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Rational design of electrode materials for sodium-ion batteries with high flexibility is still challenging. Here, superelastic 3D few-layer MoS2/carbon framework heterogeneous electrodes (abbreviated as, MoS2@CF) are fabricated by a simple vacuum infiltration and heating process. The interconnected ultrathin MoS2network filled with carbon framework forms a 3D heterogeneous network with hierarchical pore structure. The unique structure of the electrodes results in excellent mechanical and electrochemical performances. The MoS2@CFelectrodes exhibit superior elasticity and recoverability. After 180° bending repeatedly, the electrodes still can recover their initial sizes. Moreover, the electrodes show outstanding cycling stabilities with high reversible capacities reaching up 240 mA h g−1after 500 cycles at 1 A g−1(capacity retention of ~ 99%). Full-cells assembled with MoS2@CFanodes and Na3V2(PO4)3cathodes show high reversible capacity (~ 252 mA h g−1at 0.5 A g−1). Overall, the superior mechanical properties and high electrochemical performances indicate the promising potential of MoS2@CFelectrodes in large-scale flexible sodium-ion storage devices.

With the fast development of the Internet of Things, the requirements of system miniaturization and integration have accelerated research on multifunctional sensors. Based on the triboelectric nanogenerator, a self-powered multifunctional motion sensor (MFMS) is proposed in this work, which is capable of detecting the motion parameters, including direction, speed, and acceleration of linear and rotary motions, simultaneously. The MFMS consists of a triboelectric nanogenerator (TENG) module, a magnetic regulation module, and an acrylic shell. The TENG module is formed by placing a free-standing magnetic disk (MD) on a polytetrafluorethylene (PTFE) plate with six copper electrodes. The movement of the MFMS causes the MD to slide on the PTFE plate and hence excites the electrodes to produce a voltage output. The carefully designed six copper electrodes (an inner circle electrode, an outer circle electrode, and four arc electrodes between them) can distinguish eight directions of movement with the acceleration and determine the rotational speed and direction as well. Besides, the magnetic regulation module is applied here by fixing a magnetic cylinder (MC) in the shell, right under the center of the PTFE plate. Due to the magnetic attraction applied by the MC, the MD will automatically return to the center to prepare for the next round of detection, which makes the proposed sensor much more applicable in practice.

Triboelectric nanogenerator has been considered as a potential choice for the booming Internet of Things as distributed energy supply unit. However, the widely used organic materials are restricted by weak aging/temperature resistance in severe conditions. In comparison, inorganic materials possess better aging/temperature resistance, but they have been overshadowed by their inferior charge density. To address this issue, inorganic single crystals have been used as a friction layer to improve the contact electrification effect of inorganic materials. This approach enhances the charge density to 170 μC m−2and 335 μC m−2, reaching its theoretical value in air and under vacuum, respectively. Meanwhile, a quantitative understanding of the charge transfer mechanism between single crystal and metal is established, which is strongly influenced by the work function and atom species at the interface. This work provides theoretical guidance for the contact electrification process of inorganic material, and breaks its shackle of inferior charge density, greatly expanding the triboelectric series and laying a foundation for the application of triboelectric nanogenerator in extreme environments.

Owing to the compatibility with the traditional integrated circuit technology, it is of great significance to enhance the photoresponse performance of Silicon (Si)-based photodetectors (PDs) in the near-infrared (NIR) wavelength. Here, by introducing the piezo-phototronic effect, the photoresponsivity and the specific detectivity of the p-Si/n-CdS heterojunction NIR PD are enhanced by 966 times and two orders of magnitude with a 1064nm illumination of 0.35mWcm−2power density under -0.50‰ compressive strain, which is even better than those of commercial Si PDs. The piezo-phototronic effect is a three-way coupling effect of piezoelectricity, semiconductor and optical excitation in piezoelectric semiconductors, such as wurtzite structured CdS. Alternatively, the performance enhancement of the n-Si/n-CdS heterojunction PD by the piezo-phototronic effect is much less than that of the p-n heterojunction PD under the same compressive straining conditions, due to their different energy band structures near the Si/CdS heterojunction. This work provides not only a facile solution-processed fabrication for high-performance Si-based NIR PDs, but also a deep understanding about the piezo-phototronic effect on the performance enhancement of Si/CdS heterojunction NIR PDs.

Rapid advancements in stretchable and multifunctional wearable electronics impose a challenge on corresponding power devices that they should have comparable portability and stretchability. Here, we report a highly stretchable and washable all-yarn-based self-charging knitting power textile that enables both biomechanical energy harvesting and simultaneously energy storing by hybridizing triboelectrical nanogenerator (TENG) and supercapacitor (SC) into one fabric. With the weft-knitting technique, the power textile is qualified with high elasticity, flexibility, and stretchability, which can adapt to complex mechanical deformations. The knitting TENG fabric is able to generate electric energy with a maximum instantaneous peak power density of ∼85 mW·m–2and light up at least 124 light-emitting diodes. The all-solid-state symmetrical yarn SC exhibits lightweight, good capacitance, high flexibility, and excellent mechanical and long-term stability, which is suitable for wearable energy storage devices. The assembled knitting power textile is capable of sustainably driving wearable electronics (for example, a calculator or temperature–humidity meter) with energy converted from human motions. Our work provides more opportunities for stretchable multifunctional power sources and potential applications in wearable electronics.

A nanogenerator, as a self-powered system, can operate without an external power supply for energy harvesting, signal processing, and active sensing. Here, near-infrared (NIR) photothermal triggered pyroelectric nanogenerators based on pn-junctions are demonstrated in a p-Si/n-ZnO nanowire (NW) heterostructure for self-powered NIR photosensing. The pyroelectric-polarization potential (pyro-potential) induced within wurtzite ZnO NWs couples with the built-in electric field of the pn-junction. At the moment of turning on or off the NIR illumination, external current flow is induced by the time-varying internal electric field of the pn-heterostructure, which enables a bias-free operation of the photodetectors (PDs). The NIR PD exhibits a high on/off photocurrent ratio up to 107and a fast photoresponse component with a rise time of 15 μs and a fall time of 21 μs. This work provides an unconventional strategy to achieve active NIR sensing, which may find promising applications in biological imaging, optoelectronic communications, and optothermal detections.

Although silicon (Si) devices are the backbone of modern (opto-)electronics, infrared Si-photosensing suffers from low-efficiency due to its limitation in light-absorption. Here, we demonstrate a large improvement in the performance, equivalent to a 366-fold enhancement in photoresponsivity, of a Si-based near-infrared (NIR) photodetector (PD) by introducing the piezo-phototronic effect via a deposited CdS layer. By externally applying a −0.15‰ compressive strain to the heterojunction, carrier-dynamics modulation at the local junction can be induced by the piezoelectric polarization, and the photoresponsivity and detectivity of the PD exhibit an enhancement of two orders of magnitude, with the peak values up to 19.4 A/W and 1.8 × 1012cm Hz1/2/W, respectively. The obtained maximum responsivity is considerably larger than those of commercial Si and InGaAs PDs in the NIR waveband. Meanwhile, the rise time and fall time are reduced by 84.6% and 76.1% under the external compressive strain. This work provides a cost-effective approach to achieve high-performance NIR photosensing by the piezo-phototronic effect for high-integration Si-based optoelectronic systems.

The energy crisis and environmental pollution are the two major challenges facing humanity, and harvesting energy from the ocean is a promising solution. In this paper, a triboelectric-electromagnetic-piezoelectric hybrid energy harvester (TEP-HEH) for low frequency wave energy harvesting is presented. With the introduction of the cantilever beam structure, the vibration frequency is converted from 0.2 Hz (simulated wave frequency) to 7.2 Hz, which greatly improves the energy harvesting performance of the electromagnetic generator (EMG) and the piezoelectric nanogenerator (PENG) modules. By broadening the frequency bandwidth of wave energy harvesting, a large power density of 5.73 W m−3is obtained for the TEP-HEH. Besides, the output performance of TENG, EMG, and PENG modules is investigated and the connection mode of the three types of modules is discussed. The TEP-HEH can light up a commercial lighting bulb with a rated power of 5 W or power small electronics. This work provides an efficient solution for low frequency wave energy harvesting and the realization of the blue-energy dream.

The instability and high resistance of metallic Na/solid-state electrolyte (especially oxide-based electrolyte) interface are still challenges for all-solid-state sodium batteries. Herein, we propose a grain-boundary engineering strategy to stabilize the Na/Na3Zr2Si2PO12interface and improve the capability of sodium ion transfer at the interface. The chemical composition at the grain boundary of Na3Zr2Si2PO12is mediated via the addition of sintering additive Na2B4O7to facilitate the densification sintering at relatively low temperature and boost sodium ion migration across the grain boundary. Na3Zr2Si2PO12-10wt% Na2B4O7demonstrates an optimized conductivity of 1.72 mS cm-1at room temperature and the corresponding symmetric sodium cells exhibit ultra-stable sodium plating/stripping cycling under a current density of 0.3mAcm-2for over 2500h at room temperature. Analysis reveals that a kinetically stable interphase forms between electrolyte and metallic Na, reducing the interfacial resistance from 90 ohm cm2for Na3Zr2Si2PO12to 36 ohm cm2for Na3Zr2Si2PO12-10wt% Na2B4O7. Cycling at stepwise changing temperature reconfirms the super stability of Na/Na3Zr2Si2PO12-10wt% Na2B4O7interface. All solid-state batteries based on the Na3Zr2Si2PO12-10wt% Na2B4O7demonstrates excellent cycling performance for over 200 cycles with limited capacity degradation. Our findings here open up a fertile avenue of exploration for all-solid-state sodium batteries utilizing NASICON-type electrolytes.

The introduction of a built-in electric field by using ferroelectric materials is an efficient way to modulate the carrier generation and transportation behavior of photocatalysts. Here, we propose a hydrothermal-synthesized Ag2O/BaTiO3heterostructure composite, whose photocatalytic performance can be largely enhanced by a four-way coupling effect among piezoelectricity, pyroelectricity, semiconductor and photoexcitation, referred as the piezo/pyro-phototronic synergistic effect. The photoelectrochemical (PEC) test of Ag2O/BaTiO3shows a high photocurrent density of 3.48 mA/cm2at 1.5 VSCE, which is 1.5 and 1.3 times as high as that of pristine BaTiO3and Ag2O, respectively, and the transient photocurrent density of the composite at 0.5 VSCEis 20 times higher than that of the pure BaTiO3. Under varying temperature field and ultrasonic excitation condition, the photocatalytic degradation efficiency of the Ag2O/BaTiO3composite is enhanced greatly when compared to that under only light illumination condition. This enhancement can be attributed to the attraction and release process of photogenerated carriers during the varying temperature field and ultrasonic excitation cycling. These results indicate that the ferroelectric heterostructure composites can act as a promising photocatalyst in wastewater treatment field under different environmental conditions.

Ferroelectric materials have exhibited immense promise for the control of optoelectronic processes in emerging devices. However, the utilization of ferroelectric materials to directly modulate the energy band at the junction interface has rarely been investigated. Here, a ferroelectric V-doped ZnO nanosheets/p-Si heterojunction photodetector (VZnO/Si PD) has been prepared, and the effect of ferroelectricity on the photoresponse performance of the VZnO/Si PD is studied deeply. Due to the existence of aligned ferroelectric spontaneous polarization charges under applied electrical field, the junction interface energy band can be modulated directly and effectively, which greatly improves the generation, separation and transportation efficiency of photogenerated electron-hole pairs. In contrast with the non-ferroelectric ZnO/Si PD, the VZnO/Si PD has a large enhancement in photoresponse performance with a twelve-fold increase in the photoresponsivity (R) under +1 V bias, accompanied by fast response speed in a broad spectral range. Interestingly, even under the −1 V bias voltage, the reverse ferroelectric polarizations also can improve the photoresponse behavior. These results prove the feasibility of direct modulation on energy band structure at the junction interface by ferroelectricity, which provides a new perspective for energy band engineering.

The rechargeable sodium-ion battery has become a research hotspot due to low cost and a large abundance of sodium resources. In this work, a novel nano-architecture of Cu2Se nanoparticles imbedded in ordered mesoporous carbon (Cu2Se@ CMK-3) was synthesized. Benefiting from the high conductivity and special nano-architecture of CMK-3 matrix, the as-synthesized Cu2Se@ CMK-3 composite delivers a high specific discharge capacity (231 mA h g[?]1) and superior cycling stability (a capacity decay of 0.33% per cycle during 100 cycles at 0.1 C) when used as cathode in sodium-ion batteries.

This paper investigates a system of 0.93Bi0.5Na0.5TiO3–0.06BaTiO3–0.01K0.5Na0.5NbO3–xCuO (BNT–BT–KNN–xCuO, x=0−0.04mol.%) ceramics, which were fabricated by the conventional solid-state process through the granulation of vacuum freeze drier. The results show that the CuO doping made a significant enhancement on the piezoelectric properties of the BNT–BT–KNN ceramics. With the doping of CuO, the transition temperature between ferroelectric phase and ergodic relaxor state is reduced to near room temperature, resulting in pinched P–Eloops and “sprout” shape S–Ecurves. For the composition with x=0.01, a high unipolar strain of 0.39% under 5kV/mm contributes a large d33∗∼780pm/V at room temperature, which is competitive with the other BNT-based ceramics.