Piezocatalytic Activity Research Articles

Boosting tetracycline degradation of BaTiO3-based piezo-catalysts via modulating phase boundary and band structure

Piezoelectric catalysis, which converts mechanical energy into chemical activity, has important applications in environmental remediation. However, the piezo-catalytic activity of various piezoelectric materials is limited by the weak piezoelectricity as well as the mismatched band-gap, leading to inefficient electron-hole pair generation and difficult carrier migration. Here, a simple strategy combining phase boundary and energy band structure modulation was innovatively proposed to enhance the piezo-catalytic activity of BaTiO3 ferroelectric by Ce ions selecting different doping sites. Thanks to the coexistence of tetragonal (P4mm) and orthorhombic (Amm2) phases effectively flattened the Gibbs free-energy and thus enhanced the piezoelectric activity, as well as suitable energy bandwidth facilitating the carrier migration were realized in the B-sites doped Ba(Ti0.95Ce0.05)O3. The degradation rate constant k of tetracycline (TC) was high to 30.56 × 10-3 min−1, which was 2.03 times higher than that of pure BaTiO3 and superior to most representative lead-free perovskite piezoelectric materials. Theoretical calculations validated that the charge density and high O2 and OH– adsorption energy on the Ba(Ti0.95Ce0.05)O3 surface promoted more efficient •O2– and •OH radicals conversion and bettered response to piezo-catalytic reaction. This work is important to design high-performance piezo-catalysts by synergistic regulation of phase boundary and energy band structure in perovskite materials for long-term antibiotic tetracycline removal.

Efficient piezocatalytic properties of Na0.5Bi0.5TiO3 nanoparticles for dye degradation and hydrogen peroxide production

Piezocatalysis has emerged as a promising environmental remediation technique, and the exploration of environmentally friendly and high-performance piezocatalysts is crucial for their practical applications. In this work, the bismuth sodium titanate (Na[Formula: see text]Bi[Formula: see text]TiO3 (NBT)) exhibited efficient piezocatalytic activity toward typical organic pollutants degradation, including acid orange 7, methylene blue, rhodamine B and methyl orange. Notably, rhodamine B was degraded by 98.1% within 30[Formula: see text]min with a reaction rate constant of 0.130[Formula: see text]min[Formula: see text]. Furthermore, the NBT achieved a hydrogen peroxide production efficiency of 538[Formula: see text][Formula: see text]mol/g⋅h without the sacrificial agent, indicating that the NBT is a superior piezocatalyst for dye degradation and hydrogen peroxide generation. This work demonstrated that by using mechanical energy, the NBT can be used for degrading organic pollutants in wastewater and hydrogen peroxide generation.

Synergistic piezocatalytic activity of hybrid BZT/Graphene/PVDF composites

In this study, piezocatalyst composites were synthesized using hybrid films of Ba(Zr,Ti)O3/Polyvinylidene fluoride (BZT/PVDF) with graphene nanoplatelets (GNP) for the Rhodamine B (RhB) discoloration. X-ray diffraction and Raman spectroscopy analyses confirmed composite formation without altering short/long-range structures, stabilizing the β phase of PVDF. Scanning electron microscopy revealed crucial morphological changes influencing the piezocatalytic response of the films. RhB discoloration tests underscored the efficacy of BZT/GNP/PVDF composites due to enhanced system polarization provided by GNP. This work provides insights into the delicate balance of components for flexible, heavy metal-free piezocatalyst composites, advancing their design and applications.

PVDF-Based Piezo-Catalytic Membranes-A Net-Zero Emission Approach towards Textile Wastewater Purification.

Among the various water purification techniques, advancements in membrane technology, with better fabrication and analysis, are receiving the most research attention. The piezo-catalytic degradation of water pollutants is an emerging area of research in water purification technology. This review article focuses on piezoelectric polyvinylidene difluoride (PVDF) polymer-based membranes and their nanocomposites for textile wastewater remediation. At the beginning of this article, the classification of piezoelectric materials is discussed. Among the various membrane-forming polymers, PVDF is a piezoelectric polymer discussed in detail due to its exceptional piezoelectric properties. Polyvinylidene difluoride can show excellent piezoelectric properties in the beta phase. Therefore, various methods of β-phase enhancement within the PVDF polymer and various factors that have a critical impact on its piezo-catalytic activity are briefly explained. This review article also highlights the major aspects of piezoelectric membranes in the context of dye degradation and a net-zero approach. The β-phase of the PVDF piezoelectric material generates an electron-hole pair through external vibrations. The possibility of piezo-catalytic dye degradation via mechanical vibrations and the subsequent capture of the resulting CO2 and H2 gases open up the possibility of achieving the net-zero goal.

Facilitating flexoelectric effect in BaTiO3 ceramic for pollutant removal application via piezocatalysis process

Flexoelectricity is an inherent property of some insulators, causing them to undergo polarization in response to non-uniform or inhomogeneous deformation. Further, with advanced scientific knowledge, its applicability is increasing day by day. The present study reports one of the possible applications of the flexoelectric effect in the catalysis field. For this, the sintered BaTiO3 ceramic pellet was subjected to 150° C temperature for 2 h which in response created oxygen vacancies on the BaTiO3 ceramic pellet. Furthermore, due to heat treatment, there is a generation of strained surface whereby developing flexoelectric effect on the surface generating higher piezoelectric potential on the surface. Piezoelectric force microscopy (PFM) was employed to analyze the amplification of piezopotential resulting from a strained surface. The enhanced piezopotential contributed towards more piezocatalytic activity whereby efficiently degraded Methylene Blue (MB) dye. As a result, the flexoelectric effect in the BaTiO3 ceramic pellet showed 1.47 times more MB dye degradation compared to the sintered BaTiO3 ceramic pellet.

Regulation of phase composition and oxygen vacancy in hydrothermally synthesized NaNbO3 nanowire and its enhanced piezocatalytic activity for antibiotic elimination

Piezocatalysis based on piezoelectricity has shown potential for environmental remediation and production of clean energy, which, however, cannot meet the standard of practical application due to its insufficiency. Herein, we successfully regulated phase composition (monoclinic, orthogonal and amorphous) in NaNbO3 nanowire through controlling the annealing temperature and time, where the decreased structural symmetry at the two-phase interface improved the piezoelectricity and meanwhile the increased oxygen vacancies in amorphous structure acted as active sites to promote charge separation and oxygen adsorption. As a result, the optimized NaNbO3 sample annealed under 350 °C for 2 h presented much higher piezocatalytic activity for antibiotic degradation than the pristine NaNbO3. In detail, the effects of pH, antibiotic concentration, antibiotic type and reusability on the piezocatalytic performance were systematically studied. The enhanced piezocatalytic activity of the annealed NaNbO3 was revealed through testing piezoelectric coefficient, surface potential, piezoelectric current response and generation rate of active oxygen species, and therefore a possible piezocatalytic mechanism was proposed. Based on the determined intermediate products in the antibiotic degradation process, the reasonable degradation pathway was suggested.

High-entropy doping and defect co-engineering to synergistically boost piezo-catalytic activity of BaTiO3-based materials

Recently, piezo-catalytic technology with low cost, simplicity and feasibility are drawing more attention in the field of water pollution remediation; nevertheless, the catalytic activity of diverse piezoelectric materials is limited by the rapid recombination of electron-hole pairs and low carrier mobility. Herein, a collaborative strategy of entropy and defect engineerings is proposed to enhance the piezo-catalytic activity of BaTiO3-based materials ((1-x)BaTiO3-xSm(Ca0.2Zn0.2Zr0.2Sn0.2Hf0.2)O3). As x increases, the configuration entropy of the materials is greatly increased from 0 R to 1.3227 R, suggesting that the ceramics with x = 0.05, 0.10, 0.15 and 0.20 possess significantly increased disordering and the ferroelectric long-range order is broken, rendering the materials rich in catalytically active sites and thus enhancing the catalytic performance. In addition, the doping of multiple ions with different ionic radii and valence states leads to abundant oxygen vacancies inside the material, thereby enabling easier separation and migration of electron-hole pairs and resulting in enhanced catalytic activity. Accordingly, the high-configuration-entropy 0.90BaTiO3-0.10Sm(Ca0.2Zn0.2Zr0.2Sn0.2Hf0.2)O3 material with abundant oxygen vacancies exhibits outstanding piezo-catalytic activity, giving the reaction rate constant k of 38.7 × 10−3 min−1 for rhodamine B (RhB). Simultaneously, the 0.90BaTiO3-0.10Sm(Ca0.2Zn0.2Zr0.2Sn0.2Hf0.2)O3 material also show favorable catalytic activity for methylene blue (MB) and methyl orange (MO) with reaction rate constants k of 31.8 × 10−3 min−1 and 19.4 × 10−3 min−1, respectively. This work proposes a novel strategy for enhancing the piezo-catalytic activities of BaTiO3-based piezoelectric materials by the co-engineering of high-entropy doping and defect.

A comprehensive analysis of the structural, microstructural, optical, and piezocatalytic activity of Ba0.92Ca0.08Zr0.09Ti0.91O3 and Ba0.98Ca0.02Zr0.07Ti0.93O3 lead-free ceramics

Through this study, we aim to comprehensively explore the piezocatalytic efficiency of Ca2+ and Zr4+ co-substituted BaTiO3 (BT) based ceramics Ba0.92Ca0.08Zr0.09Ti0.91O3 (BCZT-92) and Ba0.98Ca0.02Zr0.07Ti0.93O3 (BCZT-98), synthesized through the solid-state reaction method. Furthermore, the study delves into the interplay between the structural, microstructural, optical, and piezocatalytic properties of these ceramics. The coexistence of tetragonal (T, P4mm) and orthorhombic (O, Amm2) phases in both ceramics was verified through the Rietveld refinement of the X-ray diffraction patterns along with the analysis of the Raman spectra. The optical properties, investigated using the Tauc’s model, revealed an indirect bandgap in both compounds. Other optical parameters such as the Urbach energy (Eu), extinction coefficient (k), and refractive index (n) were also calculated from the absorbance data. The dispersion parameters (E0 and Ed) were estimated using the Wemple and Di-Domenico model. In contrast to BCZT-92 compound, BCZT-98 demonstrated improved piezocatalytic degradation efficiency presumably due to its lower bandgap energy, more oxygen defects, and increased surface charges. It is shown that kinetic factors such as initial dye concentration, catalytic dosage, and stirring speed influence the degradation performance of the BCZT-98 compound. The degradation efficiency as high as 82.7% with a rate constant of 0.03163 min−1 was achieved on Rhodamine B dye. The implications of these findings are significant in advancing the development of lead-free piezocatalysts with meticulously tailored dopants concentrations, fostering real-world applications in environmental remediation.

Oxygen vacancies mediated ultrathin Bi4O5Br2 nanosheets for efficient piezocatalytic peroxide hydrogen generation in pure water

The industrial anthraquinone method for H2O2 production has the serious flaws, such as high pollution and energy consumption. Piezocatalytic H2O2 evolution has been proven as a promising strategy, but its progress is hindered by unsatisfied energy conversion efficiency. Hence, we report the efficient piezocatalytic H2O2 generation in pure water over oxygen vacancies mediated ultrathin Bi4O5Br2 nanosheets (~5 nm). Oxygen vacancies and thin nanostructure not only enhance the piezoelectric properties of Bi4O5Br2, but also advance the separation and transfer of piezoinduced charges. Moreover, density functional theory (DFT) calculations also prove that the introduction of oxygen vacancies enhances the O2 adsorption and activation ability with largely decreased Gibbs free energy of the reaction pathway. Profiting from these advantages, ultrathin Bi4O5Br2 nanosheets optimized by oxygen vacancies exhibit a prominent H2O2 evolution rate of 620 µmol g−1 h−1 in pure water and 2700 µmol g−1 h−1 in sacrificial system, dominated by a two-step single electron reaction, which exceeds most of reported piezocatalysts. This work demonstrates that oxygen vacancies and ultrathin structure can synergistically enhance the piezocatalytic performance, which presents perspectives into exploring the strategies of defects and nanostructure fabrication for promoting piezocatalytic activity.

Ce-regulating defect and morphology engineering for efficiently enhancing the piezocatalytic performances of BiOBr.

Cerium-doped bismuth oxybromide (1%, 5% and 10% Ce-BiOBr) piezocatalysts were synthesized. The piezocatalytic activity was efficiently regulated by defect and morphology engineering. Among them, the 5% Ce-BiOBr exhibits the highest piezocatalytic hydrogen production property with an evolution rate of 1147.6 μmol g-1 h-1, nearly twice that of the original BiOBr. Additionally, the MO dye degradation efficiency of 5% Ce-BiOBr reaches 91.9% within 60 min, with a higher reaction kinetic constant (0.0376 min-1) that was 6.1 times larger than that of pure BiOBr. These outstanding performances of 5% Ce-BiOBr surpass those of most other piezocatalytic material systems.

Borophene: a piezocatalyst for water remediation.

Borophene is an emerging two-dimensional material exhibiting exceptional piezocatalytic activity under the influence of ultrasonic vibrations, as exemplified herein by the decomposition of highly stable organic dyes in water. After 6 minutes of exposure, borophene sheets converted up to 92 percent of a mixture of dye molecules at room temperature.

Resonance of KNbO3 nanofibers is effectively stimulated by ultrasound with low frequency and low power to enhance piezocatalytic activity

Resonance-activated KNbO3 nanofibers have significant strain-induced piezoelectric potential, facilitating the conversion of mechanical to chemical energy. The presence of resonance-enhanced mechanism can reduce the requirement for ultrasonic power input.

Sonochemically synthesized black phosphorus nanoparticles: a promising candidate for piezocatalytic antibacterial activity with enhanced dielectric properties.

The drawbacks inherent to traditional antibacterial therapies, coupled with the escalating prevalence of multi-drug resistant (MDR) microorganisms, have prompted the imperative need for novel antibacterial strategies. Accordingly, the emerging field of piezocatalysis in semiconductors harnesses mechanical stress to drive chemical reactions by utilizing piezo-generated free charge carriers, presenting a promising technology. To the best of our knowledge, this study is the first to provide a comprehensive overview of the eradication of pathogenic S. aureus bacteria using few-layer black phosphorus (SCBP) piezo catalyst under mechanical stimuli, along with the exploration of temperature dependent dielectric properties. The synthesis of the piezo catalysts involved a one-step cost-effective sonochemical method, and its structural, morphological, elemental, optical, and overall polarization properties were thoroughly characterized and compared with the traditional method-derived product (TABP). The synthesis-introduced defects, reduced crystalline diameters, modified bandgap (1.76 eV), nanoparticle aggregation, photoluminescence quenching, along with interfacial polarization, synergistically contribute to SCBP's exceptional dielectric response (4.596 × 107 @40 Hz), which in turn enhanced the piezocatalytic activity. When subjected to soft ultrasound stimulation at 15 kHz, the piezo catalyst SCBP demonstrated significant ROS-mediated antibacterial activity, resulting in a ∼94.7% mortality rate within 40 minutes. The impact of this study extends to cost-effective energy storage devices and advances in antibacterial therapy, opening new dimensions in both fields.

Ultrathin Ba0.75Sr0.25TiO3 nanosheets with highly exposed {001} polar facets for high-performance piezocatalytic application.

The development of piezoelectrics with high catalytic activity to address environmental pollution and energy shortage has long been pursued. In this work, for the first time, a "three-birds-with-one-stone" strategy is proposed to design high-activity piezocatalysts. Interestingly, we achieved ultrathin, highly exposed polar facets and ferroelectric-paraelectric phase transitions in Ba1-xSrxTiO3 nanosheets simultaneously. As expected, Ba0.75Sr0.25TiO3 shows superior piezocatalytic performance for organic pollutant degradation due to its excellent flexibility, highly exposed polar area, and short carrier migration distance. Then, the piezoelectric potential distribution and electron transport ability on the interface of Ba0.75Sr0.25TiO3 were investigated through finite element method (FEM) simulation and density-functional theory (DFT) calculations, which provided a deep insight into the enhanced mechanism. This work thus presents a novel strategy for designing high-performance piezocatalysts and provides new insights for the optimization of the piezocatalytic activity by combining multiple advantages.

Boosting piezocatalytic performance of perovskite BiFeO3 with controlled oxygen vacancies

Piezocatalysis, which is capable of directly converting mechanical energy into chemical energy, has been identified as a promising strategy for environmental wastewater remediation and clean energy production. Regrettably, the present piezocatalysis is still in the early stage and the piezocatalytic activity is still far from ideal. Thus, exploring and discovering more efficient catalyst design strategies remains a challenge. In this work, a novel and simple method was employed to synthesize a piezocatalytic BiFeO3 (BFO) using metal-organic frameworks (MOFs) as precursors, and the MOFs derived BFO (MOF-BFO) has excellent piezocatalytic activity. The maximum reaction rate constant (k) for rhodamine B (RhB) can reach 1.70 × 10−2 min−1, which is about 4.7 times that of the sample annealed at 700 °C (BFO-700, 0.36 × 10−2 min−1) and about 10.3 times that of the sample annealed at 450 °C (BFO-450, 0.17 × 10−2 min−1) using conventional one pot co-precipitation method. The MOF-BFO catalyst is also suitable for degradation of other typical dyes, including methylene blue (MB) and methyl orange (MO), dramatically increasing its utility against complex wastewater components. What's more, the analysis indicates that the concentration of oxygen vacancy (OV) may be the primary factor influencing the piezocatalytic performance. Thus, the effect of OV concentration on piezocatalytic activity is further studied, which acts like a double-edged sword, manifesting that creating moderate OV is crucial for regulating piezocatalytic performance. This study not only demonstrates the potential of MOF-BFO as a candidate material for piezocatalytic applications, but also offers insights for the development of efficient piezocatalysts in future.

Constructing of GQDs/ZnO S-scheme heterojunction as efficient piezocatalyst for environmental remediation and understanding the charge transfer mechanism

Highly efficient catalysts are challenging in the fields of environmental remediation. In this work, for the first time, we combined graphene quantum dots (GQDs) and piezocatalytic materials (ZnO) to construct a novel S-scheme GQDs/ZnO heterojunction via facile method. The obtained GQDs/ZnO heterojunction presented excellent piezocatalytic activity such as higher reaction kinetic rate constant (0.051 min−1) and degradation efficiency (96.1 % within 60 min) as well as superior stability toward methyl orange (MO) dye degradation, far exceeding those of pure ZnO and most reported other typical piezocatalysts. This superior piezocatalytic performance of GQDs/ZnO could be ascribed to S-scheme heterojunction facilitating charge carrier transfer and separation, and enhancing the redox ability as well as the formation atomic-level interfacial bridge of Zn–C–O bond at GQDs/ZnO interface. Furthermore, density functional theory (DFT) calculations demonstrated the charge transfer path of GQDs/ZnO S-scheme heterojunction and provided a novel understanding for S-scheme heterojunction mechanism in piezocatalytic field, which supports the experimental evidences of S-scheme heterojunction. This research provides an effective strategy to modulate charge transfer from the atomic level, highlighting an innovative insight for the practical application of highly efficient piezocatalysts in environmental remediation.

Lead‐Free (K, Na)NbO3 Piezocatalyst with Superior Piezocatalysis and Large‐Scale Production

AbstractAlthough piezocatalysis has achieved preliminary achievements in environmental remediation and biomedical applications, large‐scale fabrication of piezocatalysts with high degradation efficiency and low cost remains challenging. In this work, a new and easy strategy to solve this challenge is innovatively proposed, that is, ceramic‐powder‐driven boosted polarization intensity, and validated the strategy is by examining potassium sodium niobate ((K, Na)NbO3, KNN) ferroelectric. KNN‐3 piezocatalyst, obtained by grinding as‐sintered ceramics into powder, shows a degradation rate (k) as high as 148 × 10−3 min−1 for rhodamine B (RhB) dye and for 31 × 10−3 min−1 for methyl orange (MO) dye, ≈18 times and 66 times than those of previously reported KNN piezocatalysts. The superior piezocatalytic activity is attributed to enhanced polarization intensity, increased oxygen vacancies, and higher charge carrier concentrations. Besides, the KNN‐3 piezocatalyst shows excellent inhibitory effects on Staphylococcus aureus and Escherichia coli strains. Therefore, the proven ceramic preparation technology enables the new strategy to mass produce high‐performance KNN piezocatalysts that hold promise for applications in dye degradation and biomedicine.

Revealing the Mutually Enhanced Mechanism of Necroptosis and Immunotherapy Induced by Defect Engineering and Piezoelectric Effect.

Owing to low immunogenicity-induced immune escape and short-term circulating immune responses, the efficiency of immunotherapy is unsatisfactory. Therefore, triggering immunogenic cell death and establishing a long-term, mutually reinforced treatment modality are urgent challenges. In this study, ultrathin CaBi2 Nb2 O9 nanosheets with tunable oxygen vacancies (abbreviated as CBNO-OV1) are prepared for synergistic necroptosis and immunotherapy. The optimized vacancy concentration significantly improves the piezoelectric effect under ultrasound irradiation, thereby considerably improving the generation of reactive oxygen species (ROS). Density functional theory shows that oxygen vacancies can improve the efficiency of electron hole separation by suppressing their recombination, thus resulting in enhanced piezocatalytic activity. Moreover, the piezoelectric effect improves the permeability of tumor cell membranes, thus resulting in Ca2+ influx. Additionally, CBNO-OV1 also releases a portion of Ca2+ , which induces necroptosis assisted by explosive ROS. Ribonucleic acid transcription tests suggest the mechanisms associated with immune response activation and necroptosis. More importantly, necroptosis can trigger a significant immune response in vivo, thus activating macrophage M1 polarization through the NF-kappa B pathway and promoting T-cell differentiation.Tumor Necrosis Factor-α differentiated from macrophages conversely promotes necroptosis, thus realizing a mutually enhanced effect. This study demonstrates the feasibility of mutually reinforced necroptosis and immunotherapy for amplifying tumor efficacy.

A novel Ag2O/Bi2WO6 composite with enhanced piezocatalytic performance for ciprofloxacin removal

Bi2WO6, an important semiconductor material, has been widely used in the catalytic degradation of organic wastewater in recent years. However, Bi2WO6 owns the low band gap energy, the recombination of the produced e−-h+ pairs expected to be fast, which leads to undesirable degradation effects. In order to improve its piezocatalytic ability, this paper combined the semiconductor material Bi2WO6 with Ag2O to form Ag2O/Bi2WO6 piezoelectric catalysts, which was characterized and its removal effect on ciprofloxacin (CIP) was discussed. According to the analyses, the reaction rate constant for the piezocatalytic removal of CIP in the company of 5 % composite ratio of Ag2O/Bi2WO6 was about 1.40 and 4.87 times higher than it was when Bi2WO6 and piezocatalytic technology were used alone. By exploring the experimental principle, the increased piezocatalytic activity of Ag2O/Bi2WO6 was found to be due to the creation of Z-scheme heterojunction, which could efficiently separate the e−-h+ pairs. Reuse experiments were also carried out, and the results showed that it has good reusability and stability in piezocatalysis. In summary, Ag2O/Bi2WO6 has good piezocatalytic activity for the removal of CIP.

2D/2D KNbO3/MoS2 heterojunctions for piezocatalysis: Insights into interfacial electric-fields and reactive oxygen species

Developing and designing an excellent environmental cleanup piezocatalyst remains a considerable challenge for realizing a highly effective conversion of mechanical vibration energy into the chemical activity. Herein, the 2D/2D heterojunctions of ferro-/piezoelectric KNbO3/MoS2 nanosheets were rationally designed and constructed to satisfy this goal. Under ultrasonic vibration, the 2D/2D KNbO3/MoS2 heterojunction could simultaneously remove tetracycline hydrochloride (TC) and Rhodamine B (RhB). After 30 min of piezocatalysis, the reaction rate constants (k) were 0.085 min−1 and 0.092 min−1 for TC and RhB, which were near 17.0 and 6.1 times higher than that of pristine KNbO3, respectively. Additionally, the antibacterial properties of the 2D/2D heterojunction reached more than 99.77% against Escherichia coli and 60.03% against Staphylococcus aureus within 10 min ultrasound treatment, respectively. The strong piezocatalytic activity was attributed to: (1) the polarization-modulated interfacial electric-fields were realized through the desirable ferro-/piezoelectric 2D/2D nanostructures, (2) intimate and large interfaces were constructed between KNbO3 and MoS2 nanosheets, which created unique opportunities for facilitating free charges transfer, (3) KNbO3/MoS2 heterojunctions represented two reactive oxygen species of •O2- and •OH were greatly enhanced in contrast to bare KNbO3 and MoS2, supporting the observation of efficiently piezocatalytic activity. Overall, this research illustrates the effect of a wonderful and stable catalyst for environmental remediation and brings new inspirations for engineers to develop high-efficiency piezocatalysis for multifunctional environmental applications.