The prospect of piezoelectric effect in persulfate-based advanced oxidation processes

Compared to traditional Fenton technology, persulfate-based advanced oxidation processes (PS-AOPs) represent an emerging method for eliminating organic pollutants in water. However, the existing PS activation methods, such as ultraviolet (UV), microwave, heat, and transition metal activation, require large energy consumption or continuous chemical reagent input, limiting the practical application of PS-AOPs. Piezoelectric activation of PS involves using the piezoelectric effect of materials to initiate PS and generate a variety of active species. The piezoelectric effect refers to the phenomenon that non-centrosymmetric crystal materials display polarization when subjected to a mechanical stress or pressure. This interaction enables the effective conversion of environmental mechanical energy, such as wind, tides, water flow, sound, and atmospheric forces, into electrical energy. It has been reported that the local charges generated by the piezoelectric effect of the material assist in breaking O–O bond in PS, thereby facilitating PS activation. In this review, we primarily discuss the application of the piezoelectric effect of materials in PS-AOPs, elucidating the significant potential of piezoelectric/PS-AOPs and emphasizing their broad prospects as integral components of AOPs. Firstly, we summarize the basic principle of piezoelectric/PS-AOPs. Specifically, when piezoelectric material is excited by an external force, it generates a local charge, leading to the breaking of O–O bond in PS through an electron transfer reaction. This process results in the formation of various active substances (such as HO•, SO4•–) for pollutant removal. Next, we introduce common piezoelectric materials and their modification methods. BaTiO3 stands out as the most extensively studied piezoelectric catalyst, while other materials like ZnO, MoS2, and BiVO4, have emerged as viable competitors for piezoelectric activation of PS. Modified technologies such as morphology control, noble metal loading, single atom anchoring, element doping, defect engineering, and hybrid construction can optimize the structure and properties of the catalyst, thereby enhancing its piezoelectric response and catalytic activity during PS activation. In addition, we also explore the mechanical force sources and potential application scenarios of piezoelectric/PS-AOPs. Currently, the external forces have been used into piezoelectric catalytic activation of PS including ultrasonic, stirring and water flow. The application scenarios of piezoelectric/PS-AOPs mainly involve pollutant degradation and wastewater resource utilization. Lastly, we discuss the prospects of piezoelectric/PS-AOPs, including their potential application in urban pipeline drainage systems in the future. In summary, piezo-catalysis has emerged as a promising method for PS activation, holding great potential for environmental remediation and wastewater resource utilization. Unlike traditional energy-intensive PS activation methods, this technology harnesses weak mechanical forces existing in nature, making it a transformative force in the field of AOPs. Through this review, we aim to offer valuable suggestions for the more efficient application of piezoelectric/PS-AOPs in wastewater treatment and environmental remediation, thereby promoting the advancement of this emerging field. © 2024 Chinese Academy of Sciences. All rights reserved.