Domain Wall Free Polar Structure Enhanced Photodegradation Activity in Nanoscale Ferroelectric Ba_xSr_1‐xTiO₃

Abstract

Ferroelectric materials exhibit anomalous behavior due to the presence of domains and domain walls which are related to the spontaneous polarization inherent in the crystal structure. Control of ferroelectric domains and domain walls has been used to enhance device performances in ultrasound, pyroelectric detectors, and photovoltaic systems with renewed interest in nanostructuring for energy applications. It is also known that ferroelectrics including domain walls can double photocatalytic rate and increase carrier lifetime from microsecond to millisecond. However, there remains a lack of understanding on the different contributions of the domain and domain walls to photocatalytic activities. Herein it is found, by comparing samples of nanostructured BaxSr1‐xTiO3 with and without a polar domain, that the material with polar domains has a faster reaction rate (k = 0.18 min−1) than the nonpolar one (k = 0.11 min−1). It is further revealed that the observed enhanced photoactivity of perovskite ferroelectric materials stems from the inherent polarization of the domain instead of domain walls. Here, the new understanding of the underlying physics of materials with a spontaneous dipole opens a door to enhance the performance of light induced energy harvesting systems.

Chemical Solution Deposition of Single‐Phase BiFeO3 Thin Films on Transparent Substrates

“…[22] This unique single-domain-single-grain polycrystalline structure can be used for a mechanistic study of polycrystalline BiFeO 3 film in multifunctional applications without a domain wall contribution. [23] Figure 5a shows the UV-vis spectra of the three thin films with Figure 5b showing the derived Tauc-plots. From the absorption spectra, it can be seen that the BiFeO 3 thin films annealed in different atmospheres have a very close light absorption onset and show a good visible light absorption.…”

“…[ 22 ] This unique single‐domain‐single‐grain polycrystalline structure can be used for a mechanistic study of polycrystalline BiFeO 3 film in multifunctional applications without a domain wall contribution. [ 23 ]…”

Facile one-step synthesis and enhanced photocatalytic activity of a WC/ferroelectric nanocomposite

“…Therefore, there is no necessity for domain wall formation to minimize the internal stresses which are already reduced as the Ps is decreased. 66,67 Fig. 4b shows a TEM image of the WC/RbBi2Ti2NbO10 nanocomposite.…”

Ferroelectrics in Photocatalysis

“…It is found that Ba 0.8 Sr 0.2 TiO 3 with polar domain has a faster reaction rate (k = 0.18 min À 1 ) than Ba 0.2 Sr 0.8 TiO 3 with the nonpolar one (k = 0.11 min À 1 ), which disclosed that enhanced photoactivity of Ba 0.8 Sr 0.2 TiO 3 stems from the inherent polarization of the domain instead of domain walls. [47] Annealing treatment can improve the crystallinity to enhance ferroelectricity of ferroelectric semiconductors. The content of tetragonal phase of BaTiO 3 powder can be increased by annealing treatment under 1200 °C, which increased ferroelectricity than predominantly cubic BaTiO 3 .…”