Directing Charge Transfer in a Chemical-Bonded BaTiO3 @ReS2 Schottky Heterojunction for Piezoelectric Enhanced Photocatalysis

Noninvasive Vagus Nerve Electrical Stimulation for Immune Modulation in Sepsis Therapy

Sepsis presents a significant medical challenge due to its intense inflammatory response to infection, often resulting in high mortality rates. A promising therapeutic strategy targets the cholinergic anti-inflammatory pathway (CAIP), which regulates immune responses. This study investigates the ingestion of piezoelectric particles that adhere to the stomach lining, specifically targeting TRPV1 receptors. In a mouse model of sepsis, these particles, when activated by low-intensity pulsed ultrasound, generate mild electrical pulses. These pulses stimulate vagal afferent fibers, transmitting signals to the brain and modulating the neural-immune network via the CAIP. Consequently, this leads to a reduction in systemic inflammation, mitigating weight loss, alleviating multiple tissue injuries, and preventing death by modulating immune cells in the spleen. This approach addresses the critical need for noninvasive sepsis therapies, potentially improving patient outcomes. Utilizing portable ultrasound equipment with minimal thermal effects, this technique offers a safe and convenient treatment option, even for home use.

Lattice atom-bridged chemical bond interface facilitates charge transfer for boosted photoelectric response

The construction of chemical bonds at heterojunction interfaces currently presents a promising avenue for enhancing photogenerated carrier interfacial transfer. However, the deliberate modulation of these interfacial chemical bonds remains a significant challenge. In this study, we successfully established a p-n junction composed of atomic-level Pt-doped CeO2 and 2D metalloporphyrins metal-organic framework nanosheets (Pt-CeO2/CuTCPP(Fe)), which enables the realization of photoelectric enhancement by regulating the interfacial Fe-O bond and optimizing the built-in electric field. Atomic-level Pt doping in CeO2 leads to an increased density of oxygen vacancies and lattice mutation, which induces a transition in interfacial Fe-O bonds from adsorbed oxygen (Fe-OA) to lattice oxygen (Fe-OL). This transition changes the interfacial charge flow pathway from Fe-OA-Ce to Fe-OL, effectively reducing the carrier transport distance along the atomic-level charge transport highway. This results in a 2.5-fold enhancement in photoelectric performance compared with the CeO2/CuTCPP(Fe). Furthermore, leveraging the peroxidase-like activity of the p-n junction, we employed this functional heterojunction interface to develop a photoelectrochemical immunoassay for the sensitive detection of prostate-specific antigens.

{110} Surface-Exposed Bi3.15Nd0.85Ti3O12 Ferroelectric Nanosheet Arrays on Porous Ceramics as Efficient and Recyclable Piezo-Photocatalysts

Bismuth-layered ferroelectric nanomaterials exhibit great potential for piezo-photocatalysis. However, a major challenge lies in the difficulty of recovering the catalytic powders, raising concerns regarding secondary pollution of water. In this work, a novel hierarchical porous ferroelectric ceramic containing {110} surface-exposed Bi3.15Nd0.85Ti3O12 (BIT-Nd) nanosheet arrays is grown on a porous ceramic matrix for efficient and recyclable piezo-photocatalysis. By controlling the BIT-Nd loading level of the nanosheets, the piezo-photocatalytic degradation efficiency of a Rhodamine B(RhB) (C0 = 10 mg L-1) solution reached an optimum value of 97.1% in 100 min with a first-order kinetic rate constant, k, of up to 0.0321 min-1 in Bi3.15Nd0.85Ti3O12-20 (BITNd-20) with a mass ratio of hydrothermal products to ceramics of 20%. In the presence of BITNd-20, a surprising H2 yield rate of 130 µmol·h-1 is achieved without using any cocatalyst or scavenger. Specially, the beneficial role of snowflake structures on piezoelectric potential amplification and introducing nanosheets with exposed {110} surfaces on hydrogen evolution reaction (HER) activity, piezoelectric potential output, and catalytic performance of porous ceramics has been revealed. This unique design strategy provides a new approach to enhance the piezo-photocatalytic activity by addressing environmental issues and enhancing catalytic performance to yield cleaner energy.

Amorphous/Crystalline Interface of Bi/Bi4NbO8Cl Heterostructure for Improved Piezo-Photocatalysis

Efficient separation of photogenerated charges at the surface of photocatalysts is vital for achieving high photocatalytic activity. Here, a Bi/Bi4NbO8Cl heterostructure piezo-photocatalyst with an amorphous/crystalline interface (acBi/BNC) is prepared by in situ reduction using Bi4NbO8Cl as a self-sacrificial template. This ingenious design synergistically utilizes the advantages of the amorphous/crystalline interface structure, localized surface plasmon resonance effect, and piezoelectric field. The formation of amorphous/crystalline interfaces induces the generation of oxygen vacancies, and subsequently lattice distortions, thus improving the piezoelectric properties. Theoretical and experimental results demonstrate that the combination of piezoelectric field and amorphous/crystalline interface promotes the effective separation and migration of photogenerated charges between the bulk and surface of the catalysts. Under simultaneous light and ultrasound, the optimal heterostructure (acBi/BNC-3) exhibit superior photodegradation efficiency of tetracycline reached 80% within 5 min, and the reaction rate (2.78 × 10-1 min-1) is 7.8 and 5.4 times that of pure Bi4NbO8Cl (BNC) and crystalline Bi/Bi4NbO8Cl (cBi/BNC), respectively. Furthermore, the piezo-photocatalytic tetracycline degradation efficiency surpasses those under individual photocatalysis and piezocatalysis conditions. This work provides a novel rational design to improve the spatial charge separation of Bi-based catalysts and prepare high-performance piezo-photocatalysts via interface engineering.

Tailored Dynamic Seesaw Configuration of Heterojunctions to Enhance Piezo-Photocatalytic Overall Nitrogen Fixation

Relay overall nitrogen fixation presents an intriguing approach to the simultaneous production of nitric acid and ammonia. However, it remains a significant challenge due to manipulating dual active sites on both temporal and spatial mesoscopic scales. In this study, we propose a bionic seesaw Bi4O5Cl2-Bi4O5Br2 heterojunction, which establishes a one-way reaction channel through the entanglement effect, challenging the inherent idea of synchronous reaction in a heterojunction. Notably, the adaptive interface functions as a fulcrum by incorporating both tensile Bi-Cl bonds and compressive Bi-Br bonds while also inducing the localized surface lattice distortion of Bi-O to sequentially activate the active sites. Therefore, unsaturated sites and dynamic properties trigger the seesaw structure to enhance both charge exchange and molecular polarization of N2 during reduction, thereby creating a hydroxy-rich environment for the ammonia oxidation process. Our work offers a novel active site control perspective and clarifies nitrogen fixation processes.

Spatially Separated Redox Centers in Anthraquinone-grafted Metal-Organic Frameworks for Efficient Piezo-photocatalytic H2O2 Production

Piezo-photocatalytic production of hydrogen peroxide (H2O2) from water and air is promising but its large-scale application is still challenging as insufficient reaction active sites and low reaction efficiency. We have applied molecular engineering methods to design an anthraquinone molecularly (AQ) grafted metal-organic framework piezo-photocatalyst (UiO-66-AQ) for H2O2 generation from water and air. The catalyst achieves a peak H2O2 yield of 7872.4 μM g-1 h-1 by facilitating two critical reactions: single-electron water oxidation (WOR) and two-electron oxygen reduction (ORR) on spatially separated redox sites. Experiments and computational simulations reveal efficient charge separation through a ligand-to-chain transfer mechanism. Electrons and holes are selectively transferred to AQ and UiO-66 promoting ORR and WOR under ultrasound and visible light. The high reaction rate of ORR (rapid generation of endoperoxide) compensates for the slow kinetics of WOR (generation of OH*) and greatly increases the rate of full-reaction of H2O2 production. Additionally, a continuous flow tubular reactor equipped with UiO-66-AQ catalytic membranes affords 96 % removal of organic dyes by a in situFenton process under visible light and water flow, confirming the significant potential of the catalyst for practical applications. This work deepens the understanding of directional carrier migration at piezo-photocatalytic spatial separation sites, opening new pathways for environmentally friendly and efficient H2O2 synthesis.

Ocean wave-driven covalent organic framework/ZnO heterostructure composites for piezocatalytic uranium extraction from seawater

Piezoelectric catalysis possesses the potential to convert ocean wave energy into and holds broad prospects for extracting uranium from seawater. Herein, the Z-type ZnO@COF heterostructure composite with excellent piezoelectric properties was synthesized through in situ growth of covalent organic frameworks (COFs) on the surface of ZnO and used for efficient uranium extraction. The designed COFs shell enables ZnO with stability, abundant active sites and high-speed electron transport channels. Meanwhile, the interface electric field established in the heterojunctions stimulates electron transfer from COFs to ZnO, which break the edge shielding effect of the ZnO's metallic state. Additionally, the polarization of ZnO is enhanced by heterogeneous engineering, which ensures the excellent piezocatalytic performance. As a result, ZnO@COF achieves an ultra-high efficiency of 7.56 mg g-1 d-1 for uranium extraction from natural seawater driven by waves. In this work, we open an avenue for developing efficient catalysts for uranium extraction from seawater.

Oxidative Polymerization in Water Treatment: Chemical Fundamentals and Future Perspectives

For several decades, the methodology of complete destruction of organic pollutants via oxidation, i.e., mineralization, has been rooted in real water treatment applications. Nevertheless, this industrially accepted protocol is far from sustainable because of the excessive input of chemicals and/or energy as well as the unregulated carbon emission. Recently, there have been emerging studies on the removal of organic pollutants via a completely different pathway, i.e., polymerization, meaning that the target pollutants undergo oxidative polymerization reactions to generate polymeric products. These studies have collectively shown that compared to the conventional mineralization pathway, the polymerization pathway allows more efficient removal of target pollutants, largely reduced input of chemicals, and suppressed carbon emission. In this review, we aim to provide a comprehensive examination of the fundamentals of the oxidative polymerization process, current state-of-the-art strategies for regulation of the polymerization pathway from both kinetic and thermodynamic perspectives, and resource recovery of the formed polymeric products. In the end, the limitations of the polymerization process for pollutant removal are discussed, with perspectives for future studies. Hopefully, this review could not only provide critical insight for the advancement of polymerization-oriented technologies for removal of more organic pollutants in a greener manner but also stimulate more paradigm innovations for low-carbon water treatment.

Catalysis under electric-/magnetic-/electromagnetic-field coupling

The ultimate goal of catalysis is to control the cleavage and formation of chemical bonds at the molecular or even atomic level, enabling the customization of catalytic products. The essence of chemical bonding is the electromagnetic interaction between atoms, which makes it possible to directly manipulate the dynamic behavior of molecules and electrons in catalytic processes using external electric, magnetic and electromagnetic fields. In this tutorial review, we first introduce the feasibility and importance of field effects in regulating catalytic reaction processes and then outline the basic principles of electric-/magnetic-/electromagnetic-field interaction with matter, respectively. In each section, we further summarize the relevant important advances from two complementary perspectives: the macroscopic molecular motion (including translation, vibration and rotation) and the microscopic intramolecular electron state alteration (including spin polarization, transfer or excitation, and density of states redistribution). Finally, we discuss the challenges and opportunities for further development of catalysis under electric-/magnetic-/electromagnetic-field coupling.

Defect Engineering Enhancing Piezoelectric Catalytic Activity of Covalent Organic Framework Matrix Composites for Uranium Removal

Piezoelectric catalysis is an emerging green strategy, but the existing piezoelectric heterostructures are not sufficient in performance for catalytic reduction of low-reduction potential uranium under harsh conditions. This study innovatively employs a defect heterogeneous engineering strategy, wherein covalent organic frameworks (COFs) are grown in situ on the surface of zinc oxide (ZnO) via Schiff base reactions, and defects are introduced into the COF shell layer via imine exchange reactions to construct D-COF@ZnO for piezoelectric catalytic uranium removal. The comprehensive study shows that defect heterogeneous engineering increases the asymmetry induced polarization of the material to promote charge redistribution, and thus significantly improves the activity of piezoelectric catalysis. In addition, defect engineering optimizes the nanosize of D-COF@ZnO to expose a richer array of active sites, resulting in ultra-fast U(VI) removal kinetics and ultra-high removal capacity. In the actual nuclear wastewater settings, D-COF@ZnO demonstrates outstanding selective removal efficacy for uranium, manifesting its considerable application potential and efficiency superiority. This strategy holds profound implications for facilitating the application of piezoelectric catalytic technology in environmental protection domains such as uranium removal, manifesting its considerable potential and value.

Polarization: A Universal Driving Force for Energy, Environment, and Electronics

The sustainable future relies on the synergistic development of energy, environmental, and electronic systems, founded on the development of functional materials by exploring their quantum mechanisms. Effective control over the distribution and behavior of charges within these materials, a basic quantum attribute, is crucial in dictating their physical, chemical, and electronic properties. At the core of charge manipulation lies "polarization"-a ubiquitous phenomenon marked by separating positive and negative charges. This review thoroughly examines polarization techniques, spotlighting their transformative role in catalysis, energy storage, solar cells, and electronics. Starting with the foundational mechanisms underlying various forms of polarization, including piezoelectric, ferroelectric, and pyroelectric effects, the perspective is expanded to cover any asymmetric phenomena that generate internal fields, such as heterostructures and doping. Afterward, the critical role of polarization across various applications, including charge separation, surface chemistry modification, and energy band alignment, is highlighted. Special emphasis is placed on the synergy between polarization and material properties, demonstrating how this interplay is pivotal in overcoming existing technological limitations and unlocking new functionalities. Through a comprehensive analysis, a holistic roadmap is offered for harnessing polarization across the broad spectrum of applications, thus finding sustainable solutions for future energy, environment, and electronics.

Polarization-Induced Internal Electric Field-Dominated S-Scheme KNbO3-CuO Heterojunction for Photoreduction of CO2 with High CH4 Selectivity

The polarization-induced internal electric field (IEF) in ferroelectric materials could promote photogenerated charge transfer across the heterojunction interface, but the effect of polarization-induced IEF on the mechanism of photogenerated charge transfer is ambiguous. In this study, a KNbO3-CuO heterojunction was synthesized by depositing copper oxide (CuO) onto KNbO3. Incorporating CuO broadens the light absorption of KNbO3, thereby enhancing the dissociation of the photogenerated charges. The results show that the polarization-induced IEF in KNbO3 determines that the charge transport mechanism in the KNbO3-CuO heterojunction follows the S-scheme. Owing to the S-scheme heterojunctions and efficient CO2 capture and activation by CuO, the CH4 production rate of KNbO3-CuO increased by nearly 26 times compared to KNbO3. Additionally, the CH4 selectivity of KNbO3-CuO could reach up to 97.80%. This research offers valuable insights into enhancing the photogenerated charge separation and constructing heterojunctions.

Enhancement of the Piezocatalytic Response of La-Doped BiFeO3 Nanoparticles by Defects Synergy

Because of their intrinsic polarization and related properties, ferroelectrics attract significant attention to address energy transformation and environmental protection. Here, by using trivalent-ion-lanthanum doping of BiFeO3 nanoparticles (NPs), it is shown that defects and piezoelectric potential are synergized to achieve a high piezocatalytic effect for decomposing the model Rhodamine B (RhB) pollutant, reaching a record-high piezocatalytic rate of 21 360 L mol-1 min-1 (i.e., 100% RhB degradation within 20 min) that exceeds most state-of-the art ferroelectrics. The piezocatalytic Bi0.99La0.01FeO3 NPs are also demonstrated to be versatile toward various pharmaceutical pollutants with over 90% removal efficiency, making them extremely efficient piezocatalysts for water purification. It is also shown that 1% La-doping introduces oxygen vacancies and Fe2+ defects. It is thus suggested that oxygen vacancies act as both active sites and charge providers, permitting more surface adsorption sites for the piezocatalysis process, and additional charges and better energy transfer between the NPs and surrounding molecules. Furthermore, the oxygen vacancies are proposed to couple to Fe2+ to form defect dipoles, which in turn introduces an internal field, resulting in more efficient charge de-trapping and separation when added to the piezopotential. This synergistic mechanism is believed to provide a new perspective for designing future piezocatalysts with high performance.

CuCo2S4 nanoparticles synthesized via a thermal decomposition approach: evaluation of their potential as peroxidase mimics

The current study demonstrates the synthesis of CuCo2S4 nanoparticles using a novel thermal decomposition approach. The CuCo2S4 nanoparticles were synthesized under various conditions by changing the source of sulfur and the solvent. The CuCo2S4 nanoparticles were characterized using an array of analytical techniques. Powder XRD results indicate the successful formation of CuCo2S4 nanoparticles. TEM results show agglomerated nanoparticles with close to spherical morphology and XPS measurements indicate the presence of Cu2+, Cu+, Co3+, Co2+, and S2- in the samples. The CuCo2S4 nanoparticles exhibit weak ferromagnetic and paramagnetic behaviour at 5 K and 300 K, respectively. The CuCo2S4 nanoparticles were explored for their enzyme mimetic activity using 3,3',5,5' tetramethylbenzidine (TMB) as a substrate. They exhibit better catalytic activity compared to that of a natural enzyme (horseradish peroxidase) and other metal sulfide nanoparticles reported in the literature.

Piezoelectric Bilayer Nickel-Iron Layered Double Hydroxide Nanosheets with Tumor Microenvironment Responsiveness for Intensive Piezocatalytic Therapy

Piezocatalytic therapy (PCT) based on 2D layered materials has emerged as a promising non-invasive tumor treatment modality, offering superior advantages. However, a systematic investigation of PCT, particularly the mechanisms underlying the reactive oxygen species (ROS) generation by 2D nanomaterials, is still in its infancy. Here, for the first time, biodegradable piezoelectric 2D bilayer nickel-iron layered double hydroxide (NiFe-LDH) nanosheets (thickness of ≈1.86 nm) are reported for enhanced PCT and ferroptosis. Under ultrasound irradiation, the piezoelectric semiconducting NiFe-LDH exhibits a remarkable ability to generate superoxide anion radicals, due to the formation of a built-in electric field that facilitates the separation of electrons and holes. Notably, the significant excitonic effect in the ultrathin NiFe-LDH system enables long-lived excited triplet excitons (lifetime of ≈5.04 µs) to effectively convert triplet O2 molecules into singlet oxygen. Moreover, NiFe-LDH exhibited tumor microenvironment (TME)-responsive peroxidase (POD)-like and glutathione (GSH)-depleting capabilities, further enhancing oxidative stress in tumor cells and inducing ferroptosis. To the best of knowledge, this is the first report on piezoelectric semiconducting sonosensitizers based on LDHs for PCT and ferroptosis, providing a comprehensive understanding of the piezocatalysis mechanism and valuable references for the application of LDHs and other 2D materials in cancer therapy.

Single-Particle Imaging Photoinduced Charge Transfer of Ferroelectric Polarized Heterostructures for Photocatalysis

Piezoelectric-assisted photocatalysis has a huge potential in solving the energy shortage and environmental pollution problems, and imaging their detailed charge-transfer process can provide in-depth understanding for the development of high-active piezo-photocatalysts; however, it is still challenging. Herein, topotactic heterostructures of TiO2@BaTiO3 (TO@BTO-S) were constructed by the epitaxial growth of ferroelectric BaTiO3 mesocrystals on TiO2-{001} facets, resulting in a ferroelectric photocatalyst with a polarization orientation on the surface. Notably, the photoinduced charge transfer in ferroelectric TiO2@BaTiO3 was accurately monitored and directly visualized at the single-particle level by the advanced photoluminescence (PL) imaging microscopy systems. The longer PL lifetime of TO@BTO-S demonstrated the efficient charge separation caused by a built-in electric field, which is constructed by the polarization orientation of BaTiO3 mesocrystals. Therefore, the TO@BTO-S heterostructure exhibits efficient piezoelectric-assisted photocatalytic pure water splitting, which is 290 times higher than photocatalysis. This work revealed time/spatial-resolved photoinduced charge transfer in piezoelectric assistance photocatalysts at the single-particle level and demonstrated the great role of polarization orientation in promoting charge transfer for photocatalysis.

Pd Nanoparticle-Modified BiOBr/CdS S-Scheme Photocatalyst for Enhanced Conversion of CO2

S-scheme heterojunction photocatalyst-coupled plasma-resonance effect can enhance the response range and absorption of light and charge transfer, and, at the same time, obtain strong redox ability, which is an effective way to improve CO2 conversion. In this work, plasma S-scheme heterojunctions of Pd/BiOBr/CdS with heterogeneous interfaces have been successfully constructed by a simple hydrothermal method. The possible reaction mechanism was proposed by in situ infrared, ultraviolet-visible spectroscopy (UV-vis), electron paramagnetic resonance (ESR), density functional theory (DFT), and electrochemical techniques. It was proved that the plasma S-scheme heterojunction can enhance the charge separation efficiency and improve the photocatalytic activity. When the loading ratio is Pd0.6-10%-BiOBr/CdS, it has the best performance, and the CO yield is 30.24 μmol/g, which is 15 and 30 times that of pure BiOBr and CdS, respectively. The results show that with the strong absorption of photon energy and the special electron transfer mode of S-scheme heterojunction, the charge can be effectively separated and transferred, and the photocatalytic activity is significantly improved. This study provides a useful strategy for charge transfer kinetics of plasma S-scheme heterojunction photocatalysts.

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

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

Preparation of hollow double-layer Pt@CeO2 nanospheres as oxidase mimetics for the colorimetric-fluorescent-SERS triple-mode detection of glutathione in serum

Glutathione (GSH) is an essential antioxidant in the human body, but its detection is difficult due to the interference of complex components in serum. Herein, hollow double-layer Pt@CeO2 nanospheres were developed as oxidase mimetics, and the light-assisted oxidase mimetics effects were found. The oxidase activity was enhanced significantly by utilizing the synergistic effect of Schottky junction and the localized surface plasmon resonance (LSPR) of Pt under UV light. A novel GSH colorimetric-fluorescent-SERS sensing platform was established, with the sensing performance notably boosted by using the light-assisted oxidase mimetics effects. This platform boasts an exceptionally low detection limit (LOD) of 0.084 μM, while the detection time was shortened from 10 min to just 2 min. The anti-interference detection with high recovery rate (96.84%-107.4 %) in real serum made it be promising for practical application.

Hollow Cu2-xS@NiFe Layered Double Hydroxide Core-Shell S-Scheme Heterojunctions with Broad-Spectrum Response and Enhanced Photothermal-Photocatalytic Performance

Designing a reasonable heterojunction is an efficient path to improve the separation of photogenerated charges and enhance photocatalytic activity. In this study, Cu2-xS@NiFe-LDH hollow nanoboxes with core-shell structure are successfully prepared. The results show that Cu2-xS@NiFe-LDH with broad-spectrum response has good photothermal and photocatalytic activity, and the photocatalytic activity and stability of the catalyst are enhanced by the establishment of unique hollow structure and core-shell heterojunction structure. Transient PL spectra (TRPL) indicates that constructing Cu2-xS@NiFe-LDH heterojunction can prolong carrier lifetime obviously. Cu2-xS@NiFe-LDH shows a high photocatalytic hydrogen production efficiency (5176.93 µmol h-1 g-1), and tetracycline degradation efficiency (98.3%), and its hydrogen production rate is ≈10-12 times that of pure Cu2-xS and NiFe-LDH. In situ X-ray photoelectron spectroscopy (XPS) and electron spin resonance (ESR) provide proofs of the S-scheme electron transfer path. The S-scheme heterojunction achieves high spatial charge separation and exhibits strong photoredox ability, thus improving the photocatalytic performance.

Piezo-catalysis in BiFeO3@In2Se3 Heterojunction for High-Efficiency Uranium Removal

Piezo-catalysis emerges as an efficient, safe, and affordable strategy for removing hazardous substances from aquatic environments. Here, the BiFeO3@In2Se3 heterojunction demonstrates remarkable prowess as a piezo-catalyst, enabling the high-efficiency removal of uranium (U) from U(VI)-containing water. A total U(VI) removal efficiency of 94.6% can be achieved under ultrasonic vibration without any sacrificial agents. During the entire catalytic process, piezo-induced electrons, hydroxyl radicals, and superoxide radicals play important roles in U(VI) removal, while the generated H2O2 is responsive to the transformation of soluble U(VI) into insoluble (UO2)O2•2H2O and UO3. Furthermore, auxiliary illumination can accelerate the increase of free charges, enabling the piezo-catalyst to retain more charges. This leads to an improved U(VI) removal efficiency of 98.8% and a significantly increased reaction rate constant. This study offers a comprehensive analysis of the fabrication of high-efficiency piezo-catalysts in the removal or extraction of U(VI) from U(VI)-containing water.

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.

Piezo-enhanced near infrared photocatalytic nanoheterojunction integrated injectable biopolymer hydrogel for anti-osteosarcoma and osteogenesis combination therapy

Preventing local tumor recurrence while promoting bone tissue regeneration is an urgent need for osteosarcoma treatment. However, the therapeutic efficacy of traditional photosensitizers is limited, and they lack the ability to regenerate bone. Here, a piezo-photo nanoheterostructure is developed based on ultrasmall bismuth/strontium titanate nanocubes (denoted as Bi/SrTiO3), which achieve piezoelectric field-driven fast charge separation coupling with surface plasmon resonance to efficiently generate reactive oxygen species. These hybrid nanotherapeutics are integrated into injectable biopolymer hydrogels, which exhibit outstanding anticancer effects under the combined irradiation of NIR and ultrasound. In vivo studies using patient-derived xenograft models and tibial osteosarcoma models demonstrate that the hydrogels achieve tumor suppression with efficacy rates of 98.6 % and 67.6 % in the respective models. Furthermore, the hydrogel had good filling and retention capabilities in the bone defect region, which exerted bone repair therapeutic efficacy by polarizing and conveying electrical stimuli to the cells under mild ultrasound radiation. This study provides a comprehensive and clinically feasible strategy for the overall treatment and tissue regeneration of osteosarcoma.

Construction of MXene/Bi2WO6 Schottky Junction for Highly Efficient Piezocatalytic Hydrogen Evolution and Unraveling Mechanism

For the first time, a series of MXene (Ti3C2Tx)/Bi2WO6 Schottky junction piezocatalysts were constructed, and the piezocatalytic hydrogen evolution activity was explored. Optimal Ti3C2Tx/Bi2WO6 exhibits the highest piezocatalytic hydrogen evolution rate of 764.4 μmol g-1 h-1, which is nearly 8 times higher than that of pure Ti3C2Tx and twice as high as that of Bi2WO6. This value also surpasses that of most recently reported typical piezocatalysts. Moreover, related experimental results and density functional theory calculations reveal that Ti3C2Tx/Bi2WO6 can provide unique channels for efficient electron transfer, enhance piezoelectric properties, optimize the adsorption Gibbs free energy of water, reduce activation energy for hydrogen atoms, endow robust separation capacity of charge carrier, and restrict the electron-hole recombination rate, thus significantly promoting the efficiency of hydrogen evolution reaction. Ultimately, we have unraveled an innovative piezocatalytic mechanism. This work broadens the scope of MXene materials in a sustainable energy piezocatalysis application.

The dual built-in electric fields across CoS/MoS2 heterojunctions for energy-saving hydrogen production coupled with sulfion degradation

Substituting the sluggish oxygen evolution reaction with the sulfur oxidation reaction can significantly reduce energy consumption and eliminate environmental pollutants during hydrogen generation. However, the progress of this technology has been hindered due to the lack of cost-effective, efficient, and durable electrocatalysts. In this study, we present the design and construction of a hierarchical metal sulfide catalyst with a gradient structure comprising nanoparticles, nanosheets, and microparticles. This was achieved through a structure-breaking sulfuration strategy, resulting in a "ball of yarn"-like core/shell CoS/MoS2 microflower with CoS/MoS2/CoS dual-heterojunctions. The difference in work functions between CoS and MoS2 induces an electron polarization effect, creating dual built-in electric fields at the hierarchical interfaces. This effectively modulates the adsorption behavior of catalytic intermediates, thereby reducing the energy barrier for catalytic reactions. The optimized catalyst exhibits outstanding electrocatalytic performance for both the hydrogen evolution reaction and the sulfur oxidation reaction. Remarkably, in the assembled electrocatalytic coupling system, it only requires a cell voltage of 0.528 V at 10 mA cm-2 and maintains long-term durability for over 168 h. This work presents new opportunities for low-cost hydrogen production and environmentally friendly sulfion recycling.

Ultrasound-activated piezo-hot carriers trigger tandem catalysis coordinating cuproptosis-like bacterial death against implant infections

Implant-associated infections due to the formation of bacterial biofilms pose a serious threat in medical healthcare, which needs effective therapeutic methods. Here, we propose a multifunctional nanoreactor by spatiotemporal ultrasound-driven tandem catalysis to amplify the efficacy of sonodynamic and chemodynamic therapy. By combining piezoelectric barium titanate with polydopamine and copper, the ultrasound-activated piezo-hot carriers transfer easily to copper by polydopamine. It boosts reactive oxygen species production by piezoelectrics, and facilitates the interconversion between Cu2+ and Cu+ to promote hydroxyl radical generation via Cu+ -catalyzed chemodynamic reactions. Finally, the elevated reactive oxygen species cause bacterial membrane structure loosening and DNA damage. Transcriptomics and metabolomics analysis reveal that intracellular copper overload restricts the tricarboxylic acid cycle, promoting bacterial cuproptosis-like death. Therefore, the polyetherketoneketone scaffold engineered with the designed nanoreactor shows excellent antibacterial performance with ultrasound stimulation and promotes angiogenesis and osteogenesis on-demand in vivo.

Unraveling Synergistic Effect of Defects and Piezoelectric Field in Breakthrough Piezo-Photocatalytic N2 Reduction

Piezo-photocatalysis is a frontier technology for converting mechanical and solar energies into crucial chemical substances and has emerged as a promising and sustainable strategy for N2 fixation. Here, for the first time, defects and piezoelectric field are synergized to achieve unprecedented piezo-photocatalytic nitrogen reduction reaction (NRR) activity and their collaborative catalytic mechanism is unraveled over BaTiO3 with tunable oxygen vacancies (OVs). The introduced OVs change the local dipole state to strengthen the piezoelectric polarization of BaTiO3 , resulting in a more efficient separation of photogenerated carrier. Ti3+ sites adjacent to OVs promote N2 chemisorption and activation through d-π back-donation with the help of the unpaired d-orbital electron. Furthermore, a piezoelectric polarization field could modulate the electronic structure of Ti3+ to facilitate the activation and dissociation of N2 , thereby substantially reducing the reaction barrier of the rate-limiting step. Benefitting from the synergistic reinforcement mechanism and optimized surface dynamics processes, an exceptional piezo-photocatalytic NH3 evolution rate of 106.7 µmol g-1  h-1 is delivered by BaTiO3 with moderate OVs, far surpassing that of previously reported piezocatalysts/piezo-photocatalysts. New perspectives are provided here for the rational design of an efficient piezo-photocatalytic system for the NRR.

Macroscopic Spontaneous Piezopolarization and Oxygen-Vacancy Coupled Robust NaNbO3/FeOOH Heterojunction for Pharmaceutical Drug Degradation and O2 Evolution: Combined Experimental and Theoretical Study

Prompt recombination of photoproduced charges in bulk and surface of a photocatalyst significantly impedes catalytic efficiency. To address these challenges, FeOOH nanorods (NRs) anchored NaNbO3 (NNO) piezoelectric microcubes (MCs) have been fabricated for ciprofloxacin (CIP) degradation and oxygen evolution through water splitting by coupling macroscopic spontaneous piezoelectric polarization and a built-in electric field. The local electric field induced by surface oxygen vacancies (Ovs) and orientation of FeOOH NRs over NNO MCs afford the polarization electric field a significant boost, driving the quick separation/migration of charge carriers from bulk to the surface. The polarized NNO/FeOOH composite with ample Ovs demonstrates an outstanding piezophotocatalytic CIP degradation of 93% in 1 h, higher than pristine materials (NNO and FeOOH), and a high O2 evolution rate of 1155 μmol h-1. The effect of piezoelectric polarization on the catalytic activity is supplemented by theoretical simulations. This work offers an avenue for selective pollutant remediation and water splitting through the rational design of piezoelectric polarization-mediated heterostructure systems with surface Ovs.

Intrinsic Polarized Electric Field Induces a Storing Mechanism to Achieve Energy Storing Catalysis in V2 C MXene

Efficient storage and separation of holes and electrons pose significant challenges for catalytic reactions, particularly in the context of single-phase catalysis. Herein, V2 C MXene, with its intrinsic polarized electric field, successfully overcomes this obstacle. To enhance hole storage, a multistep etching process is employed under reducing conditions to control the content of surface termination groups, thus exposing more defective active sites. The intrinsically polarized electric field confines holes to the surface of the layer and free electrons within the layer, leading to a lag in e- release compared to h+ . The quantities of stored holes and electrons are measured to be 18.13 µmol g-1 and 106.37 µmol g-1 , respectively. Under dark, V2 C demonstrates excellent and stable dark-catalytic performance, degrading 57.91% of tetracycline (TC 40 mg L-1 ) and removing 23% of total organic carbon (TOC) after 140 min. In simulated sunlight and near-infrared light, the corresponding degradation rates reach 72.24% and 79.54%, with corresponding TOC removal rates of 49% and 48%, respectively. The hole and electron induced localized surface plasmon resonance (LSPR) effects contribute to a long-lasting and enhanced broad-spectrum mineralization of V2 C MXene. This study provides valuable insights into the research and application of all-weather MXene energy storage catalytic materials.

Two-dimensional ternary pentagonal BCX (X = P, As, and Sb): promising photocatalyst semiconductors for water splitting with strong piezoelectricity

Seeking high-performance energy conversion materials is one of the most important issues in designing 2D materials. In the framework of density functional theory, we propose a series of ternary monolayers, penta-BCX (X = P, As, and Sb), and systematically investigate their structural stability, mechanical, piezoelectric, and photocatalytic properties. All three materials are semiconductors with a bandgap ranging from 2.56 eV to 3.24 eV, so they could be promising catalysts for the photolysis of water. Penta-BCX exhibits significant piezoelectric properties attributed to their non-centrosymmetric structure and low in-plane Young's modulus, which are expected to efficiently drive photocatalytic water decomposition. Moreover, the bandgap, band edge position, and light absorption of penta-BCX can be modulated by tensile or compressive strain to enhance their photocatalytic performance in the visible light and ultraviolet regions.

Defective ReS2 Triggers High Intrinsic Piezoelectricity for Piezo-Photocatalytic Efficient Sterilization

Rhenium disulfide (ReS2) is a promising piezoelectric catalyst due to its excellent electron transfer ability and abundant unsaturated sites. The 1T' phase structure leads to the evolution of ReS2 into a centrosymmetric spatial structure, which restricts its application in piezoelectric catalysis. Herein, we propose a controllable defect engineering strategy to trigger the piezoelectric response of ReS2. The introduction of vacancy defects disrupts the initial centrosymmetric structure, which breaks the piezoelectric polarization bond and generates piezoelectric properties. By using transmission electron microscopy, we characterized it at the atomic scale and determined that vacancy defects contribute to an excellent piezoelectric property through first-principles calculations. Notably, the piezoelectric coefficient of the catalyst with 40 s-etching (ReS2@C-40) is 23.07 pm/V, an order of magnitude greater than other transition metal dichalcogenides. It demonstrated the feasibility of optimizing piezoelectric properties by increasing the conformational asymmetry. Based on its remarkable piezoelectric activity, ReS2@C-40 exhibits highly efficient piezo-photocatalytic synergistic sterilization performance with 99.99% eradication of Escherichia coli and 96.67% of Staphylococcus aureus within 30 min. This pioneering research on the coupling effect of ReS2 in piezoelectric catalysis and photocatalysis provides ideas for the development of piezo-photocatalysts and efficient water purification technologies.

A highly reversible force-assisted Li - CO2 battery based on piezoelectric effect of Bi0.5Na0.5TiO3 nanorods

The use of light-assisted cathode is regarded as an effective approach to reduce the overpotential of lithium carbon dioxide (Li - CO2) batteries. However, the inefficient electron-hole separation and the complex discharge-charge reactions hamper the efficiency of CO2 photocatalytic reaction in battery. Herein, a highly reversible force-assisted Li - CO2 battery has been established for the first time by employing a Bi0.5Na0.5TiO3 nanorods piezoelectric cathode. The high-energy electron and holes generated by the piezoelectric cathode with ultrasonic force can effectively enhance the carbon dioxide reduction reaction (CDRR) and carbon dioxide evolution reaction (CDER) kinetics, thereby reducing the overpotentials during the discharge-charge processes. Moreover, the morphology of the discharge product (Li2CO3) can be modified via the dense surface electrons of the piezoelectric cathode, resulting in the promoted decomposition kinetics of Li2CO3 in charging progress. Thus, the force-assisted Li - CO2 battery with the unique piezoelectric cathode can adjust the output and input energy by ultrasonic wave, and provides an ultra-low charging platform of 3.52 V, and exhibits excellent cycle stability (a charging platform of 3.42 V after 100 h cycles). The investigation of the force-assisted process described herein provides significant insights to solve overpotential in the Li - CO2 batteries system.

Free-Electron Inversive Modulation to Charge Antibonding Orbital of ReS2 Cocatalyst for Efficient Photocatalytic Hydrogen Generation

The free electron transfer between cocatalyst and photocatalyst has a great effect on the bonding strength between the active site and adsorbed hydrogen atom (Hads ), but there is still a lack of effective means to purposely manipulate the electron transfer in a beneficial direction of H adsorption/desorption activity. Herein, when ReSx cocatalyst is loaded on TiO2 surface, a spontaneous free-electron transfer from ReSx to TiO2 happens due to the smaller work function of ReSx , causing an over-strong S-Hads bond. To prevent the over-strong S-Hads bonds of ReSx in the ReSx /TiO2 , a free-electron reversal transfer strategy is developed to weaken the strong S-Hads bonds via increasing the work function of ReSx by incorporating O to produce ReOSx cocatalyst. Research results attest that a larger work function of ReOSx than that of TiO2 can induce reversal transfer of electrons from TiO2 to ReOSx to produce electron-rich S(2+δ)- , causing the increased antibonding-orbital occupancy of S-Hads in ReOSx /TiO2 . Accordingly, the stability of adsorbed H on S sites is availably decreased, thus weakening the S-Hads of ReOSx . In this case, an electron-rich S(2+δ)- -mediated "capture-hybridization-conversion" mechanism is raised . Benefiting from such property, the resultant ReOSx /TiO2 photocatalyst exhibits a superior H2 -evolution rate of 7168 µmol h-1 g-1 .

Pulsed-Laser-Triggered Piezoelectric Photocatalytic CO2 Reduction over Tetragonal BaTiO3 Nanocubes

The recombination of photoinduced carriers in photocatalysts is considered one of the biggest barriers to the increase of photocatalytic efficiency. Piezoelectric photocatalysts open a new route to realize rapid carrier separation by mechanically distorting the lattice of piezoelectric nanocrystals to form a piezoelectric potential within the nanocrystals, generally requiring external force (e.g., ultrasonic radiation, mechanical stirring, and ball milling). In this study, a low-power UV pulsed laser (PL) (3 W, 355 nm) as a UV light source can trigger piezoelectric photocatalytic CO2 reduction of tetragonal BaTiO3 (BTO-T) in the absence of an applied force. The tremendous transient light pressure (5.7 × 107  Pa, 2.7 W) of 355 nm PL not only bends the energy band of BTO-T, thus allowing reactions that cannot theoretically occur to take place, but also induces a pulsed built-in electric field to determine an efficient photoinduced carrier separation. On that basis, the PL-triggered piezoelectric photocatalytic CO2 reduction realizes the highest reported performance, reaching a millimole level CO yield of 52.9 mmol g-1 h-1 and achieving efficient photocatalytic CO2 reduction in the continuous catalytic system. The method in this study is promising to contribute to the design of efficient piezoelectric photocatalytic reactions.

Conductive Polymer-Inorganic Polythiophene/Cd0.5Zn0.5S Heterojunction with Apace Charge Separation and Strong Light Absorption for Boosting Photocatalytic Activity

In order to utilize the synergistic effect between a conductive polymer and an inorganic semiconductor to efficaciously enhance charge transfer and solve the problem of unsatisfactory performance of a single photocatalyst, thiophene (Th) was polymerized on the Cd0.5Zn0.5S nanoparticle surface to prepare a conductive polymer-inorganic polythiophene/Cd0.5Zn0.5S (PTh/CZS) heterostructrue through a simple in situ oxidation polymerization for the first time. The as-prepared PTh/CZS heterostructures significantly improved photocatalytic TCH degradation and hydrogen production activities. Especially, the 15PTh/CZS sample exhibited the optimal hydrogen production rate (18.45 mmol g-1 h-1), which was 2.51 times higher than pure Cd0.5Zn0.5S nanoparticles. In addition, 15PTh/CZS also showed very fast and efficient photodegradation ability for degrading 88% of TCH in 25 min. Moreover, the degradation rate (0.06229 min-1) was five times more than that of Cd0.5Zn0.5S. The π-π* transition characteristics, high optical absorption coefficient, wide absorption wavelength of PTh, the tight contact interface, and synergistic effect of PTh and Cd0.5Zn0.5S efficiently boosted charge transfer rate and increased the light absorption of PTh/CZS photocatalysts, which greatly enhanced the photocatalytic abilities. Besides, the mechanism of improved photocatalytic activities for TCH degradation and H2 production was also carefully proposed. Undoubtedly, this work would provide new insights into coupling conductive polymers to inorganic photocatalysts for achieving multifunctional applications in the field of photocatalysis.

Piezoelectricity ameliorates high-valent iron oxo species production in peroxymonosulfate activation for refractory atrazine remediation

Over the past few years, high-valent iron oxo species (Fe(IV)) have shown considerable promise. However, an improved solution is needed for the bottleneck of unsatisfactory electron transfer efficiency in Fe-based catalyst/PMS systems. In this study, Enteromorpha-derived biochar was pyrolyzed with iron and barium titanate (FeBCBa). Under ultrasonic treatment, it removes 94.5% of atrazine (10 mg/L) within 60 min, and is environmentally friendly. BaTiO3's piezoelectricity enhances Fe(IV) production in FeBCBa, resulting in superior performance. In the ultrasonic condition, the apparent reaction rate was 1.42 times higher than in the non-ultrasonic condition. Using density functional theory calculations, it can be shown that due to the Fe dopant, electrons in ATZ's LUMO are more easily transferred to the catalyst's HOMO, which is beneficial for ATZ removal. The results of this study provide new guidance for constructing stable and efficient catalysts for environmental remediation.

Integration of Single-Atom Catalyst with Z-Scheme Heterojunction for Cascade Charge Transfer Enabling Highly Efficient Piezo-Photocatalysis

Piezo-assisted photocatalysis (namely, piezo-photocatalysis), which utilizes mechanical energy to modulate spatial and energy distribution of photogenerated charge carriers, presents a promising strategy for molecule activation and reactive oxygen species (ROS) generation toward applications such as environmental remediation. However, similarly to photocatalysis, piezo-photocatalysis also suffers from inferior charge separation and utilization efficiency. Herein, a Z-scheme heterojunction composed of single Ag atoms-anchored polymeric carbon nitride (Ag-PCN) and SnO2- x is developed for efficient charge carrier transfer/separation both within the catalyst and between the catalyst and surface oxygen molecules (O2 ). As revealed by charge dynamics analysis and theoretical simulations, the synergy between the single Ag atoms and the Z-scheme heterojunction initiates a cascade electron transfer from SnO2- x to Ag-PCN and then to O2 adsorbed on Ag. With ultrasound irradiation, the polarization field generated within the piezoelectric hybrid further accelerates charge transfer and regulates the O2 activation pathway. As a result, the Ag-PCN/SnO2- x catalyst efficiently activates O2 into ·O2 - , ·OH, and H2 O2 under co-excitation of visible light and ultrasound, which are consequently utilized to trigger aerobic degradation of refractory antibiotic pollutants. This work provides a promising strategy to maneuver charge transfer dynamics for efficient piezo-photocatalysis by integrating single-atom catalysts (SACs) with Z-scheme heterojunction.

Engineering Sub-Nanometer Hafnia-Based Ferroelectrics to Break the Scaling Relation for High-Efficiency Piezocatalytic Water Splitting

Reversible control of ferroelectric polarization is essential to overcome the heterocatalytic kinetic limitation. This can be achieved by creating a surface with switchable electron density; however, owing to the rigidity of traditional ferroelectric oxides, achieving polarization reversal in piezocatalytic processes remains challenging. Herein, sub-nanometer-sized Hf0.5 Zr0.5 O2 (HZO) nanowires with a polymer-like flexibility are synthesized. Oxygen K-edge X-ray absorption spectroscopy and negative spherical aberration-corrected transmission electron microscopy reveal an orthorhombic (Pca21 ) ferroelectric phase of the HZO sub-nanometer wires (SNWs). The ferroelectric polarization of the flexible HZO SNWs can be easily switched by slight external vibration, resulting in dynamic modulation of the binding energy of adsorbates and thus breaking the "scaling relationship" during piezocatalysis. Consequently, the as-synthesized ultrathin HZO nanowires display superb water-splitting activity, with H2 production rate of 25687 µmol g-1  h-1 under 40 kHz ultrasonic vibration, which is 235 and 41 times higher than those of non-ferroelectric hafnium oxides and rigid BaTiO3 nanoparticles, respectively. More strikingly, the hydrogen production rates can reach 5.2 µmol g-1  h-1 by addition of stirring exclusively.

Harnessing ultrasound in photocatalysis: Synthesis and piezo-enhanced effect: A review

The photocatalytic technique has drawn far-ranging interests in addressing the current issues; however, its property suffers from the limited visible light response and rapid recombination of carriers. To address these issues, two specific approaches have been proposed to enhance the photocatalytic activity: (1) ultrasound-assisted synthesis has been utilized to prepare photocatalysts, resulting in refined grain size, increased specific surface area, and reduced photogenerated carrier recombination; (2) sonophotocatalysis and piezoelectric enhanced photocatalysis have been developed to accelerate the reaction, which utilizes the synergism between ultrasound and light. On one side, sonophotocatalysis generates cavitation bubbles which induce more reactive radicals for redox reactions. On the other side, ultrasound induces deformation of the piezoelectric material structure, which changes the internal piezoelectric potential and improves the photocatalytic performance. Currently, intensive efforts have been devoted to related research and great progress has been reached with applications in pollutant degradation, new energy production, and other fields. This work starts by elucidating the fundamental concept of ultrasound-assisted photocatalyst synthesis and photocatalysis. Then, the synergistic behavior between ultrasonic and light in ultrasonic-assisted photocatalysis has been thoroughly discussed, including pollutant degradation, water splitting, and bacterial sterilization. Finally, the challenge and outlook are investigated and proposed.

Environmental energy enhanced solar-driven evaporator with spontaneous internal convection for highly efficient water purification

Solar-driven interfacial evaporation for water purification is limited by the structural design of the solar evaporator and, more importantly, by the inability to separate the water from volatile organic compounds (VOCs) present in the water source. Here, we report a three-dimensional (3D) bifunctional evaporator based on N-doped carbon (CoNC/CF), which enables the separation of fresh water from VOCs by activating PMS during the evaporation process with a VOC removal rate of 99%. There is abundant van der Waals interaction between peroxymonosulfate (PMS) and CoNC/CF, and pyrrolic N is confirmed as the active site for binding phenol, thus contributing to the separation of phenol from water. With the advantageous features of sufficient light absorption, adequate water storage capacity, and spontaneous internal convection flow on its top surface, the 3D evaporator achieves a high evaporation rate under one sun (1 kW/m2) at 3.16 kg/m2/h. More notably, through careful structural design, additional energy from the environment and water can be utilized. With such a high evaporation rate and satisfactory purification performance, this work is expected to provide a promising platform for wastewater treatment.

In Situ Fabrication of a 2D/2D MXene/CN Heterojunction for Photothermally Assisted Photocatalytic Sterilization under Visible Light Irradiation

Constructing an efficient visible light-responsive antibacterial material for water treatment remains a principal goal yet is a huge challenge. Herein, a 2D/2D heterojunction composite with robust interfacial contact, named MXene/CN (MCN), was controllably fabricated by using a urea molecule intercalated into MXene following an in situ calcination method, which can realize the rapid separation and migration of photogenerated carriers under visible light irradiation and significantly improve the carrier concentration of the MXene surface, thus generating more reactive oxygen species. The generation of heat induced by MXene could also increase photogenic electron activity to facilitate the photocatalytic reaction using in situ time-resolved photoluminescence characterization. The visible light-activated germicide exhibits a sterilization efficacy against Escherichia coli of 99.70%, higher than those of pure CN (60.21%) and MXene (31.75%), due to the effect of photothermally assisted photocatalytic treatment. This work is an attempt to construct a visible light-driven antimicrobial material using Schottky junctions achieving photothermally assisted photocatalytic disinfection.

Supported TiO2-ZnWO4 Photocatalytic Nanofibrous Membranes for Flow-Through and Fixed-Bed Reactors

We developed utilization models of supported electrospun TiO2-ZnWO4 photocatalytic nanofibrous membranes for air and water purifications using a noncomplex system with facile adaptation for large-scale processes. For this uniquely designed and multimode catalyst, ZnWO4 is selected for a visible light activity, while TiO2 is incorporated to enhance physical stability. Morphological structures of the TiO2-ZnWO4 membrane are characterized by scanning electron microscopy and scanning electron microscopy-energy-dispersive X-ray spectroscopy. The distinguished growth of ZnWO4 nanorods at the surface of the TiO2-ZnWO4 membrane is revealed by transmission electron microscopy (TEM). The relaxation process and charge transfer mechanism are proposed following the examination of interface and band gap (2.76 eV) between TiO2 and ZnWO4 particles via HR-TEM and UV-vis spectrophotometry. For the gas-phase reaction, a transparent photocatalytic converter is designed to support the pleated TiO2-ZnWO4 membrane for toluene decomposition under visible light. To obtain a crack-free and homogeneous fiber structure of the pleated TiO2-ZnWO4 membrane, 1 h of nanofibrous membrane fabrication via a Nanospider machine is required. On the other hand, a fiberglass-supported TiO2-ZnWO4 membrane is fabricated as a fixed-bed photocatalyst membrane for methylene blue decomposition under natural sunlight. It is observed that using the calcination temperature at 800 °C results in the formation of metal complexes between fiber glass and the TiO2-ZnWO4 membrane. The TiO2-ZnWO4 membrane successfully decomposes toluene vapor up to 40% under a continuous-flow circumstance in a borosilicate photocatalytic converter and 70% for methylene blue in solution within 3 h. Finally, the mechanically robust and supported TiO2-ZnWO4 nanofibrous membranes are proven for an alternate potential in environmental remediation.

Multi-heteroatom-doping promotes molecular oxygen activation on polymeric carbon nitride for simultaneous generation of H2O2 and degradation of oxcarbazepine

Simultaneously realizing the efficient generation of H₂O₂ and degradation of pollutants is of great significance for environmental remediation. However, most polymeric semiconductors only show moderate performance in molecular oxygen (O₂) activation due to the sluggish electron-hole pair dissociation and charge transfer dynamics. Herein, we develop a simple thermal shrinkage strategy to construct multi-heteroatom-doped polymeric carbon nitride (K, P, O-CN_x). The resultant K, P, O-CN_x not only improves the separation efficiency of charge carriers, but also improves the adsorption/activation capacity of O₂. K, P, O-CN_x significantly increases the production of H₂O₂ and the degradation activity of oxcarbazepine (OXC) under visible light. K, P, O-CN₅ shows a high H₂O₂ production rate (1858 μM h^-1 g^-1) in water under visible light, far surpassing that of pure PCN. The apparent rate constant for OXC degradation by K, P, O-CN₅ increases to 0.0491 min^-1, which is 8.47 times that of PCN. Density functional theory (DFT) calculations show that the adsorption energy of O₂ near phosphorus atoms in K, P, O-CN_x is the highest. This work provides a new idea for the efficient degradation of pollutants and generation of H₂O₂ at the same time.

Superexchange-induced Pt-O-Ti3+ site on single photocatalyst for efficient H2 production with organics degradation in wastewater

Efficient photocatalytic H2 production from wastewater instead of pure water is a dual solution to the environmental and energy crisis, but due to the rapid recombination of photoinduced charge in the photocatalyst and inevitable electron depletion caused by organic pollutants, a significant challenge of dual-functional photocatalysis (simultaneous oxidative and reductive reactions) in single catalyst is designing spatial separation path for photogenerated charges at atomic level. Here, we designed a Pt-doped BaTiO3 single catalyst with oxygen vacancies (BTPOv) that features Pt-O-Ti3+ short charge separation site, which enables excellent H2 production performance (1519 μmol·g-1·h-1) while oxidizing moxifloxacin (k = 0.048 min-1), almost 43 and 98 times than that of pristine BaTiO3 (35 μmol·g-1·h-1 and k = 0.00049 min-1). The efficient charge separation path is demonstrated that the oxygen vacancies extract photoinduced charge from photocatalyst to catalytic surface, and the adjacent Ti3+ defects allow rapid migration of electrons to Pt atoms through the superexchange effect for H* adsorption and reduction, while the holes will be confined in Ti3+ defects for oxidation of moxifloxacin. Impressively, the BTPOv shows an exceptional atomic economy and potential for practical applications, a best H2 production TOF (370.4 h-1) among the recent reported dual-functional photocatalysts and exhibiting excellent H2 production activity in multiple types of wastewaters.

In Situ Growth Facilitating the Piezo-Photocatalytic Effect of Zn1-xCdxS/ZnO Nanorods for Highly Efficient H2 Production

Photocatalytic H₂ production holds promise for alleviating energy and environmental issues. The separation of photoinduced charge carriers plays vital roles in enhancing the activity of photocatalytic H₂ production. The piezoelectric effect has been proposed to be effective in facilitating the separation of charge carriers. However, the piezoelectric effect is usually restricted by the noncompact contact between the polarized materials and semiconductors. In this study, Zn_1-xCd_xS/ZnO nanorod arrays on stainless steel for piezo-photocatalytic H₂ production are fabricated by an in situ growth method, achieving an electronic-level contact between Zn_1-xCd_xS and ZnO. The separation and migration of photogenerated charge carriers in Zn_1-xCd_xS are significantly improved by the piezoelectric effect induced by ZnO under mechanical vibration. Consequently, under solar and ultrasonic irradiation, the H₂ production rate of Zn_1-xCd_xS/ZnO nanorod arrays achieves 20.96 μmol h^-1 cm^-2, which is 4 times higher than that under solar irradiation. Such a performance can be attributed to the synergies of the piezoelectric field of bent ZnO nanorods and the built-in electric field of the Zn_1-xCd_xS/ZnO heterostructure, which efficiently separate the photoinduced charge carriers. This study provides a new strategy to couple polarized materials and semiconductors for highly efficient piezo-photocatalytic H₂ production.

Intrinsically morphological effect of perovskite BaTiO3 boosting piezocatalytic uranium extraction efficiency and mechanism investigation

Developing a convenient, efficient and eco-friendly approach for the recovery of U(VI) ion is a key measure to solve the environmental problems arising from the utilization of nuclear energy. Herein, the high efficiency of uranium extraction is realized by the piezo property of perovskite BaTiO₃, revealing the intrinsically morphological engineering effect on the piezocatalytic performance. Especially, BaTiO₃ nanowires (BTO NWs) exhibit not only an excellent piezocatalytic activity with U(VI) extraction rate of 96.8% in a UO₂(NO₃)₂ aqueous solution compared to 71.3% of BaTiO₃ nanoparticles (BTO NPs), but also a promising piezocatalyst for U extraction in a real U-mining wastewater with various pH ranges. Piezo response force microscopy and finite elemental simulation show that the piezo response of BTO NWs is much higher than BTO NPs. Additionally, some factors (pH, various ions, different powers) are explored on piezocatalytic efficiency for U(VI) extraction. The results from electron spin resonance and the charge/radical capture experiments confirm that the active species (e^-, •O^2-, •OH) stemmed from the piezo induction of BTO NWs and BTO NPs in the piezocatalytic U(VI) reduction process. The present work reveals the structure-performance correlation during piezocatalysis and highlights the crucial role of piezocatalysis in dealing with environmental problems.

Enhanced plasmonic photocatalytic performance of C3N4/Cu by the introduction of a reduced graphene oxide interlayer

Cu nanoparticles (NPs) are low-cost surface plasmonic resonance (SPR) metal nanostructures, and their SPR properties can be used to enhance the photocatalytic hydrogen evolution performance of carbon nitride (C₃N₄). But their actual performance is usually limited, and one key factor is their poor interfacial quality. In this work, a highly conductive reduced graphene oxide (RGO) interlayer is introduced between protonated C₃N₄ (PCN) nanosheets and Cu NPs, which can act as an efficient sink for photogenerated electrons from C₃N₄ and hot electrons from Cu NPs, and simultaneously serve as reaction sites for the hydrogen evolution reaction, and accelerate the charge transport by the formed C-O-C and C-O-Cu bonds. The optimal hydrogen evolution rate of the optimized PCN/RGO/Cu is 1.30 mmol g^-1 h^-1, which is 6.76, 2.47 and 2.41 times that of PCN, PCN/RGO and PCN/Cu, respectively, and it can further reach up to 13.22 mmol g^-1 h^-1 by loading moderate Pt NPs. Meanwhile, the introduced RGO can effectively anchor Cu NPs to enhance the stability of the photocatalyst. In addition, due to the broad SPR response of Cu NPs, a near-infrared photocatalytic performance is realized for PCN/RGO/Cu with an apparent quantum efficiency of 0.46% at 765 nm.

Synergy of VN and Fe2O3 Enables High Performance Anodes for Asymmetric Supercapacitors

Fe₂O₃ is one of the most common anode materials beyond carbons but suffers from unsatisfactory capacity and poor stability, which are associated with the insufficient utilization of active material and the structural instability caused by the phase transformation. In this work, we report an effective strategy to overcome the above issues through electronic structure optimization by constructing delicately designed Fe₂O₃@VN core-shell structure. The Fe₂O₃@VN/CC exhibits a much higher areal capacity of 254.8 mC cm^-2 at 5 mA cm^-2 (corresponding to 318.5 mF cm^-2, or 265.4 F g^-1) than the individual VN (48 mC cm^-2, or 60 mF cm^-2) or Fe₂O₃/CC (93.36 mC cm^-2, or 116.7 mF cm^-2), along with enhanced stability. Moreover, the assembled asymmetric supercapacitor devices based on Fe₂O₃@VN/CC anode and RuO₂/CC cathode show a high stack energy density of 0.5 mWh cm^-3 at a power density of 12.28 mW cm^-3 along with good stability (80% capacitance retention after 14000 cycles at 10 mA cm^-2). This work not only establishes the Fe₂O₃@VN as a high-performance anode material but also suggests a general strategy to enhance the electrochemical performance of traditional anodes that suffer from low capacity (capacitance) and poor stability.

Axial optimization of biomimetic nanoenzyme catalysts applied to oxygen reduction reactions

Inspired by the bio-oxygen oxidation/reduction processes of hemoglobin, iron-based transition metal-like enzyme catalysts have been explored as oxygen reduction reaction (ORR) electrocatalysts. We synthesized a chlorine-coordinated monatomic iron material (FeN₄Cl-SAzyme) via a high temperature pyrolysis method as a catalyst for the ORR. The half-wave potential (E_1/2) was 0.885 V, which exceeded those of Pt/C and the other FeN₄X-SAzyme (X = F, Br, I) catalysts. Furthermore, through density functional theory (DFT) calculations, we systematically explored the better performance reason of FeN₄Cl-SAzyme. This work offers a promising approach toward high-performance single atom electrocatalysts.

Photocatalytic Applications of ReS2-Based Heterostructures

ReS2-based heterostructures, which involve the coupling of a narrow band-gap semiconductor ReS2 with other wide band-gap semiconductors, have shown promising performance in energy conversion and environmental pollution protection in recent years. This review focuses on the preparation methods, encompassing hydrothermal, chemical vapor deposition, and exfoliation techniques, as well as achievements in correlated applications of ReS2-based heterostructures, including type-I, type-II heterostructures, and Z-scheme heterostructures for hydrogen evolution, reduction of CO2, and degradation of pollutants. We believe that this review provides an overview of the most recent advances to guide further research and development of ReS2-based heterostructures for photocatalysis.