The Role of Polarization in Photocatalysis

Abstract

Semiconductor photocatalysis as a desirable technology shows great potential in environmental remediation and renewable energy generation, but its efficiency is severely restricted by the rapid recombination of charge carriers in the bulk phase and on the surface of photocatalysts. Polarization has emerged as one of the most effective strategies for addressing the above‐mentioned issues, thus effectively promoting photocatalysis. This review summarizes the recent advances on improvements of photocatalytic activity by polarization‐promoted bulk and surface charge separation. Highlighted is the recent progress in charge separation advanced by different types of polarization, such as macroscopic polarization, piezoelectric polarization, ferroelectric polarization, and surface polarization, and the related mechanisms. Finally, the strategies and challenges for polarization enhancement to further enhance charge separation and photocatalysis are discussed.

Recent progress and strategies for enhancing photocatalytic water splitting

“…In order to suppress the electron-hole recombination on surface, it is important to enhance the local polarization within the same particle to facilitate the separation of photo-excited electrons and holes. The introduction of an electric field to enhance the polarization has recently been demonstrated to be an efficient approach for improving the charge separation both in bulk and on surface of the photocatalysts [36][37][38]. Zhang's group reported a new strategy to introduce an internal electric field to Bi3O4Cl by carbon incorporation [37].…”

“…This is due to the rapid recombination of excitons to dissipate the captured solar energy to heat to environment. On the other hand, recent reports show that polarization plays an important role in the separation of these photogenerated electrons and holes from rapid recombination, which prolongs the exciton lifetime, therefore leading to enhanced photocatalytic performance [36][37][38]. Cocatalyst deposition is an effective approach to facilitate the surface reactions and suppresses the backward reactions (Fig.…”

Effect of poling on piezocatalytic removal of muti‐pollutants using BaTiO3

“…However, the input energy is different in both processes, i.e. light in case of photocatalysis and vibrations in case of piezocatalysis 7‐9 . Till now, countable articles have been reported in this direction and there is various aspects which need to be explored 5 .…”

“…light in case of photocatalysis and vibrations in case of piezocatalysis. [7][8][9] Till now, countable articles have been reported in this direction and there is various aspects which need to be explored. 5 Some of the unexplored issues are quantitative role of piezoelectric nature, role of semiconductor nature, and effectiveness of piezocatalytic for degradation of various organic pollutant such as bacterial cell, dyes, pharmaceuticals etc.…”

Ferroelectric and photocatalytic properties of Aurivillius phase Ca2Bi4Ti5O18

“…10%) due to their large band gap and rapid recombination of photoexcited electrons and holes 23 . Spontaneous polarization in a ferroelectric material can induce the internal depolarization field, which is beneficial to drive the separation of photoexcited charge carriers effectively 24 . Furthermore, as bismuth‐containing compounds, BLSFs show superior photocatalytic activity, which can be attributed to: (a) The formation of a hybridized valence band comprising of Bi 6s and O 2p states pushes up the absorption band edge, and thus leads to a reduction in the band gap; (b) The dispersed nature of hybridized valence bands enhances the mobility of the photoexcited holes, and thus facilitates the photodegradation process 25,26 .…”