calcined at 800 C, LaCoO 3Àx perovskite skeleton structure was stable, and can be reused in recycle dye degradation.

La0.6Sr0.4Co0.8Ga0.2O3‐δ (LSCG) hollow fiber membrane reactor: Partial oxidation of methane at medium temperature

“…55 This leads to enhanced electronic activity due to the hydrocarbon degradation taking place, whereby the strongly reducible nature of Co 31 will induce transformation to Co 21 which has stable half-filled orbits containing stable electron distribution of t 2g 5 e g 2 . 60 As can be observed from Figure 9 and Table 1, upon exposure to the reducing gases, the Co2p 3/2 peak appear to shift to lower binding energies, indicating the presence of Co have also been observed by Petunchi and Lombardo during reduction of LaCoO 3 under H 2 . 62 The XPS data correlate with the EDX data shown in Figure 7, and gives greater insight on the elemental existence of the Co-species on the membrane surface.…”

Degradation of bisphenol-a using a sonophoto Fenton-like hybrid process over a LaFeO$_{3}$ perovskite catalyst and a comparison of its activity with that of a TiO$_{2}$ photocatalyst

“…This result may be due to crystal growth and particle agglomeration. 43 The external surface area of the LaFeO 3 -500 perovskite used increased from 9.4 m 2 /g to 14.2 m 2 /g. This result may be due to the reduction of catalyst pore size during the sonication in the oxidation process.…”

A Review on Visible Light Active Perovskite-Based Photocatalysts

“…DFT studies show that NaBiO 3 has a strong band dispersion arising from Na 3s and O 2p hybridized orbitals, which contributes to the higher photocatalytic activity [112]. LaCoO 3 has a band gap value of 2.7 eV and oxygen deficient LaCoO 3 (LaCoO 3-δ ) has been studied for MO degradation (>400 nm) [116].…”