Suppressing Photoinduced Charge Recombination via the Lorentz Force in a Photocatalytic System

Abstract

Suppressing the recombination of photogenerated charges is one of the most important routes for enhancing the catalytic performance of semiconductor photocatalysts. In addition to the built‐in field produced by semiconductor heterostructures and the photo‐electrocatalysis realized by applying an external electrical potential to photocatalysts assembled on electrodes, other strategies are waiting to be scientifically explored and understood. In this work, a Lorentz force–assisted charge carrier separation enhancement strategy is reported to improve the photocatalytic efficiency by applying a magnetic field to a photocatalytic system. The photocatalytic efficiency can be improved by 26% just by placing a permanent magnet beneath the normal photocatalytic system without any additional power supply. The mechanism by which the Lorentz force acts oppositely on the photogenerated electrons and holes is introduced, resulting in the suppression of the photoinduced charge recombination. This work provides insights into the specific role of the Lorentz force in suppressing the recombination of electron–hole pairs in their initial photogenerated states. This suppression would increase the population of charge carriers that would subsequently be transported in the semiconductor. It is believed that this strategy based on magnetic effects will initiate a new way of thinking about photoinduced charge separation.

Magnetic and Optical Field Multi-Assisted Li-O2 Batteries with Self-Regulated Charge and Discharge

“…Photocatalytic properties of NiO/FNi under magnetic eld. According to the previous work, Lorentz force can effectively act on photocatalysis process, due to the external MF can produce opposite force on the photoelectrons and holes 19,21 . Thus, we applied NiO/FNi in the photocatalysis process with MF and without MF (MF and NMF, respectively) to understand the in uence of MF on the photocatalytic activities.…”

“…4g). Comparing with the Lorentz force of with the electric force of the effects of the magnetic eld on the charge carriers can be discussed by referring to the electric eld 19 . It can be clearly seen that a parallel and homogenous electric eld presented in the NiO nanosheets (NSs) based on the electromagnetic induction ( Fig.…”

“…However, the rapid recombination rate of the photoelectrons and holes generated in semiconductors is still a key obstacle in the photocatalyst-involved Li-O 2 battery. Conventionally, various state-of-art semiconductor heterojunctions, such as Schottky junctions, p-n junctions, and z-scheme heterostructures have been constructed to suppress the recombination of charge carriers [19][20][21][22] . Yet, the synthetic methods for heterostructures are complicated and rigorous.…”

Photocatalysis Enhanced by External Fields

“…For instance,G ao et al investigated the effect of the magnetic field on the photocatalytic performance of TiO 2 nanobelts. [11] Them agnetic-field-induced Lorentz forces separated the electrons and holes in opposite directions,w hich suppressed charge recombination in the bulk and allowed more active charge carriers to transfer to the surface.A sar esult, a2 6% improvement of photocatalytic efficiency was achieved by simply applying amagnetic field to the photocatalytic system. They also discovered that the magnetic field can induce am icro-electric potential in metals,w hich remarkably enhanced the charge separation in CdS through the fabrication of Au/CdS core-shell hybrid nanostructures.…”

“…[10] Besides,t he magnetic field induced Lorentz force and electron polarization can also provide as trong driving force to separate the photoexcited electrons and holes. [11] Nevertheless,t he effects of external fields on the band…”