Enhancing Charge Separation in Photocatalysts with Internal Polar Electric Fields

Abstract

The main limitations on photocatalytic efficiency are the recombination of photogenerated electrons and holes and a narrow light response. In this Minireview, we focused on photocatalytic materials with an internal polar electric field. The development and application of these compounds is one of the most efficient strategies to promote the separation of photogenerated electrons and holes, leading to high photocatalytic efficiency. This Minireview describes the fundamental operating principles of photocatalysts with a built‐in polar electric field and discusses the mechanism for polar‐electric‐field‐enhanced charge separation. We also review recent reports on photocatalytic systems using an internal polar electric field to separate photogenerated electrons and holes, focusing particularly on layer‐structure polar photocatalysts, silver silicates, and single‐crystal ZnO photocatalysts. Charge separation enhanced by an internal polar electric field provides the basis for designing new high efficiency photocatalysts.

The Role of Polarization in Photocatalysis

“…[17,28] In addition, it is an efficient strategy to either create or increase polarization by controlling the degree of phase transformation from non-ferroelectrics to ferroelectrics by thermal treatment. Fori nstance,p reparation of single crystals with growth orientation along the polarization direction will result in microscopic polarization of every polar unit, the superposition of which leads to am acroscopic polarity.…”

“…Fori nstance,p reparation of single crystals with growth orientation along the polarization direction will result in microscopic polarization of every polar unit, the superposition of which leads to am acroscopic polarity. [17,28] In addition, it is an efficient strategy to either create or increase polarization by controlling the degree of phase transformation from non-ferroelectrics to ferroelectrics by thermal treatment. [27] Thirdly,m ore effective external polarization methods need to be developed.…”

“…1.65 10 À2 ppm J À1 degradationo fSMX;40% degradation efficiency of phenol within 120 min [17] Angewandte Chemie Kurzaufsätze piezoelectric polarization field, the photoinduced e À and h + can be efficiently separated and propelled to migrate in opposite directions,b enefiting the migration of bulk charges to surface active sites for participating in various photocatalytic reactions. [19] Xue et al reported ap iezo-photocatalytic system fabricated by braiding ZnO nanowires vertically onto carbon fibers (CFs,F igure 4a).…”

The Role of Polarization in Photocatalysis

“…Secondly, precise control of the microstructure of polar photocatalysts is also a fundamental method for enhancing polarization. For instance, preparation of single crystals with growth orientation along the polarization direction will result in microscopic polarization of every polar unit, the superposition of which leads to a macroscopic polarity . In addition, it is an efficient strategy to either create or increase polarization by controlling the degree of phase transformation from non‐ferroelectrics to ferroelectrics by thermal treatment …”

Improved Photoelectric Performance of UV Photodetector Based on ZnO Nanoparticle‐Decorated BiOCl Nanosheet Arrays onto PDMS Substrate: The Heterojunction and Ti3C2Tx MXene Conduction Layer

“…[ 8,9 ] The layered structure and the as‐induced dipole can cause the efficient separation of the electron–hole pair, which can achieve enhanced photocatalytic activity and photoconductivity. [ 10,11 ] The low‐dimensional nanostructures of bismuth oxide halides, such as nanosheets, [ 12 ] nanonetworks, [ 13 ] microspheres, [ 14 ] and nanosheet arrays, [ 15 ] have been prepared and adopted as the sensitive materials for photoelectric devices. Depending on diverse preparation methods, the bandgap of BiOCl nanomaterials varies from 3.0 to 3.5 eV, making the BiOCl nanostructures promising candidates for UV‐A light detection.…”