Piezocatalytic Activity Research Articles

Atmosphere-driven metal-support synergy in ZnO/Au catalysts for efficient piezo-catalytic hydrogen evolution

Piezo-catalysis, which leverages mechanical energy to drive chemical reactions, is emerging as a promising method for sustainable energy production. While the enhancement of piezo-catalytic performance through metal-support interactions is well-documented, the critical influence of the synthesis atmosphere during metal-loaded piezo-catalyst preparation has been a notable gap in the field. To this end, we systematically investigate how different atmospheric conditions during the synthesis of catalysts—without gas flow or with Ar, N2 and O2—affect metal dispersion, oxidation states, piezo-carrier dynamics, and electronic structure, and subsequently shape the metal-support interactions and piezo-catalytic activity. ZnO/Au, with Au deposited on ZnO, is selected as the model system, and hydrogen evolution reaction is used as the probe reaction. Our results demonstrate that an oxygen-enriched atmosphere significantly enhances the metal-support interactions, achieving an ultrahigh net hydrogen yield of 16.5 mmol·g–1·h–1 on ZnO/Au, a 3.58-fold increase over pristine ZnO. Specifically, the performance improvements substantially surpass those synthesized under other atmospheric conditions. Conversely, exposure to CO2 transforms the ZnO support into ZnCO3, adversely affecting its catalytic activity. These findings reveal the crucial impact of synthesis conditions on piezo-catalyst performance and thereby open new avenues for optimizing catalyst systems for enhanced sustainability.

Efficient enhancement of piezo-catalytic activity of BaTiO3-based piezoelectric ceramics via phase boundary engineering

Piezoelectric catalysis stemmed from lead-free piezoelectric ceramics is an emerging catalytic technology applied extensively in degradation of organic pollutants due to its low energy consumption and non-pollution. However, the dissatisfied catalytic efficiency of lead-free piezoelectric ceramics has constrained their further development and application. Herein, we employ ion doping to modulate the phase boundary construction of BaTiO3-based piezoelectric ceramics (BaTi(1-x)(Zr1/3Sn1/3Hf1/3)xO3, BTZSH-x), and the degradation performances of organic dyes are explored to illuminate the piezo-catalytic mechanism. The ion doping alters the phase boundary of BaTiO3 ceramics and a two-phase coexistence of rhombohedral-orthorhombic is achieved at room temperature in BTZSH-0.04 ceramic. Consequently, the BTZSH-0.04 ceramic exhibits an excellent degradation efficiency of rhodamine B with 97.27% in 60min and a high reaction rate constant of 0.056 min−1 under ultrasonication which is 7.4 times more than that of pristine BaTiO3. This work provides an advisable policy for constructing environmental-friendly piezoelectric materials with glorious piezo-catalytic activity.

Dual fillers ZrO2/BaTiO3 incorporated PVDF-HFP nanofiber composite for enhanced piezoelectric energy harvesting and piezo catalytic reduction of hexavalent chromium

A novel Piezoelectric Nanogenerator (PENG) was designed and fabricated using electrospun nanocomposite fibers of Poly(vinylidene fluoride)-co-hexafluoropropylene (PVDF-HFP) with Barium Titanate (BaTiO3) and Zirconium Oxide (ZrO2) as dual fillers. ZrO2 fillers were incorporated at varying loadings into the PVDF-HFP polymer matrix to produce the PBZ nanocomposite fibers. The synergistic effect of BaTiO3 and ZrO2 significantly enhanced the piezoelectric performance of the resulting PBZ composite. The dual fillers also induced the nucleation of the β-phase in the nanofiber composite, which further improved its piezoelectric properties. This enhancement rendered the composite highly effective for dual applications: energy harvesting and the piezocatalytic reduction of hexavalent chromium (Cr(VI)). The PENG exhibited an open-circuit voltage of 6.3 V, a current of 0.67 µA, and a power density of 30.91 mW/m². The device was also tested in real-world scenarios, such as finger tapping and shoe sole applications, additionally it successfully powered up to five LEDs and charged a 1–2.2 μF capacitor to approximately 1–3 V under an external load of 1 N at 2 Hz. In addition to energy harvesting, the PBZ nanofibers demonstrated remarkable piezocatalytic activity by converting highly toxic Cr(VI) to Cr(III), which is biologically essential in trace amounts. The PBZ nanofiber mats achieved an impressive Cr(VI) reduction rate of up to 90.1 % under acidic conditions within 20 minutes and were recyclable for up to five cycles without loss of efficiency. Furthermore, Density Functional Theory (DFT) calculations, focusing on the Density of States (DOS), were performed to elucidate the underlying mechanisms contributing to the observed improvements in piezoelectric and piezocatalytic performance.

Morphology Regulation and Oxygen Vacancy Construction Synergistically Boosting the Piezocatalytic Degradation and Pure Water Splitting of SrTiO3.

In recent years, the development of high-efficiency piezoelectric materials is an effective means to make full use of the mechanical energy widely existing in the environment. However, there are few reports on multi-strategies synergistically improving piezocatalytic activity, and the mechanism of synergistic enhancement of piezocatalytic activity also receives less attention. Herein, the SrTiO3 nanorods decorated with tunable surface oxygen vacancy concentrations are prepared. Oxygen vacancy-optimized SrTiO3 nanorods exhibit efficient and undifferentiated piezocatalytic degradation activities for both anionic and cationic dyes under ultrasonic vibration. More importantly, it can split water into H2 and H2O2 with high production rates of 540 and 332 µmol g-1 h-1 without adding any sacrificial agents and cocatalysts, respectively. Mechanism analyses demonstrate that the 1D structure is beneficial to mechanical energy harvesting, and the surface oxygen vacancy induces larger surface asymmetry and piezoelectric response, synergically enhancing the piezocatalytic activity of SrTiO3 nanorods. In addition, metal deposition experiments under different conditions show that SrTiO3 nanorods possess abundant reactive catalytic sites in the piezocatalytic reaction process. This work provides a further understanding of piezocatalysis in piezoelectric nanomaterials and is important for the development of efficient piezoelectric catalysts.

High-yield preparation of 1T-MoS2 with excellent piezo-catalytic activity via W6+ doping for antibiotics degradation and Cr(VI) reduction: Mechanistic insights from characterizations to DFT calculations

Molybdenum disulfide (MoS2) is a promising piezoelectric material. Herein, a simple method is reported for the high-yield production of metallic (1 T) phase MoS2 which exhibits excellent piezo-catalytic activity by in-situ doping of trace amounts of W6+. At 1 wt% W6+ doping, the 1 T phase of the obtained MoS2 reaches a concentration as high as 85.56 % and the piezoelectric coefficient and piezoelectric response current increase by 1.67 and 1.18 times, respectively, as compared to pristine MoS2. Consequently, W1.0-MoS2 can remove more than 99.8 % of tetracycline and 97.3 % of Cr(VI) in 10 min. Experimental characterization and theoretical calculations indicate that the enhanced piezoelectric catalytic activity is attributed to the strong synergistic effect between 1T-MoS2 and W6+ doping, which facilitates the rapid generation of hydroxyl radicals and superoxide radicals. This new strategy of doping 1 T/2H-MoS2 with W6+ can significantly enhance the piezoelectric catalytic performance, providing important insights for the removal of pollutants.

Enhanced piezocatalytic RhB degradation with ZnSnO3 Nanocube-modified Bi4Ti3O12 composite catalyst by harnessing ultrasonic energy

With the increasing demand for effective methods to address environmental pollution, piezocatalysis has emerged as a promising approach for pollutant degradation under mechanical energy. However, the development of highly efficient piezocatalytic materials remains a challenge. This study aimed to increase the piezocatalytic activity of bismuth titanate (Bi4Ti3O12) by modifying it with zinc stannate (ZnSnO3) nanocubes. The composite catalysts were synthesized using a straightforward deposition and calcination process. The calcination process ensured the tight adhesion of ZnSnO3 nanocubes to the Bi4Ti3O12 surface, while facilitating strong interactions between ZnSnO3 and Bi4Ti3O12, which enhanced electron transfer and heterojunction structure formation. Band structure analysis indicated that Bi4Ti3O12 has higher conduction band and valence band potentials than ZnSnO3, forming a type-II heterojunction. Bi4Ti3O12 possesses a higher Fermi level than ZnSnO3, resulting in interfacial electron drift and formation of a built-in electric field, which further promotes the directional transfer and separation efficiency of charge carriers within the composite catalyst. This hypothesis was confirmed by surface photovoltage spectroscopy, piezoelectric current response, and electrochemical analysis. Consequently, the ZnSnO3/Bi4Ti3O12 composite exhibited significantly improved piezocatalytic performance in RhB degradation, achieving a degradation efficiency of 80 % within 90 min under ultrasonic vibration. The degradation rate of the optimal sample was 8.2 times that of Bi4Ti3O12 and 6.3 times that of ZnSnO3. Additionally, experiments to detect reactive species were conducted to elucidate the mechanism behind the piezocatalytic RhB degradation. Holes and hydroxyl radicals were the main reactive species. This study may offer new insights into the design of efficient piezocatalytic materials.

Dual boosting of the built-in polarization field in the BiFeO3/ZnS heterostructure for water purification: Effects of Z-scheme heterostructure and corona poling

In this study, we have designed a novel 1D-0D lead-free Z-scheme heterostructure of BiFeO3–ZnS (BFO/ZnS) using an isoelectric point-assistant annealing method for piezocatalytic reactions. The open circuit voltage measurements exhibited a greater internal electric field for BFO/ZnS (90/10) than for individual components, causing its excellent piezocatalytic performance for MTZ antibiotics, organic dyes oxidation, and Cr(VI) reduction. BFO/ZnS (90/10) was treated by corona poling to boost its polarization, resulting in the highest remanent polarization and dielectric constant. Piezocatalytic experiments demonstrated that BFO/ZnS (90/10; poled) can degrade 99% of RhB by 9 min ultrasonic vibration with kapp = 0.44 min−1, which is 2.5, 5.5, and 16.3 times greater than those of BFO/ZnS (90/10), BFO, and ZnS, respectively. Also, the efficiency of piezodegradation for MTZ, Cr(VI), MO, and MB over BFO/ZnS (90/10; poled) was found to be 74.5% (90 min), 84.6% (60 min), 95.3% (40 min), and 97.2% (30 min), respectively. This outstanding piezocatalytic performance of BFO/ZnS (90/10; poled) is ascribed to the enhanced built-in polarization field due to the Z-scheme heterostructure and corona poling treatment. As supported by PL and EIS analysis, the stronger built-in electric field can effectively separate and transmit the charge carriers, causing excellent piezocatalytic activity.

Mechanical-vibration-driven piezocatalytic degradation of organic pollutants over microcrystalline SnSe with selenium vacancies

Two-dimensional piezoelectric materials are attractive candidates to trigger piezoelectric catalytic reactions for organics degradation. Microcrystalline structures can endow them with enhanced piezocatalytic activity due totheir large surface area and abundant defect structures. In this work, microcrystalline SnSe with selenium vacancies (mc-SeVs SnSe) was synthesized and employed for piezocatalytic degradation of aqueous organics for the first time. Various instrumental testing results demonstrated that this unique microcrystalline SnSe has strong piezoelectric responses, abundant selenium vacancy defects and large active edges. Compared with crystalline SnSe, mc-SeVs SnSe showed superior piezocatalytic activity for the degradation of various organics in water. More importantly, mc-SeVs SnSe could induce the piezoelectric effect through mild mechanical energy to facilitate the efficient degradation of organic pollutants. The degradation efficiency of Crystal violet, p-nitrophenol, Malachite green, Congo red and Rhodamine B approached 100 % within 60 min reaction time. Superoxide and hydroxyl radicals were detected as the main reactive oxygen species generated in the piezocatalytic process. The degradation pathways of Rhodamine B were proposed based on high performance liquid chromatography-quadrupole-time of flight mass spectrum. The impact of strain on the alterations of dipole moment and electronic structure was investigated using density functional theory. The change in electron band structure induced by the polarized electric field was the underlying reason for the generation of hydroxyl radicals. This work will enrich the piezoelectric materials for organics degradation and provide fresh light on the mechanism of mechanically driven piezoelectric catalytic reactions.

Bismuth titanate microplates with tunable oxygen vacancies for piezocatalytic hydrogen peroxide production

Piezocatalysis offers an encouraging alternative for the sustainable, on-demand, and decentralized production of hydrogen peroxide (H2O2), underscoring the importance of enhancing piezocatalytic efficiency. Enhancing piezocatalysts through defect engineering has shown considerable potential in boosting H2O2 production efficiency. However, the impact of oxygen vacancies on piezocatalytic activity remains unclear. Herein, we used a chemical probe method to quantify negative charges (q−) and superoxide radicals (O2−) to explore the relation between the oxygen vacancy concentration and piezocatalytic performance of bismuth titanate (Bi4Ti3O12) based catalysts. Results indicate that piezocatalytic H2O2 production in pure water demonstrates a volcanic trend with increasing oxygen vacancy concentration. This trend is attributed to the dual role of oxygen vacancies, which reduce the piezoelectric property of the piezocatalyst while simultaneously increasing the concentration of O2−, which is crucial for H2O2 formation through the O2 reduction pathway. This study provides insights into the interplay between oxygen vacancies, piezoelectric properties, and piezocatalytic activity, offering valuable guidance for the design of piezocatalysts for sustainable H2O2 production.

Piezocatalytic effect induced by Schottky junction at interface of 0.5Ba(Zr0.2Ti0.8)O3 – 0.5(Ba0.7Sr0.3)TiO3

In water remediation applications ferroelectric materials have been shown wide applicability in catalysis due to their spontaneous polarization. 0.5Ba(Zr0.2Ti0.8)O3 – 0.5(Ba0.7Sr0.3)TiO3 (BST-BZT) pellets were examined for piezocatalysis activity by electrode effect. These samples were prepared using traditional solid-state reaction and sintering process. The samples were coated with silver paste using manual brushing resulting in Schottky junction having enhanced surface polarization and dye degradation capability. X-ray diffraction, Field emission scanning electron microscopy (FE SEM), and Raman spectroscopy were performed to confirm the phase, morphology and vibrational modes of prepared samples, respectively. Further, Diffuse reflectance spectra (DRS) and X-Ray Photoelectron spectroscopy (XPS) was done to check absorbance and chemical composition. Piezocatalysis activity on electrode sample was observed under 150W and 40kHz ultrasonication. Well dried samples showed enhanced dye degradation of 68%. It could be due to additional charges developed at the interface which act as Schottky junction along with triboelectric phenomenon. This highlights the significant impact of Schottky junction in electrode effect by enhancing the piezocatalytic activity.

Degradation of dye through mechano-catalysis using BaBi4Ti4O15 catalyst

Ferroelectric BaBi4Ti4O15 was prepared using solid-state calcination at 950 °C for four hours. X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy were utilized to understand its microstructure and other structural aspects. Particle size was around < 1.5 µm. This oxide is able to demonstrate piezocatalysis and tribocatalysis as reflected in its dye degradation performance. This oxide showed piezocatalytic activity around 40% in 2 h and tribocatalytic activity around 90% in 12 h. The rate constant for the piezocatalytic reaction is 0.003 min−1 and for tribocatalytic reaction is 0.169 h−1. The rotation speed also affected the tribocatalytic activity of the oxide. Oxide showed 25%, 90%, and 94% tribocatalytic activity at 300, 500, and 700 rpm respectively. This material has demonstrated notable performance of catalysis under different types of mechanical energy sources and under different mechanisms.

BaTiO3 nanocrystals with tunable exposed {001} polar facets: A high-performance piezocatalyst and piezoelectric regenerative medicine

Piezocatalysis triggered by ultrasonic vibration has emerged as an effective strategy to address the widespread environmental challenges and human health concerns. Nevertheless, the pursuit of high-performance piezoelectrics that can simultaneously realize catalysis and biotherapy still poses a significant challenge. Herein, we report a notable enhancement in piezocatalytic performance of BaTiO3 nanoplates featuring highly exposed {001} facets. By controlling the exposure of polar facets, BaTiO3 with highly {001} facets (I{001}/I{110} = 4.17) exhibits an impressive 1500 % improvement in degradation efficiency compared to BaTiO3 with less-exposed {001} facets (I{001}/I{110} = 0.76). Through in vitro ultrasonic stimulation, BaTiO3 also demonstrates a remarkable ability to regenerate neurons, facilitating the rapid differentiation of neural progenitor cells into mature neurons. The mechanism of how polar facets enhance the piezocatalytic activity is systematically investigated by finite element method (FEM) simulation and density functional theory (DFT) calculations, revealing that the enhancement stems from the abundant active sites and strong charge transfer ability. This study thus offers a comprehensive understanding of the relationship between polar facets and piezocatalytic performance, also providing inspiration for the development of high-performance piezoelectric medicine for nerve repair.

Boosting piezocatalytic efficiency: Thin carbon layer-modified ZnO for superior rhodamine B degradation

This study aims to enhance the piezocatalytic activity of ZnO by modifying it with a thin carbon layer (TCL). The composite catalysts were synthesized using a simple hydrothermal method. The tightly adhered TCL served as an effective electron transfer medium, enabling the rapid migration of piezoinduced charge carriers from the ZnO to the catalyst surface, thereby facilitating the catalytic degradation of Rhodamine B (RhB). The optimized TCL/ZnO sample exhibits an RhB degradation rate 13.4 times higher than that of pure ZnO. This work demonstrates that TCL/ZnO has significant potential in piezocatalytic water purification and offers new insights into the design of efficient piezocatalytic materials.

SnS2: A piezocatalytic material for efficient degradation of ciprofloxacin

Tin disulfide (SnS2), as a two-dimensional transition metal sulfide with similar electronic or structural properties, has been calculated to have the possibility of piezoelectricity. SnS2 was prepared by different methods, the structure of materials were characterized by XRD and FT-IR. Then the morphology and surface elements of materials were characterized by SEM and XPS. Through the detection of PFM and electrochemical transient currents, the results show that the SnS2 samples prepared by coprecipitation method have piezoelectric characteristics and current can be generated by applying mechanical stirring force. Comparing the materials that prepared by coprecipitation method, hydrothermal method and commercially purchased SnS2, it was found that the degradation rate of ciprofloxacin by the material prepared by the coprecipitation method could reach 93 % after 1 h. Through characterization, it is speculated that the piezocatalytic activity of the coprecipitation material is due to sodium ion doping. It is found that the preparation method and the introduction of heteroatoms have a great influence on the piezocatalytic activity. It provides a way for subsequent researchers to improve the performance of materials from material design.

Remarkably Boosting Piezocatalytic Performance of Sr0.5Ba0.5Nb2O6 Piezoceramics via Size Optimization and Oxygen Vacancy Engineering

AbstractPiezocatalysis is capable of harnessing mechanical energy for environmental remediation, which is regarded as a green and promising technology to be exploited. Piezoceramics are struggling to be used as highly efficient piezocatalysts due to their grain size reaching tens of micrometers usually. Herein, a feasible and straightforward method is proposed to turn piezoceramic powders into highly efficient piezocatalysts by integrating size optimization and oxygen vacancy modulation. This strategy is validated by treating lead‐free Sr0.5Ba0.5Nb2O6 (SBN) piezoceramic powders with high‐energy ball‐milling (hBM). The rate constant k value of 46.95 × 10−3 min−1 for rhodamine B (RhB) piezocatalytic degradation of SBN‐hBM‐12h is almost 18 times higher than that of pristine SBN. Besides, the SBN‐hBM‐12 h catalyst performed superior antibacterial properties against Escherichia coli. The enhanced piezocatalytic efficiency is attributed to the introduced abundant oxygen vacancies absorbing and activating O2 into reactive oxygen species. Well‐modulated oxygen vacancy concentration can effectively accelerate the generation and separation of free carriers. However, the excess oxygen vacancies in SBN render the weakened piezoresponse thus suppressing the piezocatalytic activity. This study elucidates the critical role of oxygen vacancies in piezocatalysis and provides insights into the development of efficient piezocatalysts.

Doping-Induced piezoelectricity in Ba2Nb2-xFexO6-δ double perovskite oxides for efficient hydrogen peroxide production via piezocatalysis in pure water

Piezocatalysis has emerged as a sustainable alternative for hydrogen peroxide production. However, the current development of efficient piezocatalysts is predominantly focusing on those conventional piezoelectric ceramic oxides with high permittivity and limited catalytic activities. Therefore, innovative approaches to develop novel piezocatalysts in particular from these outstanding paraelectric semiconductors are highly required. In this work, by employing a feasible doping strategy, robust piezoelectric property is created on the Ba2Nb2-xFexO6-δ double perovskite oxides, typically characterized by a stable paraelectric cubic structure. Optimum Fe doping not only intensifies the double perovskite phase but also inspires a phase transition from a centrosymmetric cubic to a piezoelectric tetragonal phase, thereby achieving desirable piezoelectricity and enabling a series of favorable physical properties including redox activity, active sites of anion defects, reduced bandgap, and increased free charge density. All these are important factors to enhance piezocatalytic activity. As a result, Ba2NbFeO6-δ achieved by the optimum Fe doping demonstrated exceptional piezocatalytic H2O2 yield of 512 and 690 µmol g-1 h−1 under atmosphere and oxygen-purging conditions, respectively, without the presence of any sacrificial agents. Mechanistic investigations reveal that both water oxidation and oxygen reduction involve in the H2O2 production, wherein piezopotential plays a critical role not only in facilitating the charge carrier separation and transportation but also in modulating the band structure to enhance the catalyst redox capacity. This study offers a feasible and universal strategy for the design of novel piezocatalysts, expanding the windows for catalyst selection for piezocatalysis.

Enhancing production of hydrogen and simultaneous degradation of ciprofloxacin over Sn doped SrTiO3 piezocatalyst

The combination of hydrogen production from water and degradation of organic pollutants into a single reaction system is an attractive and promising solution for renewable energy generation and wastewater treatment. Herein, the piezocatalytic production of hydrogen coupled with simultaneous piezocatalytic degradation of organic antibiotic (ciprofloxacin) was successfully achieved using Sn doped SrTiO3 as the highly efficient and robust piezocatalyst through harvesting vibration energy. Results showed that 5 mol% Sn doped SrTiO3 (SrSn0.05Ti0.95O3) showed the highest piezocatalytic production rate of hydrogen (101.46 μmol g−1h−1) in water. And SrSn0.05Ti0.95O3 also exhibited remarkable piezocatalytic activity in solution containing ciprofloxacin with 151.03 μmol g−1h−1 of H2 evolution rate and 77.5 % of ciprofloxacin degradation efficiency within 60 min. In this process, the doping of Sn largely enlarged the distorted structure and conductivity of SrTiO3 to improve the piezocatalytic activity, and the organic ciprofloxacin mainly acted as the electron donors to synergistically improve the reduction process for H2 evolution. This work establishes the relationships between the piezoelectric property and the piezocatalyst structure, and provides an approach of advanced piezocatalytic technology for wastewater treatment and renewable energy generation.

CuS@MoS2 p[sbnd]n heterojunction photocatalyst integrating photothermal and piezoelectric enhancement effects for tetracycline degradation

Photocatalysis is an environmentally friendly and low-cost technology for the degradation of pollutants. In addition to the construction of heterojunction which may decrease the recombination of charge carriers and extend the photo-response range, the utilization of piezoelectricity and photothermal conversion also provides the promising routes to improve the photocatalytic performance. Herein, a CuS@MoS2 heterostructure was developed to simultaneously meet the needs of these enhancement mechanisms. The formation of pn heterojunction was confirmed and the associated energy band diagram was constructed with band gaps of CuS and MoS2 as 1.56 and 1.80 eV, respectively. For the degradation of tetracycline, it was demonstrated that the inherent piezoelectric property of MoS2 surface enhanced the piezocatalytic activity by inducing an electric field to aid charge separation. The heat generated by illumination raised the photocatalytic reaction rate by supplying extra energy to carriers. The CuS@MoS2 heterostructure exhibited significantly better catalytic performance than the individual CuS or MoS2 due to the formation of pn heterojunction. Furthermore, the combination of piezoelectricity and photothermal conversion also led to a significant synergistic effect, achieving a degradation efficiency of over 95% within 30 min. As compared to the conditions under ultrasonic vibration, visible light irradiation and visiblenearinfrared light irradiation alone, the combination of visiblenearinfrared irradiation and ultrasonic vibration could lead to 96, 205 and 81% enhancement. This work provides valuable insights into the design of novel heterojunction photocatalysts integrating the piezoelectric and photothermal enhancement effects.

Lattice strain engineered reactive oxygen species generation of NaNbO3 ferroelectric

The generation of reactive oxygen species (ROS) using ambient mechanical energy with piezoelectric materials is emerging as a promising method for producing renewable green oxidants. However, the low piezoelectricity and limited electron-hole pair separation efficiency significantly hinder its productivity. Here, non-stoichiometric Na1-xNbO3-δ perovskites with lattice strain and ferroelectric enhancement were successfully designed to boost the piezo-catalytic activity. Significantly, hydrogen peroxide (H2O2), superoxide radicals (•O2-), and hydroxyl radicals (•OH) were powerfully generated by the Na0.95NbO2.975 piezo-catalyst through redox reaction with rates of 362.4, 69.3, and 65.0 µmol∙g−1∙h−1, respectively, and the yield of H2O2 was approximately three times higher than that of the stoichiometric NaNbO3. The elevated piezoelectricity and polarization electric field effects induced by lattice strain could promote the generation of electron-hole pairs and drive them to separate facilely. The distribution of sodium vacancies and oxygen vacancies in the crystal lattice enhanced the diffusion of carriers for fast migration to the opposite surface of the catalyst. Furthermore, the presence of Na defects enhanced the adsorption of O2 on the Na1-xNbO3-δ surface and contributed to the catalytic generation of H2O2. This work provides a novel and effective methodology for the design of high-performance piezo-catalysts with lattice-strained engineering and broadens the strategy for improved H2O2 evolution efficiency.

Poling‐induced enhancement of piezocatalytic performance of 0.96K0.5Na0.5NbO3‐0.04Bi0.5Na0.5ZrO3 ceramic blocks

AbstractCompared with powder particles, ceramic block piezocatalyst possesses the advantages of high cycle stability, decreasing secondary pollution, and easy recovery. Herein, with a simple strategy of the poling procedure, the piezocatalytic activity of 0.96K0.5Na0.5NbO3‐0.04Bi0.5Na0.5ZrO3 (abbreviated as 0.96KNN‐0.04BNZ) ceramic blocks can be considerably improved. A reaction rate constant k value of 14.70×10−3 min−1 in the poled sample can be obtained to degrade Rhodamine B, which is 3.44 times that of the unpoled one. Meanwhile, the poled sample also has good degradation effects against methylene blue and amino black 10B. The improvement of piezocatalytic activities originates from the reduction of crystal symmetry and the enhancement of electron‐hole pair separation, which accelerates the generation of charge carriers. This research displays a unique lead‐free bulk piezocatalyst and a convenient method for enhancing its piezocatalytic activity.