Highly Efficient Flexocatalysis of Two-Dimensional Semiconductors

Non-piezoelectric SiO2 amorphous nanomaterials for highly tribocatalytic water purification

Being widely available in the earth's rock layers, SiO2 is among the earth's most thoroughly distributed natural mineral resources. Here, non-piezoelectric amorphous SiO2 mineral nanoparticles have been experimentally designed for efficient tribocatalytic dye degradation under mechanical friction provided by 400-1200 rpm low-velocity stirring. The friction between the catalyst surface and the stirring rod leads to the generation of positive and negative charges, which react with hydroxide and oxygen, respectively, in the dye solution to produce some active substances, resulting in tribocatalytic organic dye degradation. After being mechanically stirred at 1000 rpm for 6 h using amorphous SiO2 mineral nanoparticle catalysts, ∼95.2% of Rhodamine B dye can be obviously degraded. Radical trapping experiments show that ˙OH and ˙O2- are the main active substances. Furthermore, increasing the contact area or the friction contact interface's roughness is helpful for enhancing the tribocatalytic performance. After 3 recycling cycles, the SiO2 nanoparticles can still degrade ∼89.2% of RhB dye. These low-cost SiO2 mineral nanoparticles, with the advantage of being widely distributed, have the potential to harvest common environmental mechanical friction energy for the purpose of organic pollutant degradation.

Unveiling Mechanically Driven Catalytic Processes: Beyond Piezocatalysis to Synergetic Effects

Mechanically driven catalysis (MDC) has emerged as an effective strategy for environmental remediation, renewable energy conversion, and cancer therapy; this functions by converting mechanical forces to drive catalytic reactions. This review examines four primary mechanisms, namely, piezocatalysis, flexocatalysis, tribocatalysis, and sonocatalysis, each involving specific catalytic pathways for harnessing mechanical energy at the nanoscale. However, significant challenges arise in decoupling the effects related to each individual mechanism in order to better understand and manipulate their synergies. In this review, the fundamental principles underpinning MDC are systematically interpreted. Beyond mechanistic insights, recent advancements in performance enhancement strategies for these catalysts are highlighted. Potential applications using these mechanistic approaches in environmental remediation (pollutant and antibiotic degradation and microbial disinfection), renewable energy conversion (hydrogen production and greenhouse gas conversion), and biomedical treatments (particularly cancer therapy) are discussed. Finally, the mechanistic synergies and limiting factors are explored, addressing challenges related to the overlooked combined effects of ultrasound as the activation source, complexities in mechanical force interactions at the nanoscale, and the need for targeted application strategies. Additionally, the industrial potential of these catalytic processes with consideration to scalability and practical deployment is evaluated. While challenges remain, this review provides a roadmap for advancing mechanically driven catalyst design and implementation toward real-world applications, offering potential into its future trajectory and transformative impact across numerous fields.

Boosting hydrogen evolution via flexoelectric catalysis in gradient F-doped hydroxyapatite nanowires

The emergence of flexoelectric effect, which refers to the linear electromechanical coupling between strain gradient and charge polarization in a wide range of materials, suggests a new catalytic mechanism to activate chemical bonds and reactions. Although pioneering studies have shown the remarkable potential for flexoelectric catalysis in a few scenarios, the lack of green, cheap, bio-compatible, and high-efficiency flexoelectric catalysts acts as a major barrier to its expanding applications. In this study, we report the effective design of a high-performance flexoelectric catalyst by simultaneous structural and compositional engineering on hydroxyapatite, a ubiquitous mineral and a well-known biomaterial. By synergizing atomic-scale and nanoscale strain gradients (which are respectively induced by surface lattice doping and geometry engineering) in F-doped hydroxyapatite nanowires (F-HAP NWs), the flexoelectric response together with the catalytic performance of the material are drastically improved, leading to a high hydrogen generation rate (322.7 μmol g-1 h-1) in pure water. The findings highlight the potential of F-HAP NWs in flexoelectric catalysis and offer new insights into mechanocatalytic and electrochemical processes in biological systems.

Flexocatalytic Hydrogen Generation and Organics Degradation by Nano SrTiO3

Flexocatalysis, a groundbreaking approach in mechanocatalysis, overcomes the material limitations imposed by the symmetry requirements of piezocatalysis, enabling a broader range of materials to generate free radicals through mechano-catalytic reactions. This method not only offers an eco-friendly pathway for green hydrogen production via water splitting but also facilitates the use of biocompatible materials in health diagnostics and treatments. In this study, the flexocatalytic activity of centrosymmetric SrTiO3 (STO) nanopowders is demonstrated, achieving notable hydrogen evolution (1289.53 µmol g-1 h-1 in pure water) and efficient organic dye degradation (≈94%). The mechanism is driven by electric polarization generated under non-uniform strain, which is strongly enhanced with particle size reduction, effectively linking flexoelectricity to superior electrochemical performance. The findings highlight the potential of flexocatalysis to revolutionize hydrogen production and broaden the range of materials for catalytic applications, paving the way for innovative energy-harvesting technologies.

Flexocatalysis: Regulating peroxymonosulfate activation by flexoelectricity

Challenges related to energy shortages and environmental pollution are driving extensive research in catalysis. Flexocatalysis, which extends flexoelectricity to mechanocatalysis, is a promising mechanism for catalytic processes. Owing to its size-dependent effects, flexoelectricity has become particularly significant and plays a dominant regulatory role in chemical reactions within nanocatalysis. In this study, we integrated flexocatalysis with peroxymonosulfate (PMS) activation for efficient water purification. The simulation results show that flexoelectric polarization can induce a strong flexoelectric field in δ-MnO2 nanosheets. This built-in electric field subsequently drives the migration of electrons and holes to the reaction interface, thereby activating PMS and promoting rapid generation of reactive species for the degradation of organic pollutants. At low concentrations of flexoelectric catalysts, we achieved excellent degradation efficiency that was 6.6 times greater than that obtained through the thermal activation of PMS. This study demonstrated that flexoelectricity can function as a switch for PMS activation and offers a promising approach for sustainable water remediation.

Dynamic regulation of ferroelectric polarization using external stimuli for efficient water splitting and beyond

Establishing and regulating the ferroelectric polarization in ferroelectric nano-scale catalysts has been recognized as an emerging strategy to advance water splitting reactions, with the merits of improved surface charge density, high charge transfer rate, increased electronic conductivity, the creation of real active sites, and optimizing the chemisorption energy. As a result, engineering and tailoring the ferroelectric polarization induced internal electric field provides significant opportunities to improve the surface and electronic characteristics of catalysts, thereby enhancing the water splitting reaction kinetics. In this review, an interdisciplinary and comprehensive summary of recent advancements in the construction, characterization, engineering and regulation of the polarization in ferroelectric-based catalysts for water splitting is provided, by exploiting a variety of external stimuli. This review begins with a detailed overview of the classification, benefits, and identification methodologies of the ferroelectric polarization induced internal electric field; this offers significant insights for an in-depth analysis of ferroelectric-based catalysts. Subsequently, we explore the underlying structure-activity relationships for regulating the ferroelectric polarization using a range of external stimuli which include mechanical, magnetic, and thermal fields to achieve efficient water splitting, along with a combination of two or more fields. The review then highlights emerging strategies for multi-scale design and theoretical prediction of the relevant factors to develop highly promising ferroelectric catalysts for efficient water splitting. Finally, we present the challenges and perspectives on the potential research avenues in this fascinating and new field. This review therefore delivers an in-depth examination of the strategies to engineer the ferroelectric polarization for the next-generation of water electrolysis devices, systems and beyond.

High-Performance Piezotronic Devices

The interface phenomena and regulation mechanisms of semiconductor devices are crucial for their applications in the fields of electronics and optoelectronics. The piezotronic effect utilizes the strain-induced piezoelectric polarization at interfaces to regulate the interface energy band and carrier transport, so that the response current of the piezotronic device can change exponentially with small changes of stress/strain, showing high sensitivity. In recent years, in-depth studies of piezotronic effect regarding material, structure, and interface have largely enhanced the piezotronic device's performance; these investigations can also provide guidance for emerging interface engineering by polarizations like the flexotronic effect. This paper reviews the establishment and development of piezotronics and focuses on the latest research achievements in the field regarding material modification, structural design, and interface engineering, so as to provide guidance for the investigation and development of high-performance piezotronic devices. In the end, the paper points out the current challenges of piezotronic devices in practical applications and gives some outlooks for future development in this field.

Self-Poled Bismuth Ferrite Thin Film Micromachined for Piezoelectric Ultrasound Transducers

Piezoelectric micromachined ultrasound transducers (pMUTs), especially those using lead-free materials, are crucial next-generation microdevices for precise actuation and sensing, driving advancements in medical, industrial, and environmental applications. Bismuth ferrite (BiFeO3) is emerging as a promising lead-free piezoelectric material to replace Pb(Zr,Ti)O3 in pMUTs. Despite its potential, the integration of BiFeO3 thin films into pMUTs has been hindered by poling issues. Here, a BiFeO3 heterostructure compositionally downgraded with Gd doping is developed to introduce compressive strain, resulting in strong self-poling. Utilizing a large-area self-poled thin film over an entire 6-inch wafer, a pMUT with a 6 × 6 array at the device level is designed and evaluated. At a resonant frequency of 21 kHz, the dynamic vibration displacement can reach 24.0 nm. At 500 Hz, far below the resonant frequency of 21 kHz, the pMUT also displays sensitive converse piezoelectric response, even at a high temperature of 200 °C. This work represents a significant breakthrough in lead-free BiFeO3 thin film for practical sensing applications, paving the way for the transformation of macro-transducers into next-generation functional microdevices.

Tunable WSe2-MoSe2 Lateral Heterojunction Photodetector Based on Piezoelectric and Flexoelectric Effects

Two-dimensional transition metal dichalcogenides (TMDs) with piezoelectric effects are ideal materials for future wearable devices. While enhancing the piezoelectric performance by forming vertical heterojunctions, shortcomings such as contamination at the heterojunction interface and limited built-in electric field width have been noticed. In this work, a lateral heterojunction of monolayer WSe2-MoSe2 with type-II band alignment was employed to amplify the electromechanical optoelectronic efficiency. The considerable built-in field width (BFW) in the lateral heterojunction facilitates rapid separation of carriers. The lattice mismatch induced a flexoelectric effect during the lateral heterojunction growth. The flexoelectric and piezoelectric effects under external strain can regulate the photodetector performance of the device. Under the compressive strain of -0.93%, the photocurrent increased 9.1 times compared to the tensile strain of 0.47%. Flexoelectric effect can reduce the dark current under no external strain. This work reveals the roles of flexoelectric and piezoelectric effects in enhancing photoelectric conversion, suggesting lateral heterojunction devices may be applied in the field of flexible low-light detection.

Observation of Ferroelectricity in Carbapenem Intermediates Enables Reactive Oxygen Species Generation by Ultrasound

Organic ferroelectrics show great applications in the fields of biomedicine, including disease treatment, biosensors, and tissue engineering. Organosilicon pharmaceutical intermediates generally include chiral centers and have satisfying biosafety, biocompatibility, or even biodegradability, which provide versatile platforms for the design of ferroelectricity. However, their academic values in ferroelectricity have long been long overlooked. Here, we demonstrated the ferroelectric properties of 4-acetoxy-azacyclic butanone (4-AA), a key synthetic organosilicon-based intermediate of carbapenem drugs. This compound undergoes a 222F2-type ferroelectric-ferroelastic phase transition at 326 K. As an organic piezoelectric material, 4-AA can produce reactive oxygen species when subjected to ultrasonic vibrations. Combined with its desirable biocompatibility, this material may contribute to antimicrobial and wound healing, tumor treatment, etc. This work will provide inspiration for the discovery of multifunctional biomedical ferroelectric materials as well as their related application prospects.

Twin Boundaries-Induced Centrosymmetric Breaking of Hollow CaTiO3 Nanocuboids for Piezocatalytic Hydrogen Evolution

Piezocatalysis, a transformative mechanochemical energy conversion technique, has received considerable attention over the past decade for its role in processes such as hydrogen evolution from water. Despite notable progress in the field, challenges remain, particularly in the areas of limited piezocatalysis efficiency and limited availability of materials requiring a non-centrosymmetric structure. Here, a pioneering contribution is presented by elucidating the piezocatalytic properties of hollow CaTiO3 nanocuboids, a centrosymmetric material with a nominally nonpolar state. Remarkably, CaTiO3 nanocuboids exhibit an impressive hydrogen production rate of 3.44 mmol g-1 h-1 under ultrasonic vibrations, surpassing the performance of the well-established piezocatalyst BaTiO3 (2.23 mmol g-1 h-1). In contrast, commercial CaTiO3 nanoparticles do not exhibit piezocatalytic performance. The exceptional performance of hollow CaTiO3 nanocuboids is attributed to the abundance presence of twin boundaries on the {110} facet within its crystal structure, which can impart significant polarization strength to CaTiO3. Extending the investigation to other centrosymmetric materials, such as SrZrO3 and BaZrO3, the experimental results also demonstrate their commendable properties for piezocatalytic hydrogen production from water. This research underscores the significant potential of centrosymmetric materials in piezocatalysis.

Mechanocatalytic Hydrogen Generation in Centrosymmetric Barium Dititanate

Novel phase of nano materials that break the traditional structural constraints are highly desirable, particularly in the field of mechanocatalysis, offering versatile applications ranging from energy to medical diagnosis and treatment. In this work, a distinct layered barium dititanate (BaTi2O5) nanocrystals using a pH-modulated hydrothermal method is successfully synthesized. These nanocrystals exhibit outstanding hydrogen generation capability (1160 µmol g-1 h-1 in pure water) and demonstrate remarkable performance in organic dye degradation using ultrasonication. The crystal structure of this newly discovered BaTi2O5 phase, is determined by a combination of synchrotron Powder Diffraction refinement and X-ray adsorption techniques, including X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS). Density Functional Theory calculations revealed that the newly-discovered BaTi2O5 phase demonstrates dipole moments along the z-axis, distributed in an antiparallel direction within a single unit cell. These inherent dipoles induce a surface polarization and a ferroelectric-flexoelectric response under mechanical stimuli when the materials go to nano dimension. With a band alignment well-suitable for hydrogen and reactive oxygen species generation, this BaTi2O5 phase demonstrates promising potential for Mechanocatalysis. The discovery of this distinct phase not only enriches the material candidates for mechanocatalysis but also provides valuable insights.

Flexoelectricity Modulated Electron Transport of 2D Indium Oxide

The phenomenon of flexoelectricity, wherein mechanical deformation induces alterations in the electron configuration of metal oxides, has emerged as a promising avenue for regulating electron transport. Leveraging this mechanism, stress sensing can be optimized through precise modulation of electron transport. In this study, the electron transport in 2D ultra-smooth In2O3 crystals is modulated via flexoelectricity. By subjecting cubic In2O3 (c-In2O3) crystals to significant strain gradients using an atomic force microscope (AFM) tip, the crystal symmetry is broken, resulting in the separation of positive and negative charge centers. Upon applying nano-scale stress up to 100 nN, the output voltage and power values reach their maximum, e.g. 2.2 mV and 0.2 pW, respectively. The flexoelectric coefficient and flexocoupling coefficient of c-In2O3 are determined as ≈0.49 nC m-1 and 0.4 V, respectively. More importantly, the sensitivity of the nano-stress sensor upon c-In2O3 flexoelectric effect reaches 20 nN, which is four to six orders smaller than that fabricated with other low dimensional materials based on the piezoresistive, capacitive, and piezoelectric effect. Such a deformation-induced polarization modulates the band structure of c-In2O3, significantly reducing the Schottky barrier height (SBH), thereby regulating its electron transport. This finding highlights the potential of flexoelectricity in enabling high-performance nano-stress sensing through precise control of electron transport.

Piezo-Flexocatalysis of Single-Atom Pt-Loaded Graphitic Carbon Nitride

This study develops a single-atom Pt-loaded graphitic carbon nitride (SA-Pt/CN) and evaluates its piezo-flexocatalytic properties by conducting a hydrogen evolution reaction (HER) and Rhodamine B (RB) dye degradation test under ultrasonic vibration in the dark. SA-Pt/CN has a hydrogen gas yield of 1283.8 µmol g-1 h-1, which is 23.3 times higher than that of pristine g-C3N4. Moreover, SA-Pt/CN enhances the dye degradation reaction rate by ≈2.3 times compared with the pristine sample. SA-Pt/CN exhibits lattice distortion and strain gradient enlargement caused by the single atom Pt at the N sites of g-C3N4, which disrupts the symmetric structure and contributes to the enhancement of piezoelectric and flexoelectric polarization. As far as it is known, this is the first study to investigate the piezo-flexocatalytic reaction of SA-Pt/CN without light irradiation and provides new insights into single-atom piezocatalysts.

MoS2@MWCNTs with Rich Vacancy Defects for Effective Piezocatalytic Degradation of Norfloxacin via Innergenerated-H2O2: Enhanced Nonradical Pathway and Synergistic Mechanism with Radical Pathway

Molybdenum disulfide (MoS2)-based materials for piezocatalysis are unsatisfactory due to their low actual piezoelectric coefficient and poor electrical conductivity. Herein, 1T/3R phase MoS2 grown in situ on multiwalled carbon nanotubes (MWCNTs) was proposed. MoS2@MWCNTs exhibited the interwoven morphology of thin nanoflowers and tubes, and the piezoelectric response of MoS2@MWCNTs was 4.07 times higher than that of MoS2 via piezoresponse force microscopy (PFM) characterization. MoS2@MWCNTs exhibited superior activity with a 91% degradation rate of norfloxacin (NOR) after actually working 24 min (as for rhodamine B, reached 100% within 18 min) by pulse-mode ultrasonic vibration-triggered piezocatalysis. It was found that piezocatalysis for removing pollutants was attributed to the synergistic effect of free radicals (•OH and O2•-) and nonfree radical (1O2, key role) pathways, together with the innergenerated-H2O2 promoting the degradation rate. 1O2 can be generated by electron transfer and energy transfer pathways. The presence of oxygen vacancies (OVs) induced the transformation of O2 to 1O2 by triplet energy transfer. The fast charge transfer in MoS2@MWCNTs heterostructure and the coexistence of sulfur vacancies and OVs enhanced charge carrier separation resulting in a prominent piezoelectric effect. This work opens up new avenues for the development of efficient piezocatalysts that can be utilized for environmental purification.

Boosting Efficiency in Piezo-Photocatalysis Process Using Poled Ba0.7Sr0.3TiO3 Nanorod Arrays for Pollutant Degradation and Hydrogen Production

Recently, the combination of the piezoelectric effect in the photocatalytic process, referred to as piezo-photocatalysis, has gained considerable attention as a promising approach for enhancing the degradation of organic pollutants. In this investigation, we studied the piezo-photocatalysis by fabricating arrays of barium strontium titanate (Ba0.7Sr0.3TiO3) nanorods (BST NRs) on a glass substrate as recoverable catalysts. We found that the degradation rate constant k of the rhodamine B solution achieved 0.0447 min-1 using poled BST NRs in the piezo-photocatalytic process, indicating a 2-fold increase in efficiency compared to the photocatalytic process (0.00183 min-1) utilizing the same material. This is mainly ascribed to the generation of the piezopotential in the poled BST NRs under ultrasonic vibration. Moreover, the BST NR array demonstrated a hydrogen (H2) production rate of 411.5 μmol g-1 h-1. In the photoelectrochemical process, the photocurrent density of poled BST NRs achieved 1.97 mA cm-2 at an applied potential of 1.23 V (ERHE (reversible hydrogen electrode)) under ultrasonic vibrations, representing a 1.7-fold increase compared with the poled BST NRs without ultrasonic vibrations. The measurement results from the liquid chromatograph mass spectrometer (LC-MS) demonstrated the formulation of a degradation pathway for rhodamine B molecules. Moreover, ab initio molecular dynamics (AIMD) simulation results demonstrate the dominance of hydroxyl radicals (•OH) rather than superoxide radicals (•O2-) in the degradation process. This study not only benefits the understanding of the principle of the piezo-photocatalytic process but also provides a new perspective for improving the catalytic efficiency for organic pollutants degradation.

Flexocatalytic Reduction of Tumor Interstitial Fluid/Solid Pressure for Efficient Nanodrug Penetration

The practical efficacy of nanomedicines for treating solid tumors is frequently low, predominantly due to the elevated interstitial pressure within such tumors that obstructs the penetration of nanomedicines. This increased interstitial pressure originates from both liquid and solid stresses related to an undeveloped vascular network and excessive fibroblast proliferation. To specifically resolve the penetration issues of nanomedicines for tumor treatment, this study introduces a holistic "dual-faceted" approach. A treatment platform predicated on the WS2/Pt Schottky heterojunction was adopted, and flexocatalysis technology was used to disintegrate tumor interstitial fluids, thus producing oxygen and reactive oxygen species and effectively mitigating the interstitial fluid pressure. The chemotherapeutic agent curcumin was incorporated to further suppress the activity of cancer-associated fibroblasts, minimize collagen deposition in the extracellular matrix, and alleviate solid stress. Nanomedicines achieve homologous targeting by enveloping the tumor cell membrane. It was found that this multidimensional strategy not only alleviated the high-pressure milieu of the tumor interstitium─which enhanced the efficiency of nanomedicine delivery─but also triggered tumor cell apoptosis via the generated reactive oxygen species and modulated the tumor microenvironment. This, in turn, amplified immune responses, substantially optimizing the therapeutic impacts of nanomedicines.

Significant hydrogen generation via photo-mechanical coupling in flexible methylammonium lead iodide nanowires

The flexoelectric effect, which refers to the mechanical-electric coupling between strain gradient and charge polarization, should be considered for use in charge production for catalytically driving chemical reactions. We have previously revealed that halide perovskites can generate orders of higher magnitude flexoelectricity under the illumination of light than in the dark. In this study, we report the catalytic hydrogen production by photo-mechanical coupling involving the photoflexoelectric effect of flexible methylammonium lead iodide (MAPbI3) nanowires (NWs) in hydrogen iodide solution. Upon concurrent light illumination and mechanical vibration, large strain gradients were introduced in flexible MAPbI3 NWs, which subsequently induced significant hydrogen generation (at a rate of 756.5 μmol g-1 h-1, surpassing those values from either photo- or piezocatalysis of MAPbI3 nanoparticles). This photo-mechanical coupling strategy of mechanocatalysis, which enables the simultaneous utilization of multiple energy sources, provides a potentially new mechanism in mechanochemistry for highly efficient hydrogen production.

Flexo-/Piezoelectric Polarization Boosting Exciton Dissociation in Curved Two-Dimensional Carbon Nitride Photocatalyst

Two-dimensional (2D) carbon nitride (CN) materials have received tremendous attention as photocatalysts for clean energy and environmental treatment. However, the photocatalytic efficiency of CN is constrained by the high exciton binding energy and sluggish charge kinetics due to weak dielectric screening, impeding the overall process. Herein, localized flexo-/piezoelectric polarization is introduced via strain engineering, boosting exciton dissociation and promoting charge separation to enhance the multielectron photocatalytic process. Consequently, the exciton binding energy of polarized CN is reduced from 52 to 34 meV, and the hydrogen evolution yield increased by 2.9 times compared to that of the pristine CN. For other photocatalytic reactions (e.g., H2O2 production), the polarized CN also maintained a 2.1-fold increase compared to the pristine CN. This strategy of inducing localized polarization via strain engineering provides new insights for boosting photocatalytic reactions involving electrons.

Mechanoredox/Nickel Co-Catalyzed Cross Electrophile Coupling of Benzotriazinones with Alkyl (Pseudo)halides

An air-tolerant mechanoredox/nickel cocatalyzed cross electrophile coupling of benzotriazinones with alkyl (pseudo)halides is developed by liquid-assisting grinding in the presence of manganese powders and strontium titanate as a reductant and a cocatalyst, respectively. Mechanical activation of metal surfaces via ball milling eliminates the chemical activator for manganese, while mechanoredox cocatalysis of strontium titanate remarkably improves the aryl/alkyl cross electrophile coupling via piezoelectricity-mediated radical generation from alkyl halides. Both benzotriazinones and alkyl (pseudo)halides display reactivities in the mechanoredox/nickel cocatalysis different from those of conventional thermal chemistry in solution. The scope of the reaction is demonstrated with 26 examples, showing a high chemoselectivity of bromides vs chlorides.

Ultra-fast Piezocatalysts Enabled By Interfacial Interaction of Reduced Graphene Oxide/MoS2 Heterostructures

The catalytic activity has been investigated in 2D materials, and the unique structural and electronic properties contribute to their success in conventional heterogeneous catalysis. Heterojunction-based piezocatalysis has attracted increasing attention due to the band-structure engineering and the enhanced charge carrier separation by prominent piezoelectric effect. However, the piezocatalytic behavior of van der Waals (vdW) heterostructures is still unknown, and the finite active sites, catalyst poisoning, and poor conductivity are challenges for developing good piezocatalysts. Herein, a reduced graphene oxide (rGO)-MoS₂ heterostructure is rationally designed to tackle these challenges. The heterostructure shows a record-high piezocatalytic degradation rate of 1.40 × 10² L mol^-1 s^-1 , which is 7.86 times higher than MoS₂ nanosheets. Piezoresponse force microscope measurements and density functional theory calculation reveal that the coupling between semiconductive and piezoelectric properties in the vdW heterojunction is vital to break the metallic state screening effect at the MoS₂ edge for keeping the piezoelectric potential. The dynamic charges generated by MoS₂ and the fast charge transfer in rGO activate and maintain catalytically active sites for pollutant degradation with an ultra-fast rate and good stability. The working mechanism opens new avenues for developing efficient catalysts significant to wastewater treatments and other applications.