Plasma spray–chemical vapor deposition of nanotextured film with α/β Bi2O3 heterostructure and photocatalytic degradation performance

Abstract

Bi2O3 film was fabricated on the aluminum foil by highly efficient and low–cost plasma spray–chemical vapor deposition (PS–CVD), using Bi powder as feedstock and plasma jet as heat source. SEM observation shows that the film presents a tree coral–like dendritic morphology which is constructed by Bi2O3 of 60–400 nm particle size. XRD and Fast Fourier transform (FFT) diagram of TEM analyses show that the film is composed of tetragonal β–Bi2O3 and a small part of monoclinic α–Bi2O3. Two band gap widths of 2.54 eV and 2.70 eV were obtained by DRS UV–Vis study, and they are well consistent with β–Bi2O3 and α–Bi2O3, respectively. TEM analysis reveals the heterojunction structure of β–Bi2O3 and α–Bi2O3. The film presents a rapid photodegradation performance of MO with good repetition rate, and the fifth–time degradation efficiency remained 80% of the first–time value. By the comparison of degradation efficiency with using radical scavengers, it is proved that the superoxide radical·O2− plays a major role, while the hydroxyl radical ·OH almost had no effect in the process of MO degradation. The above results open up the possibility of using atmospheric plasma spraying for the preparation of semiconductor nano oxide coating.