Piezoelectric Field Research Articles

Construction of Dual Electric Field Synergistic and Magnetic Recyclable SnFe2O4/ZnO Photocatalyst.

The recombination of photoinduced carriers hampers the photocatalysis process. Construction of the heterojunction and built-in piezoelectric field boosts the separation of electrons and holes. Herein, a novel magnetic recyclable SnFe2O4(SFO)/ZnO composite with enhanced photocatalytic performance based on the dual electric field synergism was proposed for the first time. This composite apparently alleviates the carrier recombination in SFO and extends the absorption spectrum of ZnO to the full spectrum. Consequently, 20%SFO/ZnO exhibits an excellent efficiency, which is 2.45 times that of ZnO and 4.61 times that of SFO, respectively. The differences in size and morphology between the SFO nanoparticles and the ZnO nanorods provide more contact areas, thus enlarging the deformation and enhancing the piezoelectric effect. The heterojunction and the piezoelectric field work together to modulate the transferring of carriers and elevate the photocatalytic activity. This design offers a plausible avenue for preparing efficient recyclable photocatalysts for application.

Multilayer structured bismuth silicate inverse opal film with improved piezo-photocatalytic performance for wastewater purification and dyes removal

Suppressing the recombination of photogenerated charge carriers is thought to be possible by combining the photocatalytic method with the piezoelectric action of piezoelectric semiconductors. A new piezo-photocatalyst, Bi2SiO5 inverse opal film, was prepared by inverse template method. The introduction of 3D ordered inverse opal structure was favorable for light harvesting. The unique two-dimensional layered structure of Bi2SiO5 facilitates electron-hole (e--h+) pair separation. The degradation efficiency of Bi2SiO5 inverse opal film is 15 times higher than that of planar- Bi2SiO5 film under UV light alone. When co-excited by UV light and mechanical energy (ultrasonic vibration), the Bi2SiO5 inverse opal film demonstrated a significantly accelerated degradation rate of RhB compared with planar Bi2SiO5 film. The enhanced piezo-photocatalytic efficiency resulted from the effective separation of photogenerated electron-hole pairs in the Bi2SiO5 inverse opal under the inherent piezoelectric field. Consequently, our work offers fresh perspective on piezo-photocatalytic materials based on Bi2SiO5 for effective wastewater treatment.

Defect Dipole Asymmetry Response Induces Electrobending Deformation in Thin Piezoceramics.

Ultrahigh electrostrains (>1%) in several piezoceramic systems have been reported since 2022, which attracts more and more interest in the field of piezoelectricity; however, the mechanism is still unclear. Here, in nonstoichiometric (K_{0.48}Na_{0.52})_{0.99}NbO_{2.995} ceramics, we have directly observed a novel electric field-induced bending (electrobending) phenomenon that visually exhibits an alternating concave-convex deformation under an electric field of ±50 kV cm^{-1}, leading to the measured ultrahigh electrostrain. It is demonstrated that the electrobending deformation arises from the different stresses due to the stretching or compression of the oriented-defect dipoles in the upper and lower surface layers of the ceramics under an electric field. Consequently, a giant apparent electrostrain of 31.8% is obtained at room temperature. Our discovery is an important addition and refinement to the field of condensed matter physics, while also providing a new strategy and shedding light on the design of future high-performance actuators and intelligent devices.

Giant piezoelectricity in antiferromagnetic CrS2 and CrSe2 monolayers

Abstract Two-dimensional (2D) materials, particularly transition metal dichalcogenides (TMDs), have garnered significant attention in the nanoscale piezoelectric field due to their high crystallinity and ability to withstand large strains. Through density-functional theory calculations, we have discovered that monolayer H-phase CrS2 and CrSe2 exhibit antiferromagnetic semiconducting properties, in contrast to the previously held belief that they were nonmagnetic (NM) semiconductors. While the piezoelectric coefficients of NM CrS2 and CrSe2 are comparable to those of MoS2, their antiferromagnetic ground states demonstrate significantly enhanced piezoelectric coefficients ( d 11 ) of 27.66 pm V−1 and 52.36 pm V−1, respectively. These values exceed that of MoS2 by an order of magnitude, marking the highest recorded for TMD materials and the highest in 2D magnetic materials to date. The greatly enhanced piezoelectric responses in the antiferromagnetic states of CrS2 and CrSe2 compared to their NM states arise from three primary factors. Firstly, the displacement of the Wannier center under strain is more pronounced in the antiferromagnetic state, leading to a greater change in dipole moment (enhanced clamped-ion contribution). Secondly, there is a heightened polarization change due to internal atomic distortions (internal-strain term) in response to macroscopic strain in the antiferromagnetic state. Thirdly, the material undergoes a softening of the elastic coefficient in its antiferromagnetic state. These findings open new avenues for designing high-performance piezoelectric and magnetic multifunctional materials.

Realization of excellent piezoelectricity and high Curie temperature in BF–BT ceramics via structural regulation and domain engineering

BiFeO3–BaTiO3 (BF–BT) is one of the lead-free piezoceramic materials with high Curie temperature (TC) and high polarization. Herein, the (Bi0.5Li0.5Ti)6+ group elements are introduced into the 0.75BiFeO3−0.25BaTiO3 (0.75BF–0.25BT) system to optimize comprehensive performances via optimizing the intrinsic piezoelectric contribution and the extrinsic piezoelectric contribution. For intrinsic piezoelectric contribution, the tetragonal phase ratio of the ceramics is increased. For extrinsic piezoelectric contribution, the grain structures and the domain structures of the ceramics are improved with a relaxor state in which small-sized domains and large-sized domains coexist. The best overall performances are obtained at x = 0.010 with piezoelectric constant d33 ∼ 130 pC/N at room temperature, d33 ∼ 231 pC/N at 313 °C, resistance ρ ∼ 1.49 × 106 Ω cm at 300 °C, and Curie temperature TC ∼ 632 °C that improved significantly. Moreover, when x = 0.010, the piezoelectric thermal stability is also significantly improved, with Δd33 being less than 15% before 200 °C and maintaining 60% of d33 at 400 °C. The present experiments provide a new strategy to investigate the origin of the enhanced piezoelectric response of BF–BT ceramics as well as their applications in the field of high-temperature lead-free piezoelectricity.

Piezoelectric photocatalytic degradation of formaldehyde based on BFO@OCN heterojunctions

Piezoelectric photocatalysts represent a new class of environment-cleaning materials containing a self-electricity nanogenerator. Wind is one of the common energy sources in the natural environment. The piezoelectric field generated by the action of wind on piezoelectric materials can promote the adsorption of organic pollutants and also facilitate the transfer and separation of photogenerated carriers, thereby improving the efficiency of photocatalytic degradation of formaldehyde. This work developed a BFO@OCN heterojunction composite combing BiFeO3 nanocubes (BFO) and g-C3N4 nanosheets with oxygen vacancies (OCN). This piezoelectric photocatalyst exhibited high activity in degradation of formaldehyde in gas under light irradiation. Within 90 min, the formaldehyde concentration reduced from 1.50 ppm to 0.68 ppm, almost 2 times higher than the pure CN. This enhanced catalytic performance can be attributed to the synergistic interplay between the wind-induced piezoelectric field generated by BFO nanocubes in wind and the heterojunction with oxygen vacancies from g-C3N4 nanosheets. The piezoelectric field promoted the transfer of photoelectrons and holes in opposite directions, which could inhibit their recombination. Meanwhile, it also induced the generation of oxygen vacancies from g-C3N4 nanosheets. Our research findings provided a feasible strategy for developing high-efficiency piezoelectric photocatalysts, which could be decorated on the car outer-surface for self-cleaning and air purification under sunlight irradiation.

Tellurenated Compounds: Synthesis and Application in Ion Detection and as a Catalyst

AbstractTellurium is now recognized as a ‘technology-critical element’ that is quickly being used in innovative applications. The chemistry of organotellurium ligands has improved rapidly during the last three decades. Because of their enhanced accessibility and the possibility that they would display significantly different properties than their sulfur counterparts, these ligands of heavier chalcogens have sparked considerable attention. The next sections will go through the various tellurium ligands and associated transition-metal complexes. Organochalcogen ligands are exceedingly flexible ligands that may react with nearly any transition metal to form a wide range of compounds, including multidentate ligands.Tellurides of various metals have lately been investigated for potential use in storage devices, solar cells, piezoelectric, medical applications, electronics, photothermal treatment, nanoplatelets, nanocrystals, catalysis, and other fields. Researchers are interested in metal chalcogenide heterostructures because of their improved charge transport and synergistic optoelectronic and catalytic properties. A sensor for various metals based on Te electrodes and a donor ligand are used to generate electrical signals and identify different metals. Due to the scarcity of tellurium, metal telluride nanocrystal heterostructures have received less attention than metal sulfide and metal selenide nanocrystal heterostructures.1 Introduction2 Tellurenated Compounds of Zwitterionic Nature3 Synthesis of Tellurenated Ligands and Complexes4 Catalytic Application and and Suzuki–Miyara Coupling5 Tellurenated Sensors for Metal-Ion Sensing5.1 Tellurium-Ion Detectors5.2 Drawbacks/Catalyst Poisoning5.3 Disadvantages5.4 Advantages and Future Prospects6 Conclusions

Enhanced Ferroelectric Polarization in Au@BaTiO3 Yolk-in-Shell Nanostructure for Synergistic Boosting Visible-Light- Piezocatalytic CO2 Reduction.

Developing efficient photo-piezocatalytic systems to achieve the conversion of renewable energy to chemical energy emerges enormous potential. However, poor catalytic efficiency remains a significant obstacle to future practical applications. Herein, a series of unique Au@BaTiO3 (Au@BT) yolk-shell nanostructure photo-piezocatalyst is constructed with single Au nanoparticle (Au NP) embedded in different positions within ferroelectric BaTiO3 hollow nanosphere (BT-HNS). This special structure showcases excellent mechanical force sensitivity and provides ample plasmon-induced interfacial charge-transfer pathways. In addition, the powerful piezoelectric polarization electric field induced by the enhanced ferroelectric polarization electric field via corona poling treatment in BT-HNS further promotes charge separation, CO2 adsorption and key intermediate conversion. Notably, BT with single Au NP encapsulated into hollow nanosphere shell with reinforced polarization (Au@BT-1-P) shows synergistically improved photo-piezocatalytic CO2 reduction activity for producing CO with a high production rate of 31.29 µmol g-1 h-1 under visible light irradiation and ultrasonic vibration. This work highlights a generic tactic for optimized design of high-performance and multifunctional nanostructured photo-piezocatalyst. Meanwhile, these yolk-in-shell nanostructures with single Au nanoparticle as an ideal model may hold great promise to inspire in-depth exploration of carrier dynamics and mechanistic understanding of the catalytic reaction.

Eliminating interface shielding effect endowed by piezoelectric polarization in S-scheme heterojunction for high-efficiency H2 evolution

Eliminating the interface shielding effect within step-scheme (S-scheme) heterojunctions which can attenuate the separation driving force of built-in electric field plays a vital role in enhancing the photocatalytic performance. Herein, an extra driving force induced by piezoelectric field is introduced to mitigate such predicament in S-scheme, thereby facilitating the charge separation. Specifically, the piezoelectric CuInS2-BiFeO3 S-scheme heterojunction which with powerful piezoelectric field endowed by the piezoelectric BiFeO3 is constructed via a facile electrostatic self-assembly strategy and served as the touchstone to verify that hypothesis. The direction of built-in field between the heterojunction interface that is orienting from CuInS2 to BiFeO3 has been confirmed by in-situ X-ray photoelectron spectroscopy and electron paramagnetic resonance. Furthermore, the obviously piezo-field at the interface of CuInS2-BiFeO3 which can tilt energy band to enhance the built-in field under external force is also revealed by piezoresponse force microscopy. Consequently, benefiting from the highly-efficient charge separation offered by the synergy of piezoelectric field and S-scheme built-in electric field, a remarkably H2 production rate of 1465.1 µmol/g is achieved under simultaneous visible light and ultrasonic vibration irradiation. This work sheds light on the role of external field in enhancing the efficient separation of carriers in S-scheme heterojunctions.

Piezoelectric field accelerating charge transfer in Z-scheme heterojunction 2D-KNbO3/1D-CdS for efficient piezo-photocatalytic H2 evolution and TCH degradation

The piezo-phototronic effect utilizes the piezoelectric polarization field to tune the photogenerated carrier separation and transport performance in heterojunctions, which portrays a promising strategy for addressing energy shortage and environmental pollutants. Herein, a novel Z-scheme piezoelectric semiconductor heterojunction, 2D-KNbO3/1D-CdS-x (KNCS-x), was fabricated using hydrothermal and solvothermal methods, resulting in enhanced redox capacity. Under the simultaneous light and strain, KNCS-15 exhibits the highest piezo-photocatalytic activity, with degradation rates of tetracycline hydrochloride degradation rate constant, H2O2 as well as H2 production rates being 1.806 × 10−2s−1, 45.56 mM·h−1·g−1 and 8.87 mmol·h−1·g−1, respectively, which are 1.4, 2.4 and 1.9 times of photocatalysis alone, and 9.8, 9.2 and 9.8 times of piezocatalysis alone. DFT calculations, EPR and PALS indicate that the Z-scheme structure realizes effective separation of electron-hole pairs with strong redox ability and a higher carrier concentration. The enhanced catalytic activity is attributed to the introduction of piezoelectric potential, which facilitates improved spatial separation of electrons with high reduction and holes with high oxidation potential.

Piezoelectric Energy Harvesting for Civil Engineering Applications

This work embarks on an exploration of piezoelectric energy harvesting (PEH), seeking to unravel its potential and practicality. PEH has emerged as a promising technology in the field of civil engineering, offering a sustainable approach to generating energy from ambient mechanical vibrations. We will explore the applications and advancements of PEH within the realm of civil engineering, focusing on publications, especially from the years 2020 to 2024. The purpose of this study is to thoroughly examine the potential and practicality of PEH in civil engineering applications. It delves into the fundamental principles of energy conversion and explores its use in various areas, such as roadways, railways, bridges, buildings, ocean wave-based energy harvesting, structural health monitoring, and even extraterrestrial settings. Despite the potential benefits of PEH in these domains, there are significant challenges that need to be addressed. These challenges include inefficient energy conversion, limitations in scalability, concerns regarding durability, and issues with integration. This review article aims to address these existing challenges and the research gap in the piezoelectric field.

Vacancy defect and piezoelectric field assisted photocatalytic performance of BiO(Cl1/3Br1/3I1/3)x for the degradation of organic pollutants

Semiconductor photocatalysts have been widely researched in wastewater treatment of organic dyes, among which bismuth halide semiconductors have shown great application prospects due to their unique layered structure and diverse micromorphology. As for photocatalysis, high concentration of photo-generated carriers and their effective separation are considered to be the key to obtain excellent photocatalytic performance. In view of the common issues of high bandgap energy and low carrier separation rate in bismuth halide, in this paper, the BiO(Cl1/3Br1/3I1/3)x catalysts with different proportions of Bi3+ and (Cl1/3Br1/3I1/3)- were designed and synthesized by hydrothermal method, through constructing hybrid energy levels and thus accomplishing by multi-halogen doping to widen the light absorption range. For another, the efficient separation of electrons and holes was achieved in BiO(Cl1/3Br1/3I1/3)x in virtue of a built-in field stemmed from the intrinsic piezoelectric effect, and band tilting. Meanwhile, more active sites were induced by Vo•• and VBiʹʹʹ due to the directional impact of the built-in field. Ultimately, BiO(Cl1/3Br1/3I1/3)5/7 demonstrated the optimum catalytic performance under the combined light irradiation and ultrasonic vibration, with the degradation efficiency of MB reaching 91.28% in 60 min and the k of 0.0360 min-1, and 97.44% degradation efficiency of Rh B within 18 min and the k of 0.1565 min-1 together with excellent cycling stability. The prepared BiO(Cl1/3Br1/3I1/3)5/7 catalyst has a huge application potential for the degradation of wastewater, taking full advantage of environmental vibration energy and light energy.

Internal quantum efficiency improvement of InGaN-based red LED by using double V-pits layers as strain relief layer

Micro/mini light emitting diodes (LEDs) based on AlInGaN material system have vast potential in display applications. Nevertheless, the low internal quantum efficiency (IQE) of InGaN-based red LED limits its development and application. In the epitaxial structure of our designed red LED, double V-pits layers were used as strain relief layers to reduce compressive strain and improve the IQE of the active layer. First, InGaN/GaN superlattices (SLs) were grown below the active layer to form low-density large V-pits layer. Subsequently, multi-period green and red composite quantum wells were adopted as the active layer. A high-density small V-pits layer was introduced into the active region to release the compressive strain by adjusting the growth parameters of green multiple quantum wells (MQWs). The V-shaped pits divide the continuous large-area of active layer into mutually isolated small pieces, which prevents the transmission of strain and converts the long-range strain into separated local strain. The peak IQEs of LED A2 with single V-pits layer and LED B4 with double V-pits layers were measured to be 10.5% at 613 nm and 21.5% at 612.1 nm, respectively. The IQE is greatly improved by 204.7%. The research results indicate that the double V-pits layers structure can alleviate the compressive strain of InGaN QWs more effectively, reduce the influence of piezoelectric polarization field, and improve the IQE.

Photo-induced BiVO4 to produce P25-like structure for enhancing piezo-photocatalytic activity

Piezo-photocatalysis is considered a promising pollutant treatment strategy. Herein, a simple strategy is proposed to construct lattice distortion in BiVO4 to realize an efficient piezo-photocatalytic degradation process. Specifically, the phase structure of BiVO4 is regulated by introducing different wavelengths of illumination, resulting in the homojunction formation. Compared with BiVO4 prepared under dark conditions (BVO), the VO bonds are shortened and the BiO bonds are elongated in the structure of BiVO4 synthesized under 460 nm illumination (BVO-460). Furthermore, the Tafel curve reveals that electrons flow from the monoclinic phase to the tetragonal phase. By the tetracycline hydrochloride degradation, it is found that the BVO-460 has excellent piezo-photocatalytic efficiency, attributed to the piezoelectric polarization field enhanced charge transfer. In this paper, the piezo-photocatalytic performance of BiVO4 is investigated in the insight of crystal phase structure, which provided a new idea for the application of layered bismuth-based materials in environmental purification.

Two-Level regulation photocatalytic activity of Bi2WO6/COFs with ligand engineering and piezoelectric field for Highly-Efficient degradation of antibiotics

Covalent organic frameworks (COFs) have attracted significant attention in photocatalytic water purification due to their structural designability and sufficiently negative conduction band edges. However, the limited oxidation capacity of single COFs and the low utilization rate of photogenerated carriers result in suboptimal catalytic activity. To address these challenges, we propose a two-level regulation strategy that involves ligand engineering and the introduction of a piezoelectric field to enhance the photocatalytic performance of COF-based photocatalysts. In this study, we combined the piezoelectric material Bi2WO6 with COFs modified with different ligands to design a series of Bi2WO6/R-COFs (R=H, F, CH3O) heterojunctions. Modifying COFs with –OCH3 functional group tuned the local electron distribution, thereby remarkably improving photogenerated electrons transfer rate constant. Besides, the incorporation of Bi2WO6 generated a piezoelectric field under ultrasound, which provides a strong driving force for photocatalytic. Meanwhile, the construction of the heterojunctions offered multi-channel for the generation of reactive oxygen species. As a result, the photocatalytic degradation rate of Bi2WO6/CH3O-COFs reached 93.5 % toward sulfamethoxazole within 48 min under ultrasound-coupled light irradiation, which is nearly three times higher than Bi2WO6/H-COFs. Furthermore, Bi2WO6/CH3O-COFs demonstrated superior degradation performance for other pollutants, including p-chlorophenol, bisphenol A, tetracycline, and phenol, with degradation efficiencies of 99.0 %, 98.4 %, 93.5 % and 88.1 %, respectively. This work proposes a two-level modulation strategy that significantly enhances the antibiotic degradation performance of COF-based catalysts, offering a new perspective for the design of photocatalysts for environmental remediation.

Construction of a Bi2S3/Bi0.5Na0.5TiO3 Composite Catalyst with S Vacancies for Efficient Piezo-Photocatalytic Hydrogen Production.

Photocatalytic hydrogen production with low environmental and economic costs is expected to be a powerful means to alleviate energy and environmental problems. However, how to inhibit the rapid recombination of photogenerated carriers is a challenge that photocatalytic hydrogen production has to face. In this study, the coupling of the piezoelectric effect and vacancy engineering into the photocatalytic reaction process synergistically promoted carrier separation, thereby promoting the improvement of hydrogen production performance. Specifically, the novel dual piezoelectric Bi2S3/Bi0.5Na0.5TiO3 (BS-12/BNT) piezo-photocatalyst rich in S vacancies was synthesized by an impregnation method. The hydrogen generation rate of 5% BS-12/BNT under the combined impact of light and ultrasound was up to 1019.39 μmol/g/h, which is 9.5 times higher than that of pure BNT. Various characterization analyses have confirmed that the piezoelectric-photocatalytic activity of BS/BNT composite materials is significantly improved, mainly due to the introduction of S vacancies and piezoelectric fields, which enhance the absorption of sunlight, reduce interface resistance, and so raise the photogenerated carriers' separation efficiency. In addition, the stability of BS/BNT is significantly better than that of the previously synthesized catalysts. Finally, according to the results of XPS, UV-vis, and ESR, the active groups and possible electron transfer paths generated during the piezoelectric-photocatalytic hydrogen production process were studied. This work presents a new approach to promote hydrogen production performance through the synergistic effect of the piezoelectric effect and S vacancies.

Recent Advances in Piezoelectric Coupled with Photocatalytic Reaction System: Synergistic Mechanism, Enhancement Factors, and Application.

The field of photocatalysis has demonstrated numerous advantages in the domains of environmental protection, energy, and materials science. However, conventional modification methods fail to simultaneously enhance carrier separation efficiency, redox capacity, and visible light absorption solely through light activation due to the intrinsic band structure limitations of photocatalysts. In addition to modification methods, the introduction of an external field, such as a piezoelectric field, can effectively address deficiencies in each step of the photocatalytic process and enhance the overall performance. The assistance of a piezoelectric field overcomes the limitations inherent in traditional photocatalytic systems. Hence, this review provides a comprehensive overview of recent advancements in piezoelectric-assisted photocatalysis and thoroughly investigates the interaction between the alternating piezoelectric field and photocatalytic processes. Various ideas for synergistic enhancement of the piezoelectric and photocatalytic properties are also explored. This multifield catalytic system shows remarkable performance in stability, pollutant degradation, and energy conversion, distinguishing it from single catalytic systems. Finally, an in-depth analysis is conducted to address the challenges and prospects associated with piezoelectric photocatalysis technology.

Enhanced visible light responsive piezoelectric photocatalysis based on Bi2S3 coated BaTiO3 nanorods heterostructures

Although the presence of the built-in electric field will solve the problem of carrier complexation in photocatalytic systems to some extent. However, free carriers will quickly shield the stabilized electric field and lose its effect. Therefore, how to introduce the dynamic piezoelectric field into the photocatalytic system has become an imminent problem. Herein, we developed an overcoated, visible light responsive, piezoelectric-assisted photocatalytic system by depositing Bi2S3 photocatalysts with a narrow-band system onto the surface of highly piezo-responsive BaTiO3 nanorods (BTO NRs). The heterojunction structure, bound by Bi-O chemical bonding, enhances carrier transport efficiency under the influence of the piezoelectric field. In the degradation experiments, the first-order rate constant for the degradation of chlortetracycline hydrochloride (CTC) in the BTO NRs/Bi2S3 system with the optimal complex ratio was 0.0276 min−1, which was 3.1 and 7.8 times higher than that of BTO NRs and Bi2S3, respectively. Additionally, we deduced the degradation pathways of CTC through a combination of Density functional theory (DFT) calculations and Liquid Chromatograph Mass Spectrometer (LC-MS), evaluating the toxicity of the intermediates. This complex system, featuring a highly photo-responsive semiconductor as a photo-acceptor deposited on a piezoelectric semiconductor surface providing a dynamic built-in electric field, enhances carrier separation efficiency under optimal light energy utilization conditions. These findings present novel and effective strategies for addressing two primary challenges in photocatalytic systems: low spectral utilization and significant photogenerated carrier complexation.

S-type Bi2S3/BiOBr heterojunction with robust piezo-photocatalytic dye removal activity: Degradation performance and mechanism investigation

In this work, an efficient S-type Bi2S3/BiOBr piezo-photocatalysts was prepared by the decoration of Bi2S3 nanorods on the surface of BiOBr nanosheets. The piezo/photo/piezo-photocatalytic performance of samples were evaluated under the irradiation of ultrasonic and/or simulated-sunlight employing methyl orange (MO) as a target reactant, indicating that above catalytic activity of BiOBr is able to be elevated after Bi2S3 attachment. Particularly, the 10%Bi2S3/BiOBr sample exhibits the optimal catalytic performance. It is worth noting that the 10%Bi2S3/BiOBr sample achieves much higher piezo-photocatalytic MO removal efficiency than its photocatalysis and piezocatalysis, demonstrating a remarkable synergistic improvement between piezocatalysis and photocatalysis with a synergistic enhancement factor (SF) of ∼1.29. The formation of S-type heterojunction in the Bi2S3/BiOBr composite was directly confirmed by the combination of density functional theory (DFT) calculation and in-situ irradiated X-ray photoelectron spectroscopy (ISI-XPS) measurement, elevating the surface separation of generated charges. Meanwhile, the ultrasonic-excited piezoelectric polarization field in BiOBr nanosheets excited by ultrasonic irradiation promotes the bulk segregate of generated charges. Benefiting from above two aspect effects, the overall separation of generated charges can be effectively achieved, leading to outstanding piezo-photocatalytic degradation activity of Bi2S3/BiOBr composite.

Recent Advances in Flexible Self-Powered Sensors in Piezoelectric, Triboelectric, and Pyroelectric Fields

The rise of the Internet of things has catalyzed extensive research in the realm of flexible wearable sensors. In comparison with conventional sensor power supply methods that are reliant on external sources, self-powered sensors offer notable advantages in wearable comfort, device structure, and functional expansion. The energy-harvesting modes dominated by piezoelectric nanogenerators (PENGs), triboelectric nanogenerators (TENGs), and pyroelectric nanogenerators (PyENGs) create more possibilities for flexible self-powered sensors. This paper meticulously examines the progress in flexible self-powered devices harnessing TENG, PENG, and PyENG technologies and highlights the evolution of these sensors concerning the material selection, pioneering manufacturing techniques, and device architecture. It also focuses on the research progress of sensors with composite power generation modes. By amalgamating pivotal discoveries and emerging trends, this review not only furnishes a comprehensive portrayal of the present landscape but also accentuates avenues for future research and the application of flexible self-powered sensor technology.