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The Ni(OH)2/MoS2 NF interface offers a strain-induced piezoelectric potential that promotes adsorption and intermediates of the reactions, which results in a kinetic barrier reduction in the water-splitting process and boosts the HER and OER.

Rice husk-derived porous SiO2 is incorporated into a polyethylene oxide polymer to form a low-cost composite polymer electrolyte that is shown, using theoretical calculations and experimentally, to possess enhanced ionic conductivity.

This work reports a new approach to amending polydimethylsiloxane (PDMS) by supporting α-Fe2O3 nanoparticles (NPs), thereby generating a material suitable for use as a negative triboelectric material. Additionally, human hair exhibits a profound triboelectrification effect and is a natural regenerative substance, and it was processed into a film to be used as a positive triboelectric material. Spatial distribution of α-Fe2O3 NPs, the special surface morphologies of a negative tribological layer containing nano-clefts with controlled sizes and a valley featuring a positive tribolayer based on human hair made it possible to demonstrate facile and scalable fabrication of a triboelectric nanogenerator (TENG) presenting enhanced performance; this nanogenerator produced a mean peak-to-peak voltage of 370.8 V and a mean output power density of 247.2 μW cm−2 in the vertical contact-separation mode. This study elucidates the fundamental charge transfer mechanism governing the triboelectrification efficiency and its use in harvesting electricity for the further development of powerful TENGs suitable for integration into wearable electronics and self-charging power cells, and the work also illustrates a recycling bioeconomy featuring systematic utilization of human hair waste as a regenerative resource for nature and society.

Eco-friendly energy harvesting from the surrounding environment has been triggered extensive researching enthusiasm due to the threat of global energy crisis and environmental pollutions. By the conversion of mechanical energy that is omnipresent in our environment into electrical energy, triboelectric nanogenerator (TENG) can potentially power up small electronic devices, serves as a self-powered detectors and predominantly, it can minimize the energy crisis by credibly saving the traditional non-renewable energy. In this study, we present a novel bio-based TENG comprising PDMS/α-Fe

Water pollution is one of the leading causes of death and disease worldwide, yet mitigating it remains a challenge. This paper presents an efficient new strategy for the processing of wastewater utilizing an accessible redox reaction with MoSe2 nanoflowers, which shows a strong oxidizing ability and permits the decomposition of dye molecules in dark environments without the need for an external power source. This reaction can treat wastewater at a decomposition rate above 0.077 min−1, even when interacting with organic pollutants at concentrations up to 1500 ppm. Theoretical calculations by Dmol3 simulation elucidates that the reactions proceed spontaneously, and the kinetic constant (k obs) for this redox reaction with 10 ppm RhB dye is 0.53 min−1, which is 65 times faster than the titanium dioxide photocatalytic wastewater treatment. More importantly, the residual waste solution can be further utilized as a precursor to reconstruct the MoSe2 nanoflowers. To demonstrate the effectiveness and reusability, the treated effluent is directly used as the sole source of irrigated water for plants with no adverse effect. This method offers an eco‐friendly and more accessible way to treat industrial wastewater with zero‐discharge., In this work, an efficient new strategy is presented for the processing of wastewater utilizing an accessible redox reaction with MoSe2 nanoflowers, which shows a strong oxidizing ability and permits the decomposition of dye molecules in dark environments without the need of an external power source.

This work reports a new approach to amending polydimethylsiloxane (PDMS) by supporting α-Fe

In this work, we discover a piezoelectrocatalytic system composed of a ferroelectric heterostructure of BaTiO3 (BTO)@MoSe2 nanosheets, which exhibit piezoelectric potential (piezopotential) coupling with electrocatalyzed effects by a strain-induced piezopotential to provide an internal bias to the catalysts' surface; subsequently, the catalytic properties are substantially altered to enable the formation of activity states. The H2 production rate of BTO@MoSe2 for the piezoelectrocatalytic H2 generation is 4533 μmol h-1 g-1, which is 206% that of TiO2@MoSe2 for piezophototronic (referred to as piezophotocatalytic process) H2 generation (∼2195.6 μmol h-1 g-1). BTO@MoSe2 presents a long-term H2 production rate of 21.2 mmol g-1 within 8 h, which is the highest recorded value under piezocatalytic conditions. The theoretical and experimental results indicate that the ferroelectric BTO acts as a strain-induced electric field generator while the few-layered MoSe2 is facilitating piezocatalytic redox reactions on its active sites. This is a promising method for environmental remediation and clean energy development.

High entropy material demonstrates several effects from multi-component composition, which is potential in the catalytical field. During this decade, combining the mechanical force-driven piezoelectric/ferroelectric catalysts with photocatalysts has attracted much attention due to the separation of photogenerated carriers, leading to synergistic catalytic activities. This study reports a novel composite of high entropy oxide (CaZrYCeCr)O2 with unique ferroelectric properties mixing with bismuth titanate (Bi4Ti3O12) microplates, improving the piezo-phototronic catalytic activities. The results show that high entropy oxide catalyst (CaZrYCeCr)O2 mainly consists of the porous structure with multivalent transition metal substitution, contributing to severe lattice distortion. Consequently, the precipitation of disordered phase Ca(Zr1-xCrx)O3(x=0.05~0.1) caused by lattice distortion was decorated on the porous framework. In addition, Ca(Zr1-xCrx)O3 with a non-centrosymmetric structure exhibits ferroelectric property and plays a vital role in separating the electron-hole pairs, which performs higher degradation efficiency around 588 % compared to pristine ZrYCeO2. Additionally, the ferroelectric Bi4Ti3O12 was considered to construct a Z-scheme catalytic activity and form a heterojunction high entropy oxide. Furthermore, we demonstrated that morphotropic phase boundaries between Bi4Ti3O12 and CaZr1-xCrxO3 could dramatically enhance the ferroelectric property and promote the performance of the piezo-phototronic activities, revealing that CaZrYCeCrO2/ Bi4Ti3O12 could be an innovative catalyst in the future.

Triboelectric nanogenerators (TENGs) play a vital role in self-powered electronics, based on their superior energy harvesting ability and simple construction. In this work, polyvinyl alcohol (PVA) hydrogel is fabricated, exhibiting a three-dimensional (3D) network structure that allows PVA chains to be covered by a large amount of water. Combining MXene nanosheets with the hydrogel TENG, the composite improves the ion transport of the hydrogel and provides the streaming vibration potential (SVP) mechanism. This composite effectively enhances the output performance of hydrogel TENG. Furthermore, this work adopts different functional groups of silane (APTES, CPTMS, FOTS) to modify the surface work function of MXene nanosheets. The surface modification increases the charge density at the interface between MXene and water inside the hydrogel, improving the electrical output performance and mechanical sensitivity of MXene hydrogel TENG (MH-TENG). The result demonstrates that the electrical output performance of MH-TENGs modified by 1H,1H,2H,2H-Perfluorooctyltriethoxysilane (FOTS) is approximately two times larger (output-voltage~85 V/output-current~240 nA) than pristine hydrogel TENG (output-voltage~40 V/output-current~100 nA). The MH-TENG behaves unlimited potential in the use of flexible electronics, such as movement monitoring electronics, strength sensors on the paddle, and wearable energy harvesting devices in the future.

Single-atom catalyst as an advanced co-catalyst shows promising potential in energy fields such as water splitting, degradation of pollutants, chemical conversion field, etc. It takes advantage of increased active sites and sub-nanometer size effects with electron confinement by reducing the size of supported noble metals; furthermore, a single-atom catalyst maximizes the atomic efficiency of metals and provides a low atomic coordination number for the active center. In this work, we discovered that the isolated single atoms (SAs) stabilized by the support of g-C3N4 as named by SA-Pt/g-C3N4. Single-atom catalyst is synthesized by anchoring Pt atoms in graphitic carbon nitride (g-C3N4) with different Pt-loading [0.01wt% to 1wt% H₂PtCl₆·(H₂O)₆]. Under flexocatalytic process, the k rate constant of the SA-Pt/g-C3N4 with 0.01wt% of Pt is 3×10-3 s-1 for decomposition of dye molecules, which is 2 times the pristine g-C3N4. In addition, the flexocatalytic hydrogen evolution of SA-Pt/g-C3N4 provides H2 production, reaching nearly 125 μmolgh-1, which is 312% of the pristine g-C3N4 (~40 μmolgh-1). The working mechanism of flexocatalytic activity suggests the mechanical strain-induced flexoelectric potential (flexopotential) and proceeding with redox's electrochemical reaction. In addition, the single-atom act as a critical role in attracting electrons to accelerate the reaction process. The single-atom catalyst of 2D materials is highly potential for applying in water splitting and degradation of pollutants through the flexocatalytic process.

We demonstrate the self-powered wireless triboelectric vibration sensor as made from the naturally nanoporous SiO2 particles for allowing the detection of the vibrations and movement in the underwater environment. The nanoporous SiO2 particles are directly converted from the rice husks (referred to as RHSiO2), which exhibit strongly interacting surface hydroxyl groups. Through the enzymatic treatments, the surface potential of the RHSiO2 particles can be modulated to obtain either an extremely low or strongly high electronegativity. Specifically, by adding fluorinated groups using fluoroalkylsilane (FOTS) treatment to obtain RHSiO2-F, the charge density of the RHSiO2-F triboelectric nanogenerator (TENG) can be enhanced ∼ 56.67-fold as compared to the untreated RHSiO2-TENG. The power density of the RHSiO2-F TENG is increased from 0.077 mWm−2 to 261 mWm−2. The RHSiO2-F particles are encapsulated in a quartz cube to fabricate a self-powered wireless sensor that can be stabilized for operating in an underwater environment at various temperatures. The theoretical calculation further demonstrates that the triboelectric potential is dramatically established between the surface functionalized RHSiO2-F particles and the quartz's surface. With porous nature of rice husks covered with nano-Si is of a high functionality for designing a new-type TENG which has a great potential to apply in the environmental monitoring.

Transition-metal dichalcogenides (TMDs), a two-dimensional (2D) nanostructured material, has, to a greater extent, technological applications in catalysis, sensors, lithium-ion batteries, and optoelectronic devices due to their unique structure and electrical properties. Recently, the 2D TMD tungsten disulfide (WS2) has been regarded as one of the most promising anode candidates for lithium-ion batteries. However, the exploration of the WS2 sheets with the 1T metallic phase still remains a prodigious challenge to improve its conductivity and cycling stability in the application of lithium-ion batteries. In this work, the highly rich 1T few-layered WS2 nanoflowers (referred to as rich 1T WS2 NFs) were synthesized, exhibiting a rich 1T metallic phase with few-layered structures around the active edge sites of the NFs for achieving a fast electron/ion transfer, thereby delivering the enhanced cycling performance and lithium storage. The rich 1T WS2 NFs exhibits an irreversible capacity (charge capacity) of 8...

Clean water is essential in our daily life. However, nearly one billion people are forced to drink water contaminated with bacteria, leading to diarrhea, dehydration, and even death. Previously, various photocatalysts have been applied to replace high-cost and highly toxic methods for sewage treatment. Nevertheless, the requirement of external light sources limits their application. Herein, we develop a new type of nanocatalyst based on single- and few-layered molybdenum disulfide (MoS2) nanosheets (NSs) that can catalyze the generation of reactive oxygen species (ROS) to inactivate bacteria either through a piezoelectric effect (mechanical vibration) or photocatalytic effect (light irradiation). After 60 min of mechanical vibration or visible-light irradiation, the MoS2 NSs can reduce Escherichia coli (E. Coli) by 99.999%. In addition, the ROS generation efficiency and bacterial disinfection performance of the catalyst can be enhanced by depositing Au nanoparticles (NPs) on MoS2 NSs. The period of mechanical vibration or visible-light irradiation that achieves the same 99.999% reduction in E. coli is shortened to 45 min. Moreover, a hybridization of the piezoelectric and photocatalytic effects results in a performance superior to that obtained with the individual effects. A 99.999% reduction in E. coli is also accomplished within 15 min through a combination of mechanical vibration and near-infrared (NIR)-light irradiation. This MoS2 nanocatalyst is a promising candidate for nextgeneration water purification systems because of its ability to be triggered by diverse environmental stimuli.

The BiFeO3/TiO2 core-shell nanocomposites with the R3C space group is demonstrated to exhibit the superior synergistically catalyst activities, which is a combination of the piezo- and photo-catalytic activities (referred to as the piezophototronic effect). With the application of an ultrasonification and light irradiation, the degradation activity for the decomposition of the dye molecules by the piezoelectric polarization of the BiFeO3/TiO2 core-shell nanocomposites (referred to as the hybrid catalyst, BiFeO3/TiO2 NCs-P) is 432% higher than that of the un-poling BiFeO3/TiO2 nanocomposites (BiFeO3/TiO2 NCs). In responding to the excitation of the mechanical force (ultrasonic vibration), the results demonstrate that the BiFeO3 nanoparticles can effectively reduce the recombination rate of the carriers by the built-in electric field. Subsequently, the redox reaction has taken place on the surface of the hybrid catalyst in the solution to generate the powerful oxidizing radicals and further dissociate the organic dyes. The reaction k constant of the piezophototronic effect is 566% and 388% higher than that of the sole piezocatalytic and the photocatalytic process, respectively. After four consecutive cycling degradation tests, the hybrid catalyst still reaches ~85% of the degradation activity by the piezophototronic effect. Based on the fluorescence luminescence (FL) analysis, the signals associated to the hydroxyl radicals elevate with the increase of the catalysts’ concentration and the ultrasonic vibration time. This work reveals that the hybrid catalysts contains the ferroelectric material, which provides a new catalyst design strategy in the industrial application.

Two-dimensional (2D) structures have received substantial attention in the energy applications. However, a common problem with 2D layered structures is restacking during the charge–discharge process. In this work, a graphene-like structure, molybdenum disulfide (S-MoS2), was synthesized using the hydrothermal method. Moreover, zero-dimensional (0D) α-Fe2O3 nanoparticles were constructed to act as a spacer in the slurry. Subsequently, the three-dimensional (3D) S-MoS2@Fe2O3 nanoparticles were fabricated by the ultrasonic vibration process to improve their electrochemical properties. On the basis of the 3D architecture, the α-Fe2O3 nanoparticles not only prevent the restacking of MoS2 sheets, but also increase accessibility for electrolyte penetration to provide more active sites and lower the diffusion energy barrier for Li+ ions during the charge–discharge process. In the potential window of 3 V–0.01 V, high-rate charge–discharge and long cycle tests were performed to investigate the electrochemical performance of all electrodes. The electrochemical performance was enhanced through spatial distribution of MoS2. In summary, these S-MoS2@Fe2O3 nanoparticles possess high potential for application as anode materials in next-generation lithium-ion batteries.

Single crystal wafers, such as silicon, are the fundamental carriers of advanced electronic devices. However, these wafers exhibit rigidity without mechanical flexibility, limiting their applications in flexible electronics. Here, we propose a new approach to fabricate 1.5 in. flexible functional zinc oxide (ZnO) single crystal wafers with high electron mobility (>100 cm2 V-1 s-1) and optical transparency (>80%) by a combination of thin-film deposition, a chemical solution method, and surficial treatment. The uniformity of the flexible single crystal wafers is examined by an advanced scanning X-ray diffraction technique and photoluminescence spectroscopy. The transport properties of ZnO flexible single crystal wafers retain their pristine states under various bending conditions, including cyclability and endurability. This approach demonstrates a breakthrough in the fabrication of the flexible single crystal wafers for future flexible optoelectronic applications.

With exciting functionality, topological defects in ferroic system have attracted much attention. Under proper design, the emergence of polar domain walls in non-polar ferroelastics enables piezo-phototronic effect. In this study, we revealed ferroelastic twin texture with localized piezoelectric effect in epitaxial BiVO4 film by piezoresponse force microscopy. Supported by the strain field analysis, we found the piezoresponse confined at domain wall area is attributed to the flexoelectric effect induced by the presence of ferroelastic twin domains during the paraelastic to ferroelastic phase transition. The piezo-phototronic phenomenon was further supported the experimental evidence of dye-degradation and generation of reactive radicals. This work not only provides new insights into the introduction of piezo-phototronic effects in non-polar materials, but also sheds light on a new concept to use material inhomogeneity for acquiring multifunctionality.

Intense light attenuation in water/wastewater results in photocatalysts exhibiting a low quantum efficiency. This study develops a novel piezoelectrocatalysis system, which involves quartz microrods (MRs) abundantly decorated with active-edge-site MoS

A self-powered photoelectrochemical microsystem comprising quartz prism microrods assembled with TiO2 nanoparticles (NPs; quartz/TiO2) is developed and demonstrates a marked catalytic effect on organic dye degradation and hydrogen evolution through a piezopotential sensitized photocatalytic process (referred to as synergistically piezophotocatalytic processes or piezophototronics herein). The results of piezoresponse force microscopy (PFM) and the electrical output of the piezoelectric nanogenerator suggest that the quartz microrods act as a self-powered bias subjected to mechanical stress that can produce an additional electric field around the surrounding TiO2 NPs. With the finite element method, the simulation results indicate that the interfacial stress effect between the two materials plays a vital role in enhancing piezoelectric potential (piezopotential). The reaction rate constant (kobs) for the dye degradation of the quartz/TiO2 heterostructure reaches 0.0624 min−1 under a piezophototronic effect, approximately 2.2 times greater than that for photocatalysis (rate constant kobs = 0.0281 min−1). Additionally, hydrogen production reaches 438.48 µmol·g−1·h−1 through the synergistic piezophototronic effect, a 225% increase when compared with that of pristine quartz. This improvement is attributable to mechanical force–induced piezoelectric polarization, which acts as an internal bias modulating the TiO2 band structure and ejecting the photogenerated electrons and holes in opposite directions, thereby retarding recombination behaviors and facilitating redox reactions.

In the era of Internet of Things, the demand for flexible and transparent electronic devices has shifted to the forefront of materials science research. However, the radiation damage to key performance of transparent devices under radiative environment remains as a critical issue. Here, we present a promising technology for nonvolatile transparent electronic devices based on flexible oxide heteroepitaxy. A direct fabrication of epitaxial lead lanthanum zirconate titanate on transparent flexible mica substrate with indium tin oxide electrodes is presented. The transparent flexible ferroelectric heterostructures not only retain their superior performance, thermal stability, reliability, and mechanical durability, but also exhibit remarkably robust properties against to a strong radiation exposure. Our study demonstrates an extraordinary concept to realize transparent flexible nonvolatile electronic devices for the design and development of next-generation smart devices with potential application in electronics, automotive, aerospace, and nuclear systems.

We have demonstrated that the hydroxyl radicals (OH•) and hydrogen gas can be generated by the application of mechanical force to the active edge sites of the MoS2 nanoflowers in a dark environment. The non-centrosymmetric structure of the single- and few-layered MoS2 nanoflowers were uniformly dispensed in the aqueous solution. A mechanical force was applied to the aqueous solution, and the hydroxyl radicals were generated from the MoS2 nanoflowers because a piezoelectric spontaneous polarization was created around the single- and odd number of layers. To exclude the dye adsorption effect during the decomposition process, the MoS2 nanoflowers with 99.9 wt% were removed from the solution by the centrifuged process to obtain the solution without the nanoflowers. Interestingly, the solution can decompose the organic dye (i.e. Rhodamine B) instantly (see the video recording in the Supporting Information ). Based on the fluorescence (FL) spectra, the solution contained with the highly oxidized free radicals, which was strongly dependent on the concentration of the MoS2 nanoflowers in the aqueous solution. The formation of the M- ( V Mo ′ ′ ′ ′ ) and S-vacancies ( V S • • ) sites on the single-layer MoS2 acted as the F-center defects, leading to the hydroxyl radicals being accommodated on the sites to decompose the organic dye molecules and prolong the radical's lifetime up to 6 h. More importantly, with applying the ultrasonic vibration to the MoS2 nanoflowers in the deionized water and ethanol solution, a remarkable hydrogen peak was observed by the gas chromatography mass spectrometry. Moreover, as increasing the concentration of the MoS2 nanoflowers in the solution, the intensity of the hydrogen generation was increased. This is the first work to demonstrate that the dye molecule can be instantly decomposed by the free radicals solution and produced the hydrogen gas using the piezoelectricity of the MoS2 nanoflowers with the application of mechanical force in a dark environment.

This work, we achieved the first-ever demonstration in the polydimethylsiloxane embedded with the abundant single-layer tungsten disulfide (WS2) nanoflowers (PDMS/WS2 NFs) for the degradation of organic dye (Rhodamine B, RB) in dark environment. The degradation ratio of the PDMS/WS2 NFs brick reached ~ 99% and achieved ten cycling test where each cycle took 90 min for the decomposition of the dye molecules. The rate constant of the PDMS embedded WS2 NFs was 0.13 (ppms−1), with the highest degradation rate of ~ 6624 ppm L mole −1 s−1. This is the fastest degradation rate using the PDMS embedded with the abundant single-layer WS2 NFs. We further demonstrated the antibacterial properties of single and few-layers WS2 NFs reaches more than 99.99% to against the Escherichia coli (E. coli) under ultrasonic condition. The piezoresponse force microscopy (PFM) and tunneling atomic force microscopy (TUNA) unveil the dramatically piezopotential of the WS2 NFs. The piezopotential was created around the WS2 NFs to generate the reactive oxygen species (ROS) in the water mediator. The electron paramagnetic resonance (EPR) spectra further evidenced that the generation of reactive oxygen species. O2- and hydroxyl ( OH ∙ ) radicals under the mechanical strain, were responsible for decomposing the Rh-B dye molecules and the E. coli bacteria in the dark. The PDMS/MoS2 NFs brick was highly repeatable for efficient decomposition of the organic dyes, which further evidenced that by utilizing piezo-catalytic technologies in the absence of light could be an effective solution for converting mechanical energy into usable chemical energy for the degradation of pollutants.

We have demonstrated a flexible force-controlled contact electrification field-effect transistor (CE-FET). The pn CE-FET was fabricated on a flexible PET (polyethylene terephthalate) substrate using the p-type poly(3-hexylthiophene) (P3HT), and the n-type phenyl-C61-butyric acid methyl ester (PCBM) films as a conductive channel in the CE-FET. The PEO polyethylene oxide (–CH 2 CH 2 O–, PEO) was then deposited on the surface of the conductive channel to act as a contact layer. When the mobile electrode was progressively touched with the PEO contact layer, a triboelectric potential was significantly created between them. This potential can self-generate a gate signal to modulate the charge carrier transport in the conductive channel of the CE-FET and thereby provide a prospective control of its output current. The PTFE (polytetrafluoroethylene, PTFE) and the porous SiO 2 film (made from the recycling rice husks) was used as a mobile electrode in the enhancement mode and the depletion mode of the CE-FET, respectively, in order to build in an inner electric field by the triboelectric potential between the contact layer and the mobile electrode. Through controlling the distance between the two frictional layers, the output current of the pn CE-FET can be dramatically modulated from 2.84 nA to 62.31 nA in the enhancement mode, while that of the current can be controlled from 17.26 nA to 2.84 nA in the depletion mode. The pn CE-FET has provided high perspectives and opportunities for the flexible electronic devices applications in future.

The continuous quest to enhance the output performance of triboelectric nanogenerators (TENGs) based on the surface charge density of the tribolayer has motivated researchers to harvest mechanical energy efficiently. Most of the previous work focused on the enhancement of negative triboelectric charges. The enhancement of charge density over positive tribolayer has been less investigated. In this work, we developed a layer-by-layer assembled multilayer graphene-based TENG to enhance the charge density by creatively introducing a charge trapping layer (CTL) Al2O3 in between the positive triboelectric layer and conducting electrode to construct an attractive flexible TENG. Based on the experimental results, the optimized three layers of graphene TENG (3L-Gr-TENG) with CTL showed a 30-fold enhancement in output power compared to its counterpart, 3L-Gr-TENG without CTL. This remarkably enhanced performance can be ascribed to the synergistic effect between the optimized graphene layers with high dielectric CTL. Moreover, the device exhibited outstanding stability after continuous operation of &gt, 2000 cycles. Additionally, the device was capable of powering 20 green LEDs and sufficient to power an electronic timer with rectifying circuits. This research provides a new insight to improve the charge density of Gr-TENGs as energy harvesters for next-generation flexible electronics.

The hydrogen evolution rate of Au nanoparticles encapsulated by MoS2 nanoflowers (Au@MoS2 NFs) was dramatically increased through localized surface plasmon resonance (LSPR) coupling with the piezophototronic effect. The heterostructured Au@MoS2 NFs had highly active reaction sites for intense piezoelectric polarization that established an electric field and a surface plasmon effect to play a crucial role in regulating interfacial charge migration. Simultaneous light irradiation and mechanical vibration applied to the Au@MoS2 NFs increased the hydrogen evolution from 2981 μmol g−1 h−1 for the solely piezocatalytic process to 4808 μmol g−1 h−1. The hydrogen evolution rate of the Au@MoS2 NFs was 161% that of pristine MoS2 NFs. The considerable performance improvement was attributed to piezoelectric generation of hot electrons through LSPR. Density functional theory and the finite element method were employed to simulate the charge transfer of the Au@MoS2 NFs under simultaneous light irradiation and mechanical vibration. Greater mechanical strain on the heterostructured catalysts yielded a greater electric field, demonstrating the piezophototronic effect had strong synergy with LSPR and thus increasing the hydrogen evolution rate.

We have demonstrated an ultrahigh degradation activity of the single-layer and few-layered MoSe2 nanoflowers for decomposing the Rhodamine (RhB) dye by the piezo-catalyst effect. The MoSe2 nanoflowers can successfully decompose the RhB dye by 90% in 30 s through the application of the mechanical force (e.g., ultrasonic vibration) in dark. The size of the MoSe2 nanoflowers has a diameter of less than 3 µm, which exhibits a great number of the single- and few-layers with a plentiful amount of active surface sites. The interlayer spacing between each single-layer MoSe2 is ~ 0.67 nm. The piezoresponse force microscopy (PFM), and the tunneling atomic force microscopy (TUNA), further evidence that the MoSe2 nanoflowers exhibit a significantly piezoelectric potential as created by the internal electric fields in different polarization domains of the single- and few-layered MoSe2. The observed kobs rate constant is 0.3 (ppm s−1) with an ultra-fast degradation rate of ~ 69,889 ppm L mole−1 s−1. This is the fastest degradation rate in the dark among all reported catalysts. A redox process of the MoSe2 nanoflowers as induced by mechanical force in dark have been evidenced by XPS spectra. The electron paramagnetic resonance (EPR) spin trapping with 5,5-dimethylpyrroline-1-oxide (DMPO) spectra indeed demonstrated the formation of the hydroxyl radical from the MoSe2 nanoflowers during the ultrasonic vibration in dark, which is the major reactive oxygen species (ROS) for destroying the dye molecules. This is first work to demonstrate the very efficient catalyst and redox processes by piezo-catalyst effect using the MoSe2 nanoflowers.

Over the past decades, water pollution has been suggested as the leading factor to infectious diseases. There has been a worldwide concern to use photocatalysts to degrade organic pollutants in waste water. However, the requirement of light assistance in degradation process has limited the application of photocatalysts. In this paper, MoS2/PDMS nanocomposite was fabricated in order to overcome this problem. The results showed that MoS2/PDMS nanocomposite can provide a high degradation activity to purify the waste water without light assistance. The MoS2/PDMS nanocomposite preserved an activity of 67% toward dye Rhodamine B degradation even in the fourth cycling test. We found that the high degradation activity of MoS2/PDMS nanocomposite was based on the piezo-catalytic effect of single- and few-layers MoS2 nanoflowers in the nanocomposite. We also demonstrated that MoS2/PDMS nanocomposite was a useful material in the fabrication of nanogenerator to harvest waste water energy. Through the direct coating of MoS2/PDMS nanocomposite on a metal grid, electric outputs of 23 V and 13 mA/m2 can be generated when a water flow (20 mL/s) was passing the nanogenerator. In addition, when coating MoS2/PDMS nanocomposite on a flat electrode and placing it inside a water pipe, the nanogenerator could not only act as the source of electric output, but also as a self-powered sensor to locate the water passage route and/or the contamination areas in the waste water.

Multi-walled carbon-nanotube (MWCNT)-decorated WTe2 nanostars (WTe2@CNT nanocomposites) are to be employed for the first time as anode candidates in the development of lithium-ion (Li-ion) batteries. WTe2@CNT nanocomposites deliver a high discharge capacity of 1097, 475, 439, 408, 395 and 381 mA h g-1 with an increasing current density of 100, 200, 400, 600, 800 and 1000 mA g-1, respectively, while WTe2 nanostars exhibit a reversible capacity of 655, 402, 400, 362, 290 and 197 mA h g-1 with the aforementioned current densities. Furthermore, WTe2@CNT nanocomposites exhibit a superior reversible capacity of 592 mA h g-1 at 500 mA g-1 with a capacity retention of 100% achieved over 500 cycles, while bare WTe2 nanostars deliver ∼85 mA h g-1 over 350 cycles. This remarkable Li cycling performance is attributed to MWCNTs interconnected with WTe2 nanostars. In addition, the exposed active interlayers of the WTe2 nanostars, which are responsible for maintaining the structural integrity of the electrodes, buffer the large volume expansion within the WTe2 nanostars, avoiding the agglomeration of the particles. The layered WTe2 nanostars were synthesized via the solution-phase method, and present extremely good possibilities for the scaling-up of Li-ion battery storage systems.

The synthesis of LiNbO

Piezocatalyst is one of the most innovative catalysts for hydrogen evolution reaction in these years. It has attracted broad interest due to its ultra-high efficiency and renewability. In this study, we initiatively fabricate single-crystal quartz microrods (Quartz MRs) from rice husks, which possess excellent piezoelectricity. Firstly, the raw rice husks are washed and acidized with HCl solution for several hours, following by calcination at 550℃ for 6 hours to produce highly porous SiO2 (RH-SiO2) that serves as the precursor of quartz MRs. After that, some NaCl and 0.6M NaOH solution are mixed with the as-synthesized RH-SiO2. The final mixture is then poured into the Teflon-lined stainless-steel autoclave, undergoing hydrothermal process at 220℃ for 12 hours. To form the Quartz@WO3 heterostructure, Na2WO4·2H2O and citric acid are dissolved in DI water and the pH value is adjusted to 1.0 under stirring. After the solution is formed, the as-prepared quartz MRs are added into it and sealed in an autoclave, placing in the oven at 120℃ for 3 hours. Finally, the product is calcined to remove residual water and we can obtain the Quartz@WO3 heterostructure. The crystal structures of Quartz MRs and WO3 are well identified by XRD analysis, which corresponds to alpha quartz and monoclinic WO3 respectively. Though gas chromatography (GC) analysis, the hydrogen generation rate of Quartz@WO3 effectively enhances around 53% compared to that of pristine WO3 under ultrasonication as an external mechanical force, this may be associated with the piezoelectric effect from the quartz MRs.

This work, Au nanoparticles@MoS2 nanoflowers (Au NPs@MoS2 NFs) heterostructure sonicated with visible light has been confirmed it can enhance piezo-photo catalytic activity for hydrogen evolution reaction. MoS2 displays prominent photocatalytic properties due to its narrow bandgap and obsesses unique piezoelectricity at its edge sites. However, the high rate of electrons and holes recombination and lack of active sites limit efficiency for hydrogen evolution. Herein introduction of Au NPs into MoS2 NFs has been synthesized by a facile hydrothermal process and forms heterojunction structure. The transmission electron microscopy (TEM) images evidence the as-synthesized Au@MoS2 heterostructure exhibits a high surface to volume with abundant nanopetals. As compared to Au NPs decorated MoS2, utilizing Au NPs burying beneath MoS2 NFs eliminates the shielding effect of MoS2 active edge sites. Based on the cathodoluminescence (CL) spectrum, Au@MoS2 achieved to reduce the recombination possibility of electrons and holes. Through gas chromatography (GC) analysis, the hydrogen evolution of 40 nm Au@MoS2 shows over 150% better than pristine MoS2. The significant improvement arises from piezoelectricity inducing hot electron of surface plasmon resonance (SPR) effect as observed by the absorption spectrum of ultraviolet-visible (UV-Vis) spectrophotometer. The COMSOL software was employed to simulate the electric field with strain on MoS2. The mechanism on SPR-enhanced piezo-photo catalytic hydrogen evolution will be investigated.

In this work, non-stoichiometric bismuth ferrites (Bi25FeO40) particles that possess ferroelectric and photocatalysis properties were synthesized by the hydrothermal method. According to our previous work, piezoelectric materials can be employed in numerous applications. When applied to organic dye degradation, the photocatalysis effect is largely enhanced with the assistance of ferroelectricity[1, 2]. The Bi25FeO40 belongs to the I23 space group, which is a non-centrosymmetric piezoelectric crystal structure. The piezoelectricity is investigated by utilizing the piezoresponse force microscope (PFM) to measure its bias to phase relation. The lifetime of electron-hole pairs stimulated by laser could be measured by photoluminescence (PL) and time-resolved photoluminescence (TRPL). Due to its ferroelectricity, when the poling electric field raised, the remnant polarization and lifetime were increased; the intensity of the PL spectrum dropped reversely[2, 3]. This represents the recombination possibility of the electron-hole pairs were decreased by the poling process. Moreover, by adjusting the pH value of the degradation environment, the contact ability of the dye molecules and catalysts was improved. Under the condition of pH=3.5, the Rhodamine B (RhB) dye can be fully degraded in one hour while there is only 16% degraded in one hour of the original RhB solution(pH=4.8). This work demonstrated a photocatalyst assisted by ferroelectric property which could be enhanced through the poling process and prolong the lifetime of the electron-hole pairs. Furthermore, it shows greater degradation ability on RhB dye in acidic environment due to the better contact ability with the dye molecules, which makes it a new choice of acidic industrial wastewater treatment. References: Wu, M.-H., et al., Ultrahigh efficient degradation activity of single- and few-layered MoSe2 nanoflowers in dark by piezo-catalyst effect. Nano Energy, 2017. 40: p. 369-375. Wang, Y.-C. and J.M. Wu, Effect of Controlled Oxygen Vacancy on H2-Production through the Piezocatalysis and Piezophototronics of Ferroelectric R3C ZnSnO3 Nanowires. Advanced Functional Materials, 2020. 30(5): p. 1907619. Liu, Y.L. and J.M. Wu, Synergistically catalytic activities of BiFeO3/TiO2 core-shell nanocomposites for degradation of organic dye molecule through piezophototronic effect. Nano Energy, 2019. 56: p. 74-81.

Quasi-High Entropy Oxide is composed of Ca, Zr, Y, Ce, and Cr, which are synthesized via sol-gel method at room temperature. These metallic nitrates, including calcium nitrate, zirconium nitrate, yttrium nitrate, cerium nitrate, and chromium nitrate are mixed together to prepare the precursor and stirring for one four. After thoroughly mixing, adding citric acid as a chelating agent to link all kinds of metal ions together as chelates. Then, adjusting the pH value to 7 by adding ammonia solution, and drying at 90oC for 48-hour. After that, the as-synthesized dried powders were annealed at 1100oC for three-hour to obtain the final product. The x-ray diffraction pattern indicates that as-synthesized powders of CaZrYCeCrOxdemonstrated a single-phase fluorite structure with precipitating the second phase of CaZrO3, which exhibited luminescence and ferroelectric properties. Notably, based on the transmission electron microscope images, the as-synthesized CaZrYCeCrO nanoparticles display highly porous morphologies, implying that the CaZrYCeCrO may highly potential for the application of the electrochemical reactions.

Single- and few-layer MoS2 nanoflowers are first discovered to have a piezo-catalyst effect, exhibiting an ultra-high degradation activity in the dark by introducing external mechanical strains. The degradation ratio of the Rhodamine-B dye solution reaches 93% within 60 s under ultrasonic-wave assistance in the dark.

A contact electrification field-effect transistor (CE-FET) is first made from poly(ethylene oxide)/InSb/PET(polyethylene terephthalate) on the flexible force-pad application. The CE-FET operates on a unique principle that relies on the triboelectric potential difference that is established between the two tribo-surfaces, to induce an inner electrical signal by utilizing the external frictional force. Such a signal is able to modulate the carrier transport characteristics in the FET and is self-generated to have the same effect as applying a gate signal. The traditional gate electrode in the FET is replaced by an individually mobile aluminum and a polytetrafluoroethene (PTFE) electrode to serve as a positive and negative gate voltage, respectively. The n-type rich indium (In) InSb thin film is then used as a conduction channel in the CE-FET. When the PTFE film acted as a mobile gate electrode to progressively contact the PEO surface, the drain current was increased from 6 to 12 μ A by increasing the distance (d) between the PEO and the PTFE surfaces in the range from 0 to 80 μ m . In contrast, when the Al film was used as a mobile electrode to gradually contact the PEO surface, the corresponding drain current decreases from 7 μ A to 1.5 μ A , while increasing the corresponding distance from 0 to 80 μ m , respectively. Thus, the characteristic of the CE-FET has established an enhancement and depletion mode in the InSb conduction channel when the mobile electrodes of the PTFE and aluminum films were mechanically attached to the PEO surface, respectively. The CE-FET InSb is highly reliable and sensitive, which thereby opens up a new research field on the applications of the force pads.

In recent years, the use of triboelectric nanogenerators (TENGs) has become an effective technique to harvest mechanical energy based on contact electrification and the electrostatic effect. However, the electric output of TENGs decreases in environments with high relative humidity (RH), which restricts their application. The reason for this phenomenon is that charge transfer in most TENGs occurs through an electron pathway. By using gelatin/glycerol and polytetrafluoroethylene (PTFE) as triboelectric layers to construct a biocompatible TENG, we found that the electric output of the TENG can be maintained or is even enhanced at higher RH. The hydration of amino groups in gelatin resulted in additional charges (mobile ions) on the triboelectric layers during the contact electrification process, consequently increasing the electric output of the TENG. The electric output generated from the TENG increased 2-fold when the RH was increased from 20% to 60%. By using genipin to react with the amino groups in gelatin, the formation of mobile ions was blocked and the measured charge density on the triboelectric layers decreased as the RH gradually increased. We also demonstrated that the change of electric output generated from the TENG could be applied as a tool to detect RH, exhibiting the superior stability and durability of the TENG. This study also leads to a fundamental understanding of the mechanism of contact electrification when using protein as the triboelectric layer.

Highly efficient carbon-based 1D light-emitting devices require multi-quantum well heterostructures with sensitive optical properties. However, carbon nanotubes (CNTs)-based composites become much worse than expected and most of their applications such as field emission are thwarted because dispersing CNTs among one another is difficult. We demonstrate that such sensitive optical and limited field emission properties can be attained and improved, respectively, through the use of ZnO nanocrystal selective quantum well heterostructures grown on carbon nanotubes to fabricate carbon-zinc-oxide (CZO) nanotubes. ZnO can be effectively and uniformly decorated on the carbon nanotubes intramolecular junctions with abundant functional groups and also with large surface adsorption area produced by CNTs surface plasma pre-treatments at room temperature. The cathodoluminescence (CL) spectrum of the CZO nanotubes exhibits a weak UV emission peak and two distinct strong green emission peaks at 2.51 eV and at 2.4 eV, attributed to zinc-rich ZnO band-to-donor transitions and oxygen-rich ZnO band-to-acceptor transitions, respectively. Furthermore, the CZO nanotubes reach an extremely low turn-on field of 0.1 V μm−1, low threshold field of 3.1 V μm−1, but high field enhancement factor β of 110 × 103. The field emission properties are dramatically enhanced by ZnO quantum dots decorated on the carbon nanotube intramolecular junctions, which not only provide extra electron emission paths and higher carrier concentrations, but also protect the emitter from ion bombardment during operation.

Surface treatment and bonding oxygen species represent a practical method for strongly enhancing the ballistic characteristic of carbon nanotubes (CNTs) because the electrical properties strongly depend on the surface states. In this work, oxygen plasma was introduced onto the CNTs to remove the remaining defects, leading to a 44.8% improvement in the graphite-like sp2 bonding, which represents the graphite level of the CNTs. Moreover, oxygen species were bonded onto each individual CNT, as seen from the AES analysis. The conductive characteristics, such as resistivity, electron concentration, and electron mobility, for individual treated CNTs were optimized significantly under 20 s oxygen plasma treatment, giving values of 1.23 × 102 μΩ cm, 6.36 × 1018 cm−3, and 8002.23 cm2 V−1 s−1, respectively. Furthermore, we demonstrated an experimental approach to grow aligned CNTs by substrate clamping configurations without a bias voltage or porous substrate, which simplifies the complexity of procedure preparation and enhances the opportunity for extracting individually treated CNTs to investigate their specific conductive characteristics.

This work, we are the first to discover the high-output current density of the triboelectric nanogenerator (TENG) using rice husks as a source material. The raw rice husks (RH) can be directly phase transited into the amorphous SiO 2 (RH SiO2 ) structure with highly nanoporous fragments by the thermal annealing with additional acid hydrolysis process. The RH SiO2 -TENG׳s configuration is designed by polytetrafluoroethene (PTFE) and RH SiO2 films, which are chemically and thermally more stable than the metallic film. The pore size around 20–40 nm is widely distributed throughout the SiO 2 fragments that possess rich Si–O–Si and OH stretching bonds with strong tendency of repulsing electron because the H atoms have an extremely low electron affinity, leading to the RH SiO2 film exhibits much lower electron affinity when compared with the commercial SiO 2 nanoparticles. As a consequence, the area power density of the RH SiO 2 triboelectric nanogenerator (RH SiO2 -TENG) reaches 0.84 W m −2 with a peak short-circuit current density of 5.7 mA m −2 . Such a short-circuit current density is almost among the highest reported value based on dielectric-to-dielectric mode triboelectric nanogenerators. Rice husk possess many advantageous traits such as their light weight, low cost, being environmentally friendly, high porosity, excellent robustness, exceptionally chemical and thermal stability for superior corrosion resistance, makes it a valuable material for industrial applications.