Harvesting the Vibration Energy of BiFeO₃ Nanosheets for Hydrogen Evolution

Abstract

In this study, mechanical vibration is used for hydrogen generation and decomposition of dye molecules, with the help of BiFeO3 (BFO) square nanosheets. A high hydrogen production rate of ≈124.1 μmol g−1 is achieved under mechanical vibration (100 W) for 1 h at the resonant frequency of the BFO nanosheets. The decomposition ratio of Rhodamine B dye reaches up to ≈94.1 % after mechanical vibration of the BFO catalyst for 50 min. The vibration‐induced catalysis of the BFO square nanosheets may be attributed to the piezocatalytic properties of BFO and the high specific surface area of the nanosheets. The uncompensated piezoelectric charges on the surfaces of BFO nanosheets induced by mechanical vibration result in a built‐in electric field across the nanosheets. Unlike a photocatalyst for water splitting, which requires a proper band edge position for hydrogen evolution, such a requirement is not needed in piezocatalytic water splitting, where the band tilting under the induced piezoelectric field will make the conduction band of BFO more negative than the H2/H2O redox potential (0 V) for hydrogen generation.

Piezocatalysis and Piezo‐Photocatalysis: Catalysts Classification and Modification Strategy, Reaction Mechanism, and Practical Application

“…[ 102 ] Bi 2 O 2 (OH)(NO 3 ) [ 14 ] is a polar photocatalyst with sillen‐related crystal structure, and the piezocatalytic • OH generation and degradation activity of ultrathin Bi 2 O 2 (OH)(NO 3 ) nanosheets and bulk Bi 2 O 2 (OH)(NO 3 ) were demonstrated. For the well‐known photocatalysts BiOCl and BiFeO 3 , [ 16,63 ] the piezocatalytic H 2 generation of BiOCl and BiFeO 3 was detected (Figure 7g,h). The positive and negative charges on the BiOCl and BiFeO 3 monodisperse nanoplates acted as a powerful electrode which attracted the dissociated H + from H 2 O for yielding H 2 with the consumption of electron donor (Figure 7i).…”

“…Reproduced with permission. [63] Copyright 2019, Wiley-VCH. As discussed above, polarization increased by the crystal growth along specific direction can generate greater piezopotential for benefiting the catalysis of ZnO; it also works for BaTiO 3 NWs or nanocubes.…”

Reactive Oxygenated Species Generated on Iodide‐Doped BiVO4/BaTiO3 Heterostructures with Ag/Cu Nanoparticles by Coupled Piezophototronic Effect and Plasmonic Excitation

“…[ 21 ] By tuning the composition and the structure of piezoelectric materials, and properties of the electrolytes, it is possible to tune the extent of the polarization‐induced depolarization field, and in turn, the production and composition of the ROS being formed. Common piezoelectric semiconductors such as MoS 2 , [ 22 ] BaTiO 3 , [ 23 ] and BiFeO 3 [ 24 ] have been shown to produce ROS under a mechanical strain stimulus, and the ROS have been used for tentative applications in wastewater treatment [ 25 ] and tumor therapy. [ 3a ] In general, mechanically‐induced redox catalysis has been studied, called as mechanoredox catalysis or piezocatalysis, using piezoelectric materials for organic synthesis, [ 26 ] sonotherapy, [ 3c ] and water splitting.…”

Flammable gases produced by TiO2 nanoparticles under magnetic stirring in water

“…In recent years, there has been a growing interest in utilizing mechanical energy as a clean energy for more applications. For instance, piezoelectric nanomaterials, especially those of one-and two-dimensions, undergo considerable deformation under vibrations with piezopotentials generated across them [1], which subsequently induce such redox reactions as degradation of organic pollutants [2][3][4][5][6] and hydrogen production [7][8][9]. A technology known as piezocatalysis has thus emerged, which aims to harvest mechanical energy in ambient environments through piezoelectric nanomaterials for chemical reactions and has been extensively investigated [10,11].…”