A Type‐II Heterostructure with a KBiFe₂O₅ Brownmillerite Core and a ZnO Nanoparticle Shell for Enhanced Optoelectronic Performance

Abstract

We formed a core-shell heterostructure with a brownmillerite multiferroic KBiFe 2 O 5 core and a wurtzite ZnO nanoparticle shell by sol-gel technique. The KBiFe 2 O 5 behaves as a p-type semiconductor when coupled with n-type ZnO nanoparticles. The heterostructure and the individual materials were characterized by various microscopy and spectroscopy techniques. From scanning tunneling spectroscopy and correspondingly the density of states spectra, we locate the band edges to infer the nature of the individual semiconductors. The energy level diagram of the heterostructure shows the type-II band alignment at the interface, which facilitates charge separation upon illumination. In consequence, the heterostructure reveals a better degradation yield (82.5 %) of methylene blue under sunlight and photovoltaic response compared to the individual semiconductors. The ZnO nanoparticle shell plays an important role in enhancing catalytically active sites including photogenerated charge carriers to disintegrate chemical disposal from the wastewater. All oxide heterostructures thus provide a perfect combination to maximize solar light absorption, including improved charge carrier separation at the junction by appropriate core-shell interface band alignment.

MXene as a Superior Charge-Transport Layer in an MXene–BiFeO3–ZnO Nanocomposite for Photocatalytic Disintegration of Antacids

“…While the positive energy value denotes the CB position, the negative value represents the VB position. Seemingly, BZ heterostructures result in type-II staggered heterojunctions, which are potentially important for photocatalysts, photovoltaics, and other optoelectronic applications. − The band diagram across the junctions could be drawn precisely with energies as actually encountered by electrons and holes in an optoelectronic device. The observed energy offset of the BZ heterostructure may thus facilitate charge separation upon illumination.…”