The Mechanism of Piezocatalysis: Energy Band Theory or Screening Charge Effect?

Abstract

Piezocatalysis, a newly emerging catalysis technology that relies on the piezopotential and piezoelectric properties of the catalysts, is attracting unprecedented research enthusiasm for applications in energy conversion, organic synthesis, and environmental remediation. Despite the rapid development in the past three years, the mechanism of piezocatalysis is still under debate. A fundamental understanding of the working principles of this technology should enable the future design and optimization of piezocatalysts. Herein, we provide an overview of the two popular theories used to explain the observed piezocatalysis: energy band theory and screening charge effect. A comprehensive discussion and clarification of the differences, relevance, evidence, and contradiction of the two mechanisms are provided. Finally, challenges and perspectives for future mechanistic studies are highlighted. Hopefully, this Review can help readers gain a better understanding of piezocatalysis and enable its application in their own research.

Piezodeposition of Metal Cocatalysts for Promoted Piezocatalytic Generation of Reactive Oxygen Species and Hydrogen in Water

“…Piezocatalysis has been reported to drive two main redox reactions in water: oxygen reduction reaction to form ROS (ORR) and water splitting to generate H 2 (HER) [4a,11] . In order to characterize the piezocatalytic performance of BTO@M NPs, both ORR and HER reactions were conducted by ultrasound treatment of BTO@M dispersions with or without the presence of dissolved oxygen, respectively.…”

Piezoelectrically Mediated Reversible Addition-Fragmentation Chain Transfer Polymerization

“…It showed advances in both solution and bulk reactions where acoustic cavitation is not sufficient to promote the reaction. [9][10][11][12][13][14][15] Great efforts have been made for piezoelectrically mediated small molecular reactions, including water splitting, oxidative dye degradation, and C-C coupling. 12,[15][16][17][18][19] Piezoelectric means to activate the polymerization (piezo-polymerization) process expand the scope of piezoelectrically mediated reactions and show successes in various chemical bond formations.…”

“…The surface of ZnO plays a pivotal role in determining the piezo-reactivity. 11 After US, the color of ZnO sample (ZnO/TPMA) became gray (Figure S8a-c). We speculated that TPMA could balance the screening charges by forming TPMA cation (TPMA + ) on the ZnO surface.…”

High Efficiency Water Splitting using Ultrasound Coupled to a BaTiO3 Nanofluid

“…Piezocatalysis has often been examined by the application of ultrasound to ferroelectric materials within a liquid suspension. [ 21,23 ] There are both chemical and mechanical effects that can result from the acoustic cavitation of a liquid subjected to ultrasound. [ 37 ] These effects can be powerful tools for industrial applications where chemical effects are produced during the process of free radical production and pyrolysis as a result of the local high temperature and pressure associated with cavitation events.…”

“…The coupling of mechanical vibration to catalytic processes is a relatively new research area and has been termed piezocatalysis. [ 21 , 22 , 23 ] This provides a fascinating new approach to water splitting and environmental remediation technologies. [ 12 ] Piezocatalysis has been achieved using a variety of ferroelectric and piezoelectric materials that include lead magnesium niobate–lead titanate (PMN‐PT) single crystal, [ 24 ] lead zirconate titanate (PZT), [ 25 ] piezoelectric ZnO [ 10 , 11 , 26 ] and BaTiO 3 .…”