Open Access

High piezocatalytic performance driven by peak flow kinetic energy in polymer piezoelectric composite films

Jiangxi Key Laboratory of Green General Aviation Power, School of Power and Energy, Nanchang Hangkong University, Nanchang, Jiangxi 330063, P. R. China

Search for more papers by this author

Bing Xie

https://orcid.org/0000-0003-2402-064X

Jiangxi Key Laboratory of Green General Aviation Power, School of Power and Energy, Nanchang Hangkong University, Nanchang, Jiangxi 330063, P. R. China

E-mail Address: xieb@nchu.edu.cn

Search for more papers by this author

Zhiyong Liu

https://orcid.org/0000-0003-2044-8665

Jiangxi Key Laboratory of Green General Aviation Power, School of Power and Energy, Nanchang Hangkong University, Nanchang, Jiangxi 330063, P. R. China

Search for more papers by this author

Kun Guo

https://orcid.org/0000-0001-9805-8152

Jiangxi Key Laboratory of Green General Aviation Power, School of Power and Energy, Nanchang Hangkong University, Nanchang, Jiangxi 330063, P. R. China

Search for more papers by this author

, and

Pu Mao

https://orcid.org/0000-0002-0788-9397

School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang, Jiangxi 330063, P. R. China

Search for more papers by this author

https://doi.org/10.1142/S2010135X24500322Cited by:0 (Source: Crossref)

Abstract

Piezocatalysis is an emerging approach for degrading organic dye. However, the limited availability of ultrasonic resources in nature restricts its practical application. Our proposed peak flow kinetic energy piezocatalytic strategy, based on a “waterfall flow” model, aims to simulate the piezocatalytic degradation of pollutants in nature. This innovative strategy can enhance degradation efficiency by adjusting the flow rate and drop height. When 140mL of rhodamine B (RhB) dye solution flows at a rate of 1000mL/min from a height of 48cm and impacts a 3 cm diameter BaTiO₃ nanowires/PVDF piezoelectric composite film, a degradation rate of 90% can be achieved within 120min. This rapid degradation is primarily attributed to the efficient conversion of kinetic energy into impact force as the water falls, which triggers the generation of piezopotential in the composite film. This, in turn, drives the separation and transmission of electron–hole pairs, leading to the promotion of reactive oxygen species (ROS) generation and facilitating fast organic dye degradation. The pulsating nature of the impact force ensures a continuous generation of ROS. This approach is poised to advance piezocatalysis for the degradation of organic dyes in natural environments and presents a novel method for wastewater treatment.

Keywords:

1. Introduction

Organic dyes, widely utilized in textiles, papermaking, and personal care products, pose significant risks to ecosystems and human health when discharged into wastewater, thus making them a central focus of ongoing water pollution control efforts.^1,2,3 Currently, the primary treatment methods for organic dye pollution encompass physical, chemical, and biological approaches.^4,5,6 Typically, these methods necessitate specialized large-scale equipment and are susceptible to secondary pollution. Furthermore, the complex molecular structure of dyes and the potential generation of more toxic intermediate products during the degradation process highlight the urgent need for efficient and environmentally friendly treatment methods.^7,8 Piezocatalysis is an emerging catalytic technology that effectively utilizes ultrasound to induce mechanical force to facilitate electron–hole oxidation–reduction reactions, leading to the generation of reactive oxygen species (ROS) like hydroxyl radicals (•OH), superoxide radicals (•O $_{2}^{-}$ ), and singlet oxygen (¹O $_{2})$ .^9,10,11,12 This technology has garnered considerable attention and research interest for its direct degradation of organic dyes.^13,14

Piezocatalysis combines the effects of piezoelectricity and catalysis, utilizing the positive piezoelectric effect to induce polarization and generate a built-in electric field under mechanical stimulation.^15,16,17 The electric field force generated by the built-in electric field drives electron–hole pairs to separate and move toward the opposite charge polarities of the polarizing field, followed by the screening of heterogeneous charges outside the surface and redox reactions to generate homogeneous ROS.^18,19 ROS can effectively decompose organic macromolecules into various nontoxic small molecules, achieving efficient purification of rhodamine B (RhB) dye.^20,21,22 For example, when K $_{0.5}$ Na $_{0.5}$ NbO₃ (KNN) powders generate a large amount of •OH under ultrasonic stimulation, it induces efficient degradation of RhB dye.¹⁷ Sulfur-doped graphdiyne (SGDY) nanosheets can generate a large amount of ROS through ultrasonic action. These ROS then combine with RhB macromolecules and decompose them into several nontoxic small molecules, thereby achieving efficient degradation of organic dye.²² The powder-type piezocatalysts mentioned above are well known for their exceptional ability to generate ROS, attracting significant attention and research efforts.²³ Nevertheless, their limited recyclability hinders their widespread application. In contrast, ferroelectric polymers such as polyvinylidene fluoride (PVDF) film exhibit better recyclability.

PVDF is extensively utilized as an organic piezoelectric material because of its relatively high piezoelectricity generated from the $β$ -phase, exceptional chemical stability, flexibility, and the potential for exhibiting high piezocatalytic activity.^24,25 Based on the theories of piezoelectronics and piezophotonics,^26,27 it is known that the ability to generate ROS through piezocatalysis is correlated with the piezoelectric coefficient ( $d_{33}$ ) and it usually improves as $d_{33}$ increases.^19,28 Nevertheless, the application of PVDF as a practical piezocatalysis device is limited by its low $d_{33}$ . Enhancing the piezocatalytic activity of PVDF can be effectively achieved by increasing the content of the $β$ -phase in the material or by adding inorganic fillers with a high $d_{33}$ . For instance, the addition of graphene can promote the formation of more $β$ -phase in PVDF, thereby enhancing the film’s piezoelectricity and ability to generate ROS for efficient organic dye degradation.²⁹ Additionally, incorporating piezoelectric ceramic particles such as Ba $_{0.85}$ Ca $_{0.15}$ Zr $_{0.1}$ Ti $_{0.9}$ O₃ (BCZTO) results in superior piezoelectricity and enhanced dye degradation capability in the film.³⁰

It is noteworthy that the primary method of inducing external mechanical force for piezocatalysis is ultrasonic vibration. This method relies on the powerful impact force generated during the collapse of cavitation bubbles to stimulate material deformation, thereby inducing piezocatalytic effects. Despite the strong ability of ultrasonic cavitation effect to induce piezocatalytic reactions, this method still encounters significant challenges in practical applications. For example, thermal effects and potential thermochemistry resulting from ultrasonic vibrations may impact both carrier transport efficiency and actual catalytic efficiency.^31,32 Furthermore, the limited availability of ultrasonic resources in nature severely hinders the practical application of piezocatalysis. Hence, there is an urgent need for a green and widely accessible mechanical force, such as flowing water, to stimulate the piezocatalytic effect and advance its application in nature. For instance, the natural phenomenon of “waterfall flow” generates powerful kinetic energy during descent, rapidly converting it into impact force, which could potentially be harnessed to stimulate piezocatalytic reactions.

In this study, we draw inspiration from the common natural occurrence of “waterfall flow” and propose utilizing the kinetic energy generated by falling water to activate a piezoelectric composite film for piezocatalytic activity in green dye degradation (Fig. 1). BaTiO₃ nanowires (BT NWs) are utilized as fillers, and PVDF serves as the polymer matrix in the preparation of a high-piezoelectric composite film. The enhancement of piezocatalytic efficiency is attained by adjusting the flow rate and drop height of the dye solution. Our findings indicate that when dye solution is released at a flow rate of 1000mL/min from a height of 48cm, it triggers the maximum piezocatalytic activity, resulting in a 90% purification rate for 140mL of RhB wastewater within 120min. The experimental outcomes showcase an efficient degradation of organic dye with outstanding recyclability. This research not only introduces a novel green and cost-effective approach to enhance the utilization of piezocatalysis in natural settings, but also enhances our comprehension of the fundamental mechanisms underlying piezocatalysis.

Fig. 1. Peak flow energy piezocatalytic degradation of organic dye.

2. Experimental

2.1. Materials

Rhodamine B, benzoquinone (BQ, 99%), isopropyl alcohol (IPA, ≥ 99.5%), and ethylenediamine tetraacetic acid disodium salt (EDTA–2Na, ≥ 99%) were supplied from Sinopharm Chemical Reagent Co., Ltd. Sodium hydroxide (NaOH, 99.99%), tetrabutyl titanate ([CH₃(CH $_{2})_{3}$ O]₄Ti, ≥ 99%), Ba(OH) $_{2} \cdot 8$ H₂O (98%), N,N-dimethylformamide (DMF, 99.9%), and polyvinylidene fluoride were purchased from Aladdin. All chemicals were actually analytical grade reagents without further purification.

2.2. Fabrication of BT NWs and BT NWs/PVDF piezoelectric composite film

Given the established BT NWs synthesis method, a two-step hydrothermal procedure was employed to produce high-aspect-ratio BT NWs, as outlined in our previous work for experimental specifics.³³ Following this, the pre-synthesized BT NWs were proportionally weighed and placed in centrifuge tubes (PVDF amounts of 1, 2, 3, 4, and 5wt.%), then uniformly dispersed by mixing with 2.5g DMF solvent. Simultaneously, 0.3g of PVDF powders were weighed and added into 5 g DMF, mixed with the dispersion, and stirred at 60^∘C for 12h for polymer dissolution, and thorough blending of inorganic fillers into the polymer solution. Subsequently, a simple casting process was employed to fabricate a high-piezoelectric BT NWs/PVDF composite film.

2.3. Characterization

The microstructure of BT NWs was examined using an X-ray diffractometer (XRD, D8ADVANCE by Bruker, Germany). The surface morphology of the BT NWs/PVDF piezoelectric composite film was investigated with a field-emission scanning electron microscope (FE-SEM, Nova NanoSEM 450 by FEI, USA). The piezoelectric responses of both the PVDF film and the BT NWs/PVDF piezoelectric composite film were assessed through piezoresponse force microscopy (PFM, model MFP-3D by Asylum Research, USA). The degradation of dye was monitored using a UV–visible spectrophotometer (UV-9000 by METASH, Shanghai, China) with the absorption peak of RhB observed at 554nm.

2.4. Catalytic performance experiment

In this experiment, a peristaltic pump drives the circulation of wastewater, harnessing the kinetic energy produced as water descends from a height to initiate piezocatalytic reactions, resulting in the generation of ROS for pollutant degradation. The methodology is grounded on the “waterfall flow” model and hydrodynamic principles. More precisely, the kinetic energy engendered by the descending water is transformed into impact force to activate the film’s generation of piezopotential, facilitating the parting of electron–hole pairs and stimulating the piezocatalytic effect. The impact force magnitude during this process adheres to the following theoretical formula :

F = Δ P / Δ t, <math display="block" altimg="eq-00032.gif"><mi>F</mi><mo>=</mo><mi mathvariant="normal">Δ</mi><mi>P</mi><mo stretchy="false">/</mo><mi mathvariant="normal">Δ</mi><mi>t</mi><mo>,</mo></math> (1)

where F is the impact force,

$Δ P$ is the change in current momentum, and

$Δ t$ is the time interval. The primary influencing factors in this strategy are the drop height and water flow rate. Prior to the peak flow energy piezocatalytic degradation of dye, the piezocatalytic activity of the prepared piezoelectric composite films was initially evaluated using an ultrasonic cleaner operating at 180

W and 40

kHz frequency. The organic–inorganic piezoelectric composite film was then sectioned into 1.5

cm rectangles for testing. Following the establishment of adsorption–desorption equilibrium, the piezoelectric composite film was placed in a test tube containing 10

mL of RhB (5

mg/L) organic dye to evaluate the RhB degradation performance. Experimental setups with drop heights of 48, 24, 16, and 12

cm were designed and constructed to better replicate and validate the proposed strategy [Figs. 2(a)–2(d)]. This design allows for the examination of fluid kinetic piezocatalytic performances at different drop heights.

Fig. 2. Degradation performance tests at different drop heights: (a) 48cm, (b) 24cm, (c) 16cm, and (d) 12cm.

Considering that the strategy is also related to water flow rate, flow rates of 700, 1000, and 1300mL/min were adjusted, with the corresponding flow rate experimental setups shown in Figs. 3(a)–3(c). Then, multiple piezoelectric composite films with diameters of 6.5cm and 3cm were placed in different flow vessels for subsequent experimental testing of the peak flow energy piezocatalysis. To eliminate physical adsorption interference, all experimental materials were immersed in RhB solution for 12h before the experiment to achieve adsorption–desorption equilibrium. To avoid the interference of photocatalysis, the entire experiment was conducted in the dark.

Fig. 3. Degradation performance tests at different water flow rates: (a) 700mL/min, (b) 1000mL/min, and (c) 1300mL/min.

2.5. Detection of free radicals experiment

The trapping experiment is primarily used to identify the main active radicals in the catalytic reaction. Prior to the experiment, equimolar amounts of ethylenediamine tetraacetic acid disodium salt, benzoquinone, and isopropyl alcohol were added separately to the RhB solution as scavengers or inhibitors of holes ( $h^{+}$ ), •O $_{2}^{-}$ , and •OH, respectively.

2.6. Finite element simulation

To quantitatively analyze the feasibility of this piezocatalytic strategy, the pressure distribution and local voltage distribution of the bottom piezoelectric composite film were simulated under various flow rates and drop heights using finite element simulation software, in accordance with the actual experimental conditions. In this study, the actual experiments were simplified into a single two-dimensional model. The flow was characterized by turbulence, and both the phase field module and the solid physics piezoelectric module were employed to simulate the magnitudes of the water impact force and the piezopotential, respectively. Here, the sizes of the flow vessels and the drop heights are consistent with the actual experimental variables. The bottom diameter of the flow vessel is 30cm, and the diameter of the outlet pipe is 1.2cm, with a length of 1cm. The height of the outlet pipe orifice from the bottom of the flow vessel is the drop height, which is consistent with the actual experiment. The velocity flow is used to simulate the action of the water flow, and the velocity values are calculated based on the actual experimental flow rates.

3. Results and Discussion

First, the crystallographic structure of the synthesized BT NWs was assessed using XRD [Fig. 4(a)]. The X-ray diffraction pattern displayed distinct and sole perovskite diffraction peaks, affirming the successful fabrication of BT NWs. Subsequent SEM analysis depicted BT NWs with a notable aspect ratio uniformly dispersed within the PVDF matrix, affirming the successful production of piezoelectric composite film [Fig. 4(b)]. Additionally, it was observed that BT NWs were uniformly distributed on both the inner and outer sides of the polymer matrix, which not only was expected to enhance piezoelectricity of the polymer composite but also served as fillers to enhance the toughness of the polymer, effectively improving the recyclability of the piezocatalyst.

Here, we also assessed the piezoelectric responsiveness of PVDF and BT NWs/PVDF piezoelectric composite film using PFM [Figs. 5(a)–5(d)]. The piezoelectric amplitude plots shown in Figs. 5(a) and 5(c) demonstrate that the piezoelectric response signal of the fabricated BT NWs/PVDF composite is greater than that of pure PVDF, in accordance with the formula

A = d 33 V ac Q, <math display="block" altimg="eq-00060.gif"><mi>A</mi><mo>=</mo><msub><mrow><mi>d</mi></mrow><mrow><mn>3</mn><mn>3</mn></mrow></msub><msub><mrow><mi>V</mi></mrow><mrow><mstyle><mtext mathvariant="normal">ac</mtext></mstyle></mrow></msub><mi>Q</mi><mo>,</mo></math> (2)

where A,

$d_{33}$ ,

$V_{ac}$ , and Q represent the piezoelectric amplitude, piezoelectric coefficient, alternating voltage applied to the sample through the conductive cantilever tip, and quality factor, respectively. It can be observed that as the piezoelectric amplitude increases, the piezoelectric coefficient also increases, thereby enhancing the piezoelectric response capability. Furthermore, the phase reversal angle depicted in Fig. 5(b) is substantially larger than that in Fig. 5(d), providing strong evidence that BT NWs/PVDF piezoelectric composite film exhibits superior piezoelectric response capabilities in comparison to the pure PVDF film. This phenomenon may originate from the increased polarization and ordering of PVDF molecular chains upon the addition of BT NWs,³⁴ and also shows that BT NWs/PVDF may have more excellent piezocatalytic activity.

Fig. 5. PFM tests of the prepared BT NWs/PVDF and PVDF samples: (a), (b) amplitude and phase images of BT NWs/PVDF sample and (c), (d) amplitude and phase images of pure PVDF sample.

Based on previous studies, it is known that piezocatalytic activity typically increases with the increase in the piezoelectric coefficient $d_{33}$ .^19,35 Therefore, we first utilized ultrasound to verify the piezocatalytic activity of the prepared BT NWs/PVDF piezoelectric composite film catalyst. From the data in Fig. S1 of Supplementary Information, it can be observed that with the increase in the doping level of BT NWs, the ability of piezocatalysis to degrade RhB exhibits a trend of initially increasing and then decreasing. The degradation performance of pollutants is optimal at a doping level of 3wt.%. The analysis shows that the enhancement of the piezocatalytic performance of the piezoelectric composite film after doping with BT NWs is attributed to the improvement in piezoelectricity and the increase in active sites. Specifically, BT NWs as ceramic fillers can serve as nucleating agents for the $β$ -phase crystal structure,³⁶ while also acting as nanoscale polar dielectrics, thereby increasing the interfacial area and consequently enhancing polarization effects and charge transfer. Additionally, the presence of a high number of active sites and a large specific surface area of BT NWs on the surface of PVDF leads to an increase in the density of active sites, strengthening reaction centers and enhancing catalytic activity. Nevertheless, further heightened doping levels may result in excessive interfacial effects between BT NWs and PVDF chains, leading to nonuniform local charge distribution. This phenomenon can disrupt the original $β$ -phase structure of PVDF chains, ultimately diminishing the piezoelectric performance and piezocatalytic activity of the piezoelectric composite film. Moreover, excessive doping can cause filler aggregation, reducing the effective specific surface area of active sites.

Therefore, we chose a 3wt.% doping level to fabricate organic–inorganic piezoelectric composite film for subsequent validation of the experimental strategy for peak flow energy piezocatalysis. Here, after excluding physisorption, we first investigated the effect of drop height on the performance of piezocatalytic degradation. According to Figs. 6(a)–6(d), it is evident that the optimal degradation of RhB occurs with a drop height of 48cm. Subsequently, as the drop height decreases, the piezocatalytic activity gradually diminishes. This can be attributed to the gradual reduction in the impact force of water flow on the bottom of the beaker as the drop height decreases, leading to a decrease in the piezoelectric potential generated by the piezoelectric composite film. This would result in a reduction of the ability to trigger electron–hole pairs separation, thereby weakening the piezocatalytic activity for ROS generation. Furthermore, augmenting the quantity of piezoelectric composite film [Figs. 2(b)–2(d)] marginally improves the degradation of RhB [Figs. 6(b)–6(d)], yet the overall piezocatalytic activity diminishes as the drop height decreases. In conclusion, drop height is a significant factor influencing the piezocatalysis driven by the gravitational potential energy flow of water.

Fig. 6. RhB degradation effects at different drop heights for the same flow rate (1000mL/min): (a) 48cm, (b) 24cm, (c) 16cm, and (d) 12cm.

In addition to drop height, we also investigated the effect of water flow on the piezocatalytic performance. As depicted in Figs. 7(a)–7(c), the piezocatalytic activity for the degradation of RhB increased gradually with higher water flow rate. This can be attributed to the heightened impact force on the bottom with increasing water flow rate, enhancing the piezopotential to facilitate the separation of electron–hole pairs. However, as a freely flowing medium, water flow exhibits an increase in inertia with a higher flow rate, which may result in turbulence and vortices that disrupt the trajectory of the water flow, thus affecting the stable performance of piezocatalysis. Moreover, a high flow rate exacerbates damage to the piezoelectric composite film and has an impact its reusability.

Fig. 7. RhB degradation effects at different flow rates at the same drop height (48cm): (a) 700mL/min, (b) 1000mL/min, and (c) 1300mL/min.

Extensive analysis indicates that the optimal performance for piezocatalytic degradation of RhB is achieved at a water flow rate of 1000mL/min and a drop height of 48cm [Fig. 8(a)]. After six cycles of experiments, the efficiency of piezocatalytic RhB degradation remains above 70% [Fig. 8(b)]. On the one hand, this illustrates the viability of harnessing peak flow energy to drive piezoelectric catalysis strategies. On the other hand, it underscores the exceptional piezoresponse and recyclable properties of the organic–inorganic piezoelectric composite film. It is noteworthy that an increase in drop height ( $> 48$ cm) and water flow rate ( $> 1000$ mL/min) will enhance the separation of electron–hole pairs, induce more carriers to migrate to the opposite surfaces of the material, increase the number of external screening charges, and improve the piezocatalytic activity. However, it can be inferred from Fig. 8(b) that this will exacerbate and expedite damage to the piezoelectric composite film while reducing recyclability. Additionally, based on aerodynamic effects, heightened flow rate and drop height will augment air resistance, leading to the dispersion of water flow patterns and impacting the piezocatalytic activity stability.

Fig. 8. Optimal experimental conditions for flow-driven piezocatalytic degradation of RhB and recycling stability under that condition: (a) optimal flow rate and drop height and (b) recycling stability of RhB degradation.

ROS, such as •OH and •O $_{2}^{-}$ , are one of the strongest aqueous redox species.³⁷ Research suggested that the degradation of pollutants by piezocatalysis benefits from the strong oxidative ability of ROS.¹⁹ To elucidate the piezocatalytic mechanism, we conducted the trapping experiments to identify which free radicals play the major role in the piezocatalytic process. Various radical scavengers were spiked into the RhB solution prior to catalytic degradation experiments, such as IPA, BQ, and EDTA–2Na as the scavengers for •OH, •O $_{2}^{-}$ , and $h^{+}$ , respectively. As shown in Fig. S2, both BQ and IPA additions inhibited the piezocatalytic reaction from proceeding, especially BQ addition significantly decreased the rate of RhB degradation. This suggests that both •O $_{2}^{-}$ and •OH are the primary active species, with •O $_{2}^{-}$ having a more significant impact than •OH. Similarly, the absence of a significant change in degradation rate upon the addition of EDTA–2Na suggests that in this experimental process, $h^{+}$ is not the primary active species.

To further theoretically comprehend the feasibility of the piezocatalytic strategy, we conducted a simulation study using the finite element simulation method to analyze the principal influencing factors in this experimental procedure. First, the impact force on the bottom of the beaker was simulated under different drop heights. As shown in Figs. 9(a)–9(d), it can be observed that the impact force generated by the direct impact of the water flow is the largest, and the impact force gradually decreases to the two ends of the container. The local impact force can reach 521, 495, 366, and 253 Pa, which indicates that as the drop height decreases, the impact force generated by the direct impact of water flow on the bottom of the beaker gradually decreases. This result is consistent with both experimental and theoretical formulae derived.

Fig. 9. Simulations of the magnitude of the impact force on the piezoelectric composite film at the bottom of a beaker due to flowing water with different drop heights at the same flow rate: (a) 48cm, (b) 24cm, (c) 16cm, and (d) 12cm.

According to the triggering mechanism of the piezoelectric effect, it is known that the piezopotential will gradually decrease as the external mechanical force decreases, which is verified in Figs. 10(a)–10(d). These figures show that the local piezopotential of the piezoelectric composite film gradually decreases from 5.82V to 2.81V as the drop height is reduced from 48cm to 12cm, indicating that the magnitude of the impact force is an important factor affecting the magnitude of the piezopotential. The piezopotential, as the driving force for carrier generation and separation, directly influences piezocatalytic activity. Here, at a drop height of 48cm, the impact of water flow can induce the maximum piezopotential on the composite film at the bottom, resulting in the highest piezocatalytic activity. As the piezopotential decreases, the resulting polarization electric field force may not be adequate to trigger the complete separation of electron–hole pairs, leading to a high rate of carrier recombination and a decrease in piezocatalytic activity. Similarly, according to the screening charge theory, a reduction in the number of carriers migrating to the opposite surfaces leads to a corresponding decrease in externally screened charges, resulting in a reduction of the piezocatalytic reaction rate. It is important to note that increasing the usage of piezoelectric composite film [Figs. 2(b)–2(d)] can alleviate the decrease in piezopotential caused by the reduced drop height, but provides only a slight enhancement to the overall piezocatalytic activity, while also increasing the experimental complexity.

Fig. 10. Simulations of piezoelectric composite film piezopotential at the bottom of a beaker with different drop heights of flowing water at the same flow rate: (a) 48cm, (b) 24cm, (c) 16cm, and (d) 12cm.

Here, we also conducted simulations to investigate the impacts of varying water flow rates on both the impact force [Figs. S3(a) and S3(b)] and the magnitude of piezopotential [Figs. S3(c) and S3(d)] of the underlying piezoelectric composite film. As shown in Fig. S3, when the flow rate increases from 700mL/min to 1300mL/min, the maximum water flow impact on the bottom piezoelectric composite film increases from 193Pa to 560Pa, and the piezopotential also increases from 1.8V to 6V. The above phenomenon indicates that as the flow rate increases, the impact force on the bottom piezoelectric composite film and the generated piezopotential will increase with the increase of water flow rate. A higher water flow rate results in greater kinetic energy during the falling process, leading to increased impact force and piezopotential. Consequently, piezocatalytic activity theoretically rises with higher water flow rates, a trend consistent with the experimental findings. However, as the water flow rate increases, flow stability is compromised due to the heightened inertia effect, turbulence, and vortex formation. Moreover, higher water flow rates increase friction resistance with the surrounding environment, disrupt flow morphology, and escalate experimental complexity. Thus, selecting appropriate drop height and water flow rate is critical to optimize piezocatalytic activity and facilitate recycling experiments.

4. Conclusions

In summary, we propose using peak flow energy piezocatalysis as an environmentally friendly method for degrading organic dye. This approach involves converting the kinetic energy produced by water flowing from a height into impact force at the base, thereby triggering piezoelectric composite films to exhibit a piezocatalytic effect. With this technique, a 90% purification rate for 140mL of RhB dye can be achieved within 120min, with the organic dye solution flowing at a rate of 1000mL/min from a height of 48cm. These results demonstrate the viability of this approach for sustainably generating piezocatalytic reactive oxygen species. This study is poised to advance the practical utilization of piezocatalysis, particularly in the breakdown of organic dyes, reducing reliance on the external power sources for alpine water features and water purification, and offering a novel approach to wastewater treatment.

Acknowledgments

This work is supported by the National Natural Science Foundation of China (Grant No. 52162018) and the Science Fund for Distinguished Young Scholars of Jiangxi Province (Grant No. 20224ACB214007).

Supplementary Information

The Supplementary Information are available at: https://www.worldscientific.com/doi/suppl/10.1142/S2010135X24500322.

ORCID

Bing Xie https://orcid.org/0000-0003-2402-064X

Zhiyong Liu https://orcid.org/0000-0003-2044-8665

Kun Guo https://orcid.org/0000-0001-9805-8152

Pu Mao https://orcid.org/0000-0002-0788-9397

References

1. Y. Wen et al., A new nitrogen-rich imine-linked neutral covalent organic framework: Synthesis and high-efficient adsorption of organic dyes, Colloids Surf. A 688, 133661 (2024). Crossref, Google Scholar
2. K. S. Abou-Melha, Effective elimination of Coomassie Brilliant Blue dye from aqueous solutions using Cerium Metal-Organic Frameworks: Synthesis, characterization, and optimization of adsorption process utilizing Box-Behnken design, J. Water Process Eng. 63, 105406 (2024). Crossref, Google Scholar
3. Y. Hong et al., Rational design 2D/3D MoS₂/In₂O₃ composites for great boosting photocatalytic H₂ production coupled with dye degradation, J. Taiwan Inst. Chem. Eng. 146, 104862 (2023). Crossref, Google Scholar
4. F. Duarte et al., New insight about orange II elimination by characterization of spent activated carbon/Fe Fenton-like catalysts, Appl. Catal. B, Environ. 129, 264 (2013). Crossref, Google Scholar
5. R. A. Pereira et al., Carbon based materials as novel redox mediators for dye wastewater biodegradation, Appl. Catal. B, Environ. 144, 713 (2014). Crossref, Google Scholar
6. Y. P. Chen et al., Research progress of sewage treatment technology, Adv. Mater. Res. 726–731, 2576 (2013). Crossref, Google Scholar
7. C. Porwal et al., Piezocatalysis dye degradation using SrO-Bi₂O₃-B₂O₃ glass-ceramics, ACS Appl. Eng. Mater. 1, 295 (2023). Crossref, Google Scholar
8. R. Jiang et al., Insights into a CQD-SnNb₂O₆/BiOCl Z-scheme system for the degradation of benzocaine: Influence factors, intermediate toxicity and photocatalytic mechanism, Chem. Eng. J. 374, 79 (2019). Crossref, Google Scholar
9. Y. Wen et al., Two birds with one stone: Cobalt-doping induces to enhanced piezoelectric property and persulfate activation ability of ZnO nanorods for efficient water purification, Nano Energy 107, 108173 (2023). Crossref, Google Scholar
10. S. D. Mahapatra et al., Piezoelectric materials for energy harvesting and sensing applications: Roadmap for future smart materials, Adv. Sci. 8, 2100864 (2021). Crossref, Google Scholar
11. J. Liao et al., Boosting piezo-catalytic activity of KNN-based materials with phase boundary and defect engineering, Adv. Funct. Mater. 33, 2303637 (2023). Crossref, Google Scholar
12. R. Jiang et al., Lattice distortion SnS₂ piezoelectric self-Fenton system for efficient degradation and detoxification of pollutants, npj Clean Water 6, 79 (2023). Crossref, Google Scholar
13. S. Tu et al., Piezocatalysis and piezo-photocatalysis: Catalysts classification and modification strategy, reaction mechanism, and practical application, Adv. Funct. Mater. 30, 2005158 (2020). Crossref, Google Scholar
14. B. Liang et al., Efficient piezocatalytic properties of Na $_{0.5}$ Bi $_{0.5}$ TiO₃ nanoparticles for dye degradation and hydrogen peroxide production, J. Adv. Dielectr. (2024), https://doi.org/10.1142/S2010135X24500061. Link, Google Scholar
15. J. M. Wu et al., Piezo-catalytic effect on the enhancement of the ultra-high degradation activity in the dark by single- and few-layers MoS₂ nanoflowers, Adv. Mater. 28, 3718 (2016). Crossref, Google Scholar
16. X. Xue et al., Piezo-potential enhanced photocatalytic degradation of organic dye using ZnO nanowires, Nano Energy 13, 414 (2015). Crossref, Google Scholar
17. X. Wang et al., Lead-free (K, Na)NbO₃ piezocatalyst with superior piezocatalysis and large-scale production, Adv. Funct. Mater. 34, 2313662 (2024). Crossref, Google Scholar
18. B. Yuan et al., Enhanced piezocatalytic performance of (Ba,Sr)TiO₃ nanowires to degrade organic pollutants, ACS Appl. Nano Mater. 1, 5119 (2018). Crossref, Google Scholar
19. Y. Wang et al., Ultrasonic activation of inert poly(tetrafluoroethylene) enables piezocatalytic generation of reactive oxygen species, Nat. Commun. 12, 3508 (2021). Crossref, Google Scholar
20. C. Porwal et al., Photocatalytic dye degradation using lithium borate-bismuth tungstate glass-ceramics, Ceram. Int. 49, 32808 (2023). Crossref, Google Scholar
21. R. Jiang et al., Facet-dependent photoactivity of Mn₃O₄/BiOCl for naproxen detoxication: Strengthening effect of Mn valence cycle, Appl. Catal. B, Environ. 299, 120672 (2021). Crossref, Google Scholar
22. J. Zhang et al., Piezoelectric enhanced peroxidase-like activity of metal-free sulfur doped graphdiyne nanosheets for efficient water pollutant degradation and bacterial disinfection, Nano Today 43, 101429 (2022). Crossref, Google Scholar
23. D. Mondal et al., Recent advances in piezocatalytic polymer nanocomposites for wastewater remediation, Dalton Trans. 51, 451 (2022). Crossref, Google Scholar
24. X. Liao et al., Enhanced piezocatalytic reactive oxygen species production activity and recyclability of the dual piezoelectric Cu₃B₂O₆/PVDF composite membrane, ACS Appl. Mater. Interfaces 15, 1286 (2023). Crossref, Google Scholar
25. T. D. Raju et al., Polyvinylidene fluoride/ZnSnO₃ nanocube/Co₃O₄nanoparticle thermoplastic composites for ultrasound-assisted piezo-catalytic dye degradation, ACS Appl. Nano Mater. 3, 4777 (2020). Crossref, Google Scholar
26. Z. L. Wang, Piezopotential gated nanowire devices: Piezotronics and piezo-phototronics, Nano Today 5, 540 (2010). Crossref, Google Scholar
27. W. Wu and Z. L. Wang, Piezotronics and piezo-phototronics for adaptive electronics and optoelectronics, Nat. Rev. Mater. 1, 16031 (2016). Crossref, Google Scholar
28. K. Wang et al., Ternary BaCaZrTi perovskite oxide piezocatalysts dancing for efficient hydrogen peroxide generation, Nano Energy 98, 107251 (2022). Crossref, Google Scholar
29. T.-H. Huang et al., Piezocatalytic property of PVDF/graphene self-assembling piezoelectric membrane for environmental remediation, Chem. Eng. J. 487, 150569 (2024). Crossref, Google Scholar
30. M. Sharma et al., Piezocatalysis in ferroelectric Ba $_{0.85}$ Ca $_{0.15}$ Zr $_{0.1}$ Ti $_{0.9}$ O₃/polyvinylidene difluoride (PVDF) composite film, J. Appl. Phys. 130, 085107 (2021). Crossref, Google Scholar
31. W. Ma et al., Synthesis and characterization of ZnO-GO composites with their piezoelectric catalytic and antibacterial properties, J. Environ. Chem. Eng. 10, 107840 (2022). Crossref, Google Scholar
32. L. Lu et al., Highly efficient sono-piezo-photo synergistic catalysis in bismuth layered ferroelectrics via finely distinguishing sonochemical and electromechanochemical processes, J. Materiomics 8, 47 (2022). Crossref, Google Scholar
33. B. Xie et al., Largely enhanced ferroelectric and energy storage performances of P(VDF-CTFE) nanocomposites at a lower electric field using BaTiO₃ nanowires by stirring hydrothermal method, Ceram. Int. 42, 19012 (2016). Crossref, Google Scholar
34. J. Jiang et al., Flexible piezoelectric pressure tactile sensor based on electrospun BaTiO₃/poly(vinylidene fluoride) nanocomposite membrane, ACS Appl. Mater. Interfaces 12, 33989 (2020). Crossref, Google Scholar
35. R. Xu et al., Lattice strain engineered reactive oxygen species generation of NaNbO₃ ferroelectric, Nano Energy 127, 109738 (2024). Crossref, Google Scholar
36. V. Fathollahzadeh and M. Khodaei, Effect of BaTiO₃ nanoparticles contents on piezoelectric response of PVDF-BaTiO₃ nanocomposite, J. Ultrafine Grained Nanostructured Mater. 56, 157 (2023). Google Scholar
37. T. Zhou et al., An AIE-active conjugated polymer with high ROS-generation ability and biocompatibility for efficient photodynamic therapy of bacterial infections, Angew. Chem., Int. Ed. 59, 9952 (2020). Crossref, Google Scholar

Online Ready

Metrics

Downloaded 115 times

History

Received 24 September 2024

Revised 8 November 2024

Accepted 13 November 2024

Published: 30 December 2024

Information

This is an Open Access article published by World Scientific Publishing Company. It is distributed under the terms of the Creative Commons Attribution 4.0 (CC BY) License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Keywords

PDF download