Voltage‐Controlled On/Off Switching of Ferromagnetism in Manganite Supercapacitors

The ever‐growing technological demand for more advanced microelectronic and spintronic devices keeps catalyzing the idea of controlling magnetism with an electric field. Although voltage‐driven on/off switching of magnetization is already established in some magnetoelectric (ME) systems, often the coupling between magnetic and electric order parameters lacks an adequate reversibility, energy efficiency, working temperature, or switching speed. Here, the ME performance of a manganite supercapacitor composed of a ferromagnetic, spin‐polarized ultrathin film of La_0.74Sr_0.26MnO₃ (LSMO) electrically charged with an ionic liquid electrolyte is investigated. Fully reversible, rapid, on/off switching of ferromagnetism in LSMO is demonstrated in combination with a shift in Curie temperature of up to 26 K and a giant ME coupling coefficient of ≈226 Oe V⁻¹. The application of voltages of only ≈2 V results in ultralow energy consumptions of about 90 µJ cm⁻². This work provides a step forward toward low‐power, high‐endurance electrical switching of magnetism for the development of high‐performance ME spintronics.     

Superior Energy Storage Capability and Stability in Lead-Free Relaxors for Dielectric Capacitors Utilizing Nanoscale Polarization Heterogeneous Regions

The development of high-performance lead-free dielectric ceramic capacitors is essential in the field of advanced electronics and electrical power systems. A huge challenge, however, is how to simultaneously realize large recoverable energy density (W_rec), ultrahigh efficiency (η), and satisfactory temperature stability to effectuate next-generation high/pulsed power capacitors applications. Here, a strategy of utilizing nanoscale polarization heterogeneous regions is demonstrated for high-performance dielectric capacitors, showing comprehensive properties of large W_rec (≈6.39 J cm⁻³) and ultrahigh η (≈94.4%) at 700 kV cm⁻¹ accompanied by excellent thermal endurance (20–160 °C), frequency stability (5–200 Hz), cycling reliability (1–105 cycles) at 500 kV cm⁻¹, and superior charging-discharging performance (discharge rate t_0.9 ≈ 28.4 ns, power density PD ≈161.3 MW cm⁻³). The observations reveal that constructing the polarization heterogeneous regions in a linear dielectric to form novel relaxor ferroelectrics produces favorable microstructural characters, including extremely small polar nanoregions with high dynamics and multiphase coexistence and stable local structure symmetry, which enables large breakdown strength and ultralow polarization switching hysteresis, hence synergistically contributing to high-efficient capacitive energy storage. This study thus opens up a novel strategy to design lead-free dielectrics with comprehensive high-efficient energy storage performance for advanced pulsed power capacitors applications.     

Low-Iridium-Content IrNiTa Metallic Glass Films as Intrinsically Active Catalysts for Hydrogen Evolution Reaction

Although various catalytic materials have emerged for hydrogen evolution reaction (HER), it remains crucial to develop intrinsically effective catalysts with minimum uses of expensive and scarce precious metals. Metallic glasses (MGs) or amorphous alloys show up as attractive HER catalysts, but have so far limited to material forms and compositions that result in high precious-metal loadings. Here, an Ir₂₅Ni₃₃Ta₄₂ MG nanofilm exhibiting high intrinsic activity and superior stability at an ultralow Ir loading of 8.14 µg cm⁻² for HER in 0.5 m H₂SO₄ is reported. With an overpotential of 99 mV for a current density of 10 mA cm⁻², a small Tafel slope of 35 mV dec⁻¹, and high turnover frequencies of 1.76 and 19.3 H₂ s⁻¹ at 50 and 100 mV overpotentials, the glassy film is among the most intrinsically active HER catalysts, outcompetes any reported MG, representative sulfides, and phosphides, and compares favorably with other precious-metal-containing catalysts. The outstanding HER performance of the Ir₂₅Ni₃₃Ta₄₂ MG film is attributed to the synergistic effect of the novel alloy system and amorphous structure, which may inspire the development of multicomponent alloys for heterogeneous catalysis.     

Tape-Casting Li0.34La0.56TiO3 Ceramic Electrolyte Films Permit High Energy Density of Lithium-Metal Batteries

Ceramic oxide electrolytes are outstanding due to their excellent thermostability, wide electrochemical stable windows, superior Li-ion conductivity, and high elastic modulus compared to other electrolytes. To achieve high energy density, all-solid-state batteries require thin solid-state electrolytes that are dozens of micrometers thick due to the high density of ceramic electrolytes. Perovskite-type Li_0.34La_0.56TiO₃ (LLTO) freestanding ceramic electrolyte film with a thickness of 25 µm is prepared by tape-casting. Compared to a thick electrolyte (>200 µm) obtained by cold-pressing, the total Li ionic conductivity of this LLTO film improves from 9.6 × 10⁻⁶ to 2.0 × 10⁻⁵ S cm⁻¹. In addition, the LLTO film with a thickness of 25 µm exhibits a flexural strength of 264 MPa. An all-solid-state Li-metal battery assembled with a 41 µm thick LLTO exhibits an initial discharge capacity of 145 mAh g⁻¹ and a high capacity retention ratio of 86.2% after 50 cycles. Reducing the thickness of oxide ceramic electrolytes is crucial to reduce the resistance of electrolytes and improve the energy density of Li-metal batteries.     

Sustainable and Scalable Synthesis of 2D Ultrathin Hierarchical Porous Carbon Nanosheets for High-Performance Supercapacitor

2D carbon nanomaterials such as graphene, carbon nanosheets, and their derivatives, representing the emerging class of advanced multifunctional materials, have gained great research interest because of their extensive applications ranging from electrochemistry to catalysis. However, sustainable and scalable synthesis of 2D carbon nanosheets (CNs) with hierarchical architecture and irregular structure via a green and low-cost strategy remains a great challenge. Herein, prehydrolysis liquor (PHL), an industrial byproduct of the pulping industry, is first employed to synthesize CNs via a simple hydrothermal carbonization technique. After mild activation with NH₄Cl and FeCl₃, the as-prepared activated CNs (A-CN@NFe) display an ultrathin structure (≈3 nm) and a desirable specific surface area (1021 m² g⁻¹) with hierarchical porous structure, which enables it to be both electroactive materials and structural support materials in nanofibrillated cellulose/A-CN@NFe/polypyrrole (NCP) nanocomposite, and thus endowing nanocomposite with impressive capacitance properties of 2546.3 mF cm⁻² at 1 mA cm⁻². Furthermore, the resultant all-solid-state symmetric supercapacitor delivers a satisfactory energy storage ability of 90.1 µWh cm⁻² at 250.0 µW cm⁻². Thus, this work not only opens a new window for sustainable and scalable synthesis of CNs, but also offers a double profits strategy for energy storage and biorefinery industry.     

Ultra-Low Pt Doping and Pt–Ni Pair Sites in Amorphous/Crystalline Interfacial Electrocatalyst Enable Efficient Alkaline Hydrogen Evolution

Noble metal doping can achieve an increase in mass activity (MA) without sacrificing catalysis efficiency and stability, so that alkaline hydrogen evolution reaction (HER) performance of the catalyst can be optimized to the maximum degree. However, its excessively large ionic radius makes it difficult to achieve either interstitial doping or substitutional doping under mild conditions. Herein, a hierarchical nanostructured electrocatalyst with enriched amorphous/crystalline interfaces for high-efficiency alkaline HER is reported, which is composed of amorphous/crystalline (Co, Ni)₁₁(HPO₃)₈(OH)₆ homogeneous hierarchical structure with an ultra-low doped Pt (Pt-a/c-NiHPi). Benefiting from the structural flexibility of the amorphous component, extremely low Pt (0.21 wt.%, totally 3.31 µg Pt on 1 cm⁻² NF) are stably doped on it via a simple two-phase hydrothermal method. The DFT calculations show that due to the strongly electron transfer between the crystalline/amorphous components at the interfaces, electrons finally concentrate toward Pt and Ni in the amorphous components, thus the electrocatalyst has near-optimal energy barriers and adsorption energy for H₂O^* and H^*. With the above benefits, the obtained catalyst exhibits an exceptionally high MA (39.1 mA µg⁻¹_Pt) at 70 mV, which is almost the highest level among the reported Pt-based electrocatalysts for alkaline HER.     

Enhanced Crystallinity,Dielectric, and Energy Harvesting Performances of Surface‐Treated Barium Titanate Hollow Nanospheres/PVDF Nanocomposites

Enhancement of the energy harvesting performance and dielectric constants of poly(vinylidene fluoride) (PVDF)‐based capacitors is realized by incorporating 16 wt% of surface‐treated BaTiO₃ hollow nanospheres (HNSs) in comparison with the pristine PVDF. The fabricated BaTiO₃ HNSs with particle sizes of ≈20 nm and BET surface area of 297 m² g⁻¹ are treated by three different surface modifiers. The changes in crystallinity of the PVDF containing the surface‐treated BaTiO₃ HNSs are induced by both enlarged surface areas and increased surface functionality of the HNSs. Effects of such surface functionalities on the crystalline, dielectric, and energy harvesting performances of the nanocomposites are systematically investigated to identify the optimal surface modifier to enhance the energy density of the nanocomposites. Consequently, these changes in crystallinity lead to higher dielectric constants (ε′ ≈ 109.6) and energy density (U_e ≈ 21.7 J cm⁻³) with highly retained breakdown strength (E = 3.81 × 10³ kV cm⁻¹) compared to pristine PVDF (ε′ ≈ 11.6 and U_e ≈ 2.16 J cm⁻³ at 3.98 × 10³ kV cm⁻¹), indicating their potential as high energy density capacitors.     

Boosting Electrochemical Catalysis and Nonenzymatic Sensing Toward Glucose by Single-Atom Pt Supported on Cu@CuO Core–Shell Nanowires

It is critical to develop high-performance electrocatalyst for electrochemical nonenzymatic glucose sensing. In this work, a single-atom Pt supported on Cu@CuO core–shell nanowires (Pt₁/Cu@CuO NWs) for electrochemical nonenzymatic glucose sensor is designed. Pt₁/Cu@CuO NWs exhibit excellent electrocatalytic oxidation toward glucose with 70 mV lower onset potential (0.131 V) and 2.4 times higher response current than Cu NWs. Sensors fabricated using Pt₁/Cu@CuO NWs also show high sensitivity (852.163 µA mM⁻¹ cm⁻²), low detection limit (3.6 µM), wide linear range (0.01–5.18 µM), excellent selectivity, and great long-term stability. The outstanding sensing performance of Pt₁/Cu@CuO NWs, investigated by experiments and density functional theory (DFT) calculations, is attributed to the synergistic effect between Pt single atoms and Cu@CuO core–shell nanowires that generates strong binding energy of glucose on the nanowires. The work provides a new pathway for exploring highly active SACs for electrochemical nonenzymatic glucose sensor.     

Centimeter-Sized Single Crystals of Dion-Jacobson Phase Lead-Free Double Perovskite for Efficient X-ray Detection

2D Dion–Jacobson (DJ) phase hybrid perovskites have shown great promise in the photoelectronic field owing to their outstanding optoelectronic performance and superior structural rigidity. However, DJ phase lead-free double perovskites are still a virgin land with direct X-ray detection. Herein, we have designed and synthesized a new DJ phase lead-free layered double perovskite of (HIS)₂AgSbBr₈ ( 1 , HIS²⁺ = histammonium). Centimeter-sized (18 × 10 × 5 mm³) single crystals of 1 are successfully grown via the temperature cooling technique, exhibiting remarkable semiconductive characteristics such as a high resistivity (2.2 × 10¹¹ Ω cm), a low trap state density (3.56 × 10¹⁰ cm⁻³), and a large mobility-lifetime product (1.72 × 10⁻³ cm² V⁻¹). Strikingly, its single-crystal-based X-ray detector shows a high sensitivity of 223 µC Gy⁻¹_air cm⁻² under 33.3 V mm⁻¹, a low detection limit (84.2 nGy_airs⁻¹) and superior anti-fatigue. As far as we know, we firstly demonstrates the potential of 2D DJ phase lead-free hybrid double perovskite in X-ray detection, showing excellent photoelectric response and operational stability. This work will pave a promising pathway to the innovative application of hybrid perovskites for eco-friendly and efficient X-ray detection.     

Conjugated Acetylenic Polymers Grafted Cuprous Oxide as an Efficient Z-Scheme Heterojunction for Photoelectrochemical Water Reduction

As attractive materials for photoeletrochemical hydrogen evolution reaction (PEC HER), conjugated polymers (e.g., conjugated acetylenic polymers [CAPs]) still show poor PEC HER performance due to the associated serious recombination of photogenerated electrons and holes. Herein, taking advantage of the in situ conversion of nanocopper into Cu₂O on copper cellulose paper during catalyzing of the Glaser coupling reaction, a general strategy for the construction of a CAPs/Cu₂O Z-scheme heterojunction for PEC water reduction is demonstrated. The as-fabricated poly(2,5-diethynylthieno[3,2-b]thiophene) (pDET)/Cu₂O Z-scheme heterojunction exhibits a carrier separation efficiency of 16.1% at 0.3 V versus reversible hydrogen electrode (RHE), which is 6.7 and 1.4-times higher respectively than those for pDET and Cu₂O under AM 1.5G irradiation (100 mW cm⁻²) in the 0.1 m Na₂SO₄ aqueous solution. Consequently, the photocurrent of the pDET/Cu₂O Z-scheme heterojunction reaches ≈ 520 µ A cm⁻² at 0.3 V versus RHE, which is much higher than pDET ( ≈ 80 µ A cm⁻²), Cu₂O ( ≈ 100 µ A cm⁻²), and the state-of-the-art cocatalyst-free organic or organic-semiconductor-based heterojunctions/homojunctions photocathodes (1–370 µ A cm⁻²). This work advances the design of polymer-based Z-scheme heterojunctions and high-performance organic photoelectrodes.     

3D-Printed Structure Boosts the Kinetics and Intrinsic Capacitance of Pseudocapacitive Graphene Aerogels

The performance of pseudocapacitive electrodes at fast charging rates are typically limited by the slow kinetics of Faradaic reactions and sluggish ion diffusion in the bulk structure. This is particularly problematic for thick electrodes and electrodes highly loaded with active materials. Here, a surface-functionalized 3D-printed graphene aerogel (SF-3D GA) is presented that achieves not only a benchmark areal capacitance of 2195 mF cm⁻² at a high current density of 100 mA cm⁻² but also an ultrahigh intrinsic capacitance of 309.1 µF cm⁻² even at a high mass loading of 12.8 mg cm⁻². Importantly, the kinetic analysis reveals that the capacitance of SF-3D GA electrode is primarily (93.3%) contributed from fast kinetic processes. This is because the 3D-printed electrode has an open structure that ensures excellent coverage of functional groups on carbon surface and facilitates the ion accessibility of these surface functional groups even at high current densities and large mass loading/electrode thickness. An asymmetric device assembled with SF-3D GA as anode and 3D-printed GA decorated with MnO₂ as cathode achieves a remarkable energy density of 0.65 mWh cm⁻² at an ultrahigh power density of 164.5 mW cm⁻², outperforming carbon-based supercapacitors operated at the same power density.     

Significantly Stabilizing Hydrogen Evolution Reaction Induced by Nb-Doping Pt/Co(OH)2 Nanosheets

High stability and efficiency of electrocatalysts are crucial for hydrogen evolution reaction (HER) toward water splitting in an alkaline media. Herein, a novel nano-Pt/Nb-doped Co(OH)₂ (Pt/Nb Co(OH)₂) nanosheet is designed and synthesized using water-bath treatment and solvothermal reduction approaches. With nano-Pt uniformly anchored onto Nb Co(OH)₂ nanosheet, the synthesized Pt/Nb Co(OH)₂ shows outstanding electrocatalytic performances for alkaline HER, achieving a high stability for at least 33 h, a high mass activity of 0.65 mA µg⁻¹ Pt, and a good catalytic activity with a low overpotential of 112 mV at 10 mA cm⁻². Both experimental and theoretical results prove that Nb-doping significantly optimizes the hydrogen adsorption free energy to accelerate the Heyrovsky step for HER, and boosts the adsorption of H₂O, which further enhances the water activation. This study provides a new design methodology for the Nb-doped electrocatalysts in an alkaline HER field by facile and green way.     

Oxide-Based Electrolyte-Gated Transistors for Spatiotemporal Information Processing

Spiking neural networks (SNNs) sharing large similarity with biological nervous systems are promising to process spatiotemporal information and can provide highly time- and energy-efficient computational paradigms for the Internet-of-Things and edge computing. Nonvolatile electrolyte-gated transistors (EGTs) provide prominent analog switching performance, the most critical feature of synaptic element, and have been recently demonstrated as a promising synaptic device. However, high performance, large-scale EGT arrays, and EGT application for spatiotemporal information processing in an SNN are yet to be demonstrated. Here, an oxide-based EGT employing amorphous Nb₂O₅ and Li_xSiO₂ is introduced as the channel and electrolyte gate materials, respectively, and integrated into a 32 × 32 EGT array. The engineered EGTs show a quasi-linear update, good endurance (10⁶) and retention, a high switching speed of 100 ns, ultralow readout conductance ( < 100 nS), and ultralow areal switching energy density (20 fJ µ m⁻²). The prominent analog switching performance is leveraged for hardware implementation of an SNN with the capability of spatiotemporal information processing, where spike sequences with different timings are able to be efficiently learned and recognized by the EGT array. Finally, this EGT-based spatiotemporal information processing is deployed to detect moving orientation in a tactile sensing system. These results provide an insight into oxide-based EGT devices for energy-efficient neuromorphic computing to support edge application.     

Electronic-Grade High-Quality Perovskite Single Crystals by a Steady Self-Supply Solution Growth for High-Performance X-ray Detectors

High-quality perovskite single crystals with large size are highly desirable for the fundamental research and high energy detection application. Here, a simple and convenient solution method, featuring continuous-mass transport process (CMTP) by a steady self-supply way, is shown to keep the growth of semiconductor single crystals continuously stable at a constant growth rate until an expected crystal size is achieved. A significantly reduced full width at half-maximum (36 arcsec) of the (400) plane from the X-ray rocking curve indicates a low angular dislocation of 6.8 × 10⁶ cm⁻² and hence a higher crystalline quality for the CH₃NH₃PbI₃(MAPbI₃) single crystals grown by CMTP as compared to the conventional inverse temperature crystallization (ITC) method. Furthermore, the CMTP-based single crystals have lower trap density, reduced by nearly 200% to 4.5 × 10⁹ cm⁻³, higher mobility increased by 187% to 150.2 cm² V⁻¹ s⁻¹, and higher mobility–lifetime product increased by around 450% to 1.6 × 10⁻³ cm² V⁻¹, as compared with the ITC-grown reference sample. The high performance of the CMTP-based MAPbI₃ X-ray detector is comparable to that of a traditional high-quality CdZnTe device, indicating the CMTP method as being a cost-efficient strategy for high-quality electronic-grade semiconductor single crystals.     

Dynamic Reconstructed RuO2/NiFeOOH with Coherent Interface for Efficient Seawater Oxidation

Developing efficient oxygen evolution reaction (OER) electrocatalysts for seawater electrolysis is still a big challenge. Herein, a facile one-pot approach is reported to synthesize RuO₂-incorporated NiFe-metal organic framework (RuO₂/NiFe-MOF) with unique nanobrick-nanosheet heterostructure as precatalyst. Driven by electric field, the RuO₂/NiFe-MOF dynamically reconstructs into RuO₂ nanoparticles-anchored NiFe oxy/hydroxide nanosheets (RuO₂/NiFeOOH) with coherent interface, during which the dissolution and redeposition of RuO₂ are witnessed. Owing to the synergistic interaction between RuO₂ and NiFeOOH, the as-reconstructed RuO₂/NiFeOOH exhibits outstanding alkaline OER activity with an ultralow overpotential of 187.6 mV at 10 mA cm⁻² and a small Tafel slope of 31.9 mV dec⁻¹ and excellent durability at high current densities of 840 and 1040 mA cm⁻² in 1 m  potassium hydroxide (KOH). When evaluated for seawater oxidation, the RuO₂/NiFeOOH only needs a low overpotential of 326.2 mV to achieve 500 mA cm⁻² and can continuously catalyze OER at 500 mA cm⁻² for 100 h with negligible activity degradation. Density function theory calculations reveal that the presence of strong interaction and enhanced charge transfer along the coherent interface between RuO₂ and NiFeOOH ensures improved OER activity and stability.     

Dynamic Pluronic F127 Crosslinking Enhancement of Biopolymeric Nanocomposites for Piezo-Triboelectric Single-Hybrid Nanogenerators and Self-Powered Sensors (Small 21/2023)

Biomechanical and nanomechanical energy harvesting systems have gained a wealth of interest, resulting in a plethora of research into the development of biopolymeric-based devices as sustainable alternatives. Piezoelectric, triboelectric, and hybrid nanogenerator devices for electrical applications are engineered and fabricated using innovative, sustainable, facile-approach flexible composite films with high performance based on bacterial cellulose and BaTiO₃, intrinsically and structurally enhanced by Pluronic F127, a micellar cross-linker. The voltage and current outputs of the modified versions with multiwalled carbon nanotube as a conductivity enhancer and post-poling effect are 38 V and 2.8 µA cm⁻², respectively. The multiconnective devices’ power density can approach 10 µW cm⁻². The rectified output power is capable of charging capacitors, driving light-emitting diode lights, powering a digital watch and interfacing with a commercial microcontroller board to operate as a piezoresistive force sensor switch as a proof of concept. Magnetoelectric studies show that the composites have the potential to be incorporated into magnetoelectric systems. The biopolymeric composites prove to be desirable candidates for multifunctional energy harvesters and electronic devices.     

A High-Energy Asymmetric Supercapacitor Based on Tomato-Leaf-Derived Hierarchical Porous Activated Carbon and Electrochemically Deposited Polyaniline Electrodes for Battery-Free Heart-Pulse-Rate Monitoring

A simple and scalable method to fabricate a novel high-energy asymmetric supercapacitor using tomato-leaf-derived hierarchical porous activated carbon (TAC) and electrochemically deposited polyaniline (PANI) for a battery-free heart-pulse-rate monitor is reported. In this study, TAC is prepared by simple pyrolysis, exhibiting nanosheet-type morphology and a high specific surface area of ≈1440 m² g⁻¹, and PANI is electrochemically deposited onto carbon cloth. The TAC- and PANI- based asymmetric supercapacitor demonstrates an electrochemical performance superior to that of symmetric supercapacitors, delivering a high specific capacitance of 248 mF cm⁻² at a current density of 1.0 mA cm⁻². The developed asymmetric supercapacitor shows a high energy density of 270 µWh cm⁻² at a power density of 1400 µW cm⁻², as well as an excellent cyclic stability of ≈95% capacitance retention after 10 000 charging–discharging cycles while maintaining ≈98% Coulombic efficiency. Impressively, the series-connected asymmetric supercapacitors can operate a battery-free heart-pulse-rate monitor extremely efficiently upon solar-panel charging under regular laboratory illumination.     

Interfacial Engineering of Polycrystalline Pt5P2 Nanocrystals and Amorphous Nickel Phosphate Nanorods for Electrocatalytic Alkaline Hydrogen Evolution

Electrocatalytic hydrogen evolution reaction (HER) in alkaline media is important for hydrogen economy but suffers from sluggish reaction kinetics due to a large water dissociation energy barrier. Herein, Pt₅P₂ nanocrystals anchoring on amorphous nickel phosphate nanorods as a high-performance interfacial electrocatalyst system (Pt₅P₂ NCs/a-NiPi) for the alkaline HER are demonstrated. At the unique polycrystalline/amorphous interface with abundant defects, strong electronic interaction, and optimized intermediate adsorption strength, water dissociation is accelerated over abundant oxophilic Ni sites of amorphous NiPi, while hydride coupling is promoted on the adjacent electron-rich Pt sites of Pt₅P₂. Meanwhile, the ultra-small-sized Pt₅P₂ nanocrystals and amorphous NiPi nanorods maximize the density of interfacial active sites for the Volmer–Tafel reaction. Pt₅P₂ NCs/a-NiPi exhibits small overpotentials of merely 9 and 41 mV at −10 and −100 mA cm⁻² in 1 M KOH, respectively. Notably, Pt₅P₂ NCs/a-NiPi exhibits an unprecedentedly high mass activity (MA) of 14.9 mA µg_Pt⁻¹ at an overpotential of 70 mV, which is 80 times higher than that of Pt/C and represents the highest MA of reported Pt-based electrocatalysts for the alkaline HER. This work demonstrates a phosphorization and interfacing strategy for promoting Pt utilization and in-depth mechanistic insights for the alkaline HER.     

Boosting the Thermoelectric Performance of the Doped DPP-EDOT Conjugated Polymer by Incorporating an Ionic Additive

The thermoelectric (TE) performance of organic materials is limited by the coupling of Seebeck coefficient and electrical conductivity. Herein a new strategy is reported to boost the Seebeck coefficient of conjugated polymer without significantly reducing the electrical conductivity by incorporation of an ionic additive DPPNMe₃Br . The doped polymer PDPP - EDOT thin film exhibits high electrical conductivity up to 1377 ± 109 S cm⁻¹ but low Seebeck coefficient below 30 µV K⁻¹ and a maximum power factor of 59 ± 10 µW m⁻¹ K⁻². Interestingly, incorporation of small amount (at a molar ratio of 1:30) of DPPNMe₃Br into PDPP - EDOT results in the significant enhancement of Seebeck coefficient along with the slight decrease of electrical conductivity after doping. Consequently, the power factor (PF) is boosted to 571 ± 38 µW m⁻¹ K⁻² and ZT reaches 0.28 ± 0.02 at 130 °C, which is among the highest for the reported organic TE materials. Based on the theoretical calculation, it is assumed that the enhancement of TE performance for the doped PDPP - EDOT by DPPNMe₃Br is mainly attributed to the increase of energetic disorder for PDPP - EDOT .     

Gradient-Structured Ceramics with High Energy Storage Performance and Excellent Stability

Owing to the high power density, eco-friendly, and outstanding stability, the lead-free ceramics have attracted great interest in the fields of pulsed power systems. Nevertheless, the low energy storage density of such ceramics is undoubtedly a severe problem in practical applications. To overcome this limitation, the lead-free ceramics with gradient structures are designed and fabricated using the tape-casting method herein. By optimizing the composition and distribution of the gradient-structured ceramics, the energy storage density, and efficiency can be improved simultaneously. Under a moderate electric field of 320 kV cm⁻¹, the value of recoverable energy storage density (W_rec) is higher than 4 J cm⁻³, and the energy storage efficiency (η) is of ≥88% for 20-5-20 and 20-10-20. Furthermore, the gradient-structured ceramics of 20-10-0-10-20 and 20-15-0-15-20 possess high applied electric field, large maximum polarization, and small remnant polarization, which give rise to ultrahigh W_rec and η on the order of ≈6.5 J cm⁻³ and 89–90%, respectively. In addition, the energy storage density and efficiency also exhibit excellent stability over a broad range of frequencies, temperatures, and cycling numbers. This work provides an effective strategy for improving the energy storage capability of eco-friendly ceramics.