Charge Coupling Enhanced Photocatalytic Activity of BaTiO₃/MoO₃ Heterostructures

Abstract

In this work, we proposed an efficient heterostructure photocatalyst by integrating the ferroelectric BaTiO3 (BTO) layer with the semiconductor MoO3 layer, availing the ferroelectric polarization of BaTiO3 and high generation of photoinduced charge carriers in the MoO3 layer. The effect of MoO3 layer thickness (t MoO3 ) on the photocatalytic efficiency of the BTO/MoO3 heterostructures is found to be optimum at t MoO3 = 67 nm as t MoO3 varies from 40 to 800 nm. The BTO/MoO3 heterostructure with t MoO3 = 67 nm exhibits a high efficiency of 86% for the degradation of rhodamine B (RhB) under the exposure of UV–visible light for 60 min. The photocatalysis rate kinetics analysis reveals that the rate constant in the heterostructure is 1.7 times of pure BTO and 3.2 times of pure MoO3 films. The enhanced photocatalytic activity in the heterostructures is attributed to the electric field-driven carrier separation due to the ferroelectric polarization and the heterojunction band bending. The charge coupling effect between BaTiO3 and MoO3 is evident from the current–voltage characteristics. The maximum lattice strain in the heterostructure with t MoO3 = 67 nm as evident from X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and photoluminescence (PL) analysis further confirms the charge transfer between the layers. The degradation as well as decolorization efficiency of the BTO/MoO3 heterostructure is higher than that of pure BTO and MoO3 films. Radical trapping experiments reveal that electrons are the major contributors to the photocatalytic activity of the BTO/MoO3 heterostructure. The reusability test shows only a reduction of 5% in the efficiency of the heterostructure after five photocatalysis cycles. The heterostructure can also efficiently decompose the other dyes such as rose bengal and methyl violet. Thus, our findings prove that an efficient and reusable photocatalyst can be designed through the integration of the ferroelectrics with the semiconductor layers.

Facile Realization of Boosted Near‐Infrared‐Visible Light Driven Photocatalytic Activities of BiOF Nanoparticles through Simultaneously Exploiting Doping and Upconversion Strategy

“…In an attempt to intuitively confirm the generation of Generally, the generation of •O 2 − and •OH active species has close relation with the CB edge (i.e., E CB ) and VB edge (i.e., E VB ) of semiconductor. As previously proposed, the E CB and E VB values of a special semiconductor can be achieved with the aid of following functions: [50,51] = − + E X E E 0.5 VB e g…”

“…Generally, the generation of •O 2 − and •OH active species has close relation with the CB edge (i.e., E CB ) and VB edge (i.e., E VB ) of semiconductor. As previously proposed, the E CB and E VB values of a special semiconductor can be achieved with the aid of following functions: [50,51] www.advmatinterfaces.de herein, these parameters including X and E e are the absolute electronegativity of semiconductor and the energy of free electrons on the hydrogen scale with a fixed values of 4.5 eV, respectively. As for BiOF, the values of X and E g are 7.…”

Utilizing Upconversion Emission to Improve the Photocatalytic Performance of the BiOI Microplate: A Bifunctional Platform for Pollutant Degradation and Hydrogen Production

“…In an attempt to theoretically explain the production of • OH and • O 2 – species, the following empirical expressions are employed to estimate the edges of the conduction band ( i.e ., E CB ) and valence band ( i.e ., E VB ) of the developed compounds , where X refers to the absolute electronegativity of the semiconductor, E e , which equals to 4.5 eV, belongs to the energy of free electrons on the hydrogen scale. In terms of BiOI, its X value is 5.94, and E g equals to 1.75 eV.…”

Dynamic Internal Field Engineering in BaTiO3-TiO2 Nanostructures for Photocatalytic Dye Degradation

“…As it is well-known, ferroelectrics possess a unique property of spontaneous polarization due to a non-centrosymmetric crystal structure. A spontaneous polarization-induced electric field attributed to intrinsic dipoles in ferroelectrics can act as a driving force for promoting photoexcited charge carriers to direct transport through the material and thus suppress their recombination. − For a single component ferroelectric photocatalyst, the spontaneous polarization-induced electric field can force photoexcited electrons and holes moving in opposite directions, leading to effective separation and rapid transport of charge carriers from the bulk to the surface of the ferroelectric photocatalyst, thus enhancing photocatalytic performance. − In a ferroelectric-semiconductor heterojunction photocatalyst, charge carrier separation and transport both in the bulk and the interface can be promoted by the spontaneous polarization-induced electric field resulting in enhancement of photocatalysis. − BaTiO 3 nanocrystals have recently received great attention because of their excellent room-temperature ferroelectricity even in a dimension down to ∼5 nm and comparatively good photocatalytic activities . Yang et al reported a large enhancement of photoelectrochemical performance from 5 nm BaTiO 3 -coated TiO 2 nanowires, compared to the pristine TiO 2 nanowires.…”