Artificial spinal dura mater made of gelatin microfibers and bioadhesive for preventing cerebrospinal fluid leakage.

Artificial spinal dura mater was designed by combining solution blow-spun gelatin microfibers and dopamine-capped polyurethane bioadhesive. Notably, the gelatin microfibers had a special pore structure, good water adsorption capability, and excellent burst pressure resistance. The bioadhesive layer contributed to the excellent sealing performance in the wet state. This material provides a promising alternative as an artificial spinal dura mater to prevent cerebrospinal fluid leakage.

Regulating the Charge Migration in CuInSe2 /N-Doped Carbon Nanorod Arrays via Interfacial Engineering for Boosting Photoelectrochemical Water Splitting.

Regulating the charge migration and separation in photoactive materials is a great challenge for developing photoelectrochemical (PEC) applications. Herein, inspired by capacitors, well-defined CuInSe2 /N-doped carbon (CISe/N-C) nanorod arrays are synthesized by Cu/In-metal organic frame-derived method. Like the charge process of capacitor, the N-doped carbon can capture the photogenerated electron of CISe, and the strong interfacial coupling between CISe and N-doped carbon can modulate the charge migration and separation. The optimized the CISe/N-C photoanode achieves a maximum photocurrent of 4.28 mA cm-2 at 1.23 V versus reversible hydrogen electrode (RHE) in neutral electrolyte solution under AM 1.5 G simulated sunlight (100 mW cm-2 ), which is 8.4 times higher than that of the CuInSe2 photoanode (0.51 mA cm-2 ). And a benefit of the strong electronic coupling between CISe and N-doped carbon, the charge transfer rate is increased to 1.3-13 times higher than that of CISe in the range of 0.6-1.1 V versus RHE. The interfacial coupling effects on modulating the carrier transfer dynamics are investigated by Kelvin probe force microscopy analysis and density functional theory calculation. This work provides new insights into bulk phase carrier modulation to improve the performance of photoanode for PEC water splitting.

High-Performance Electrostrictive Relaxors with Dispersive Endotaxial Nanoprecipitations.

Ultrahigh-precision manufacturing and detection have highlighted the importance of investigating electrostrictive materials with a weak stimulated extrinsic electric field and a simultaneous large hysteresis-free strain. In this study, a new type of electrostrictive relaxor ferroelectric is designed by constructing a complex inhomogeneous local structure to realize excellent electrostrictive properties. A remarkably large electrostrictive coefficient, M33 (8 × 10-16 m2 V-2 ) is achieved. Through a combined atomic-scale scanning transmission electron microscopy and advanced in situ high-energy synchrotron X-ray diffraction analysis, it is observed that such superior electrostrictive properties can be ascribed to a special domain structure that consists of endotaxial nanoprecipitations embedded in a polar matrix at the phase boundary of the rhombohedral/tetragonal/cubic phases. The matrix contributes to the high strain response under the weak extrinsic electric field because of the highly flexible polarization and randomly dispersed endotaxial nanoprecipitations with a nonpolar central region, which provide a strong restoring force that reduces the strain hysteresis. The approach developed in this study is widely applicable to numerous relaxor ferroelectrics, as well as other dielectrics, for further enhancing their electrical properties, such as electrostriction and energy-storage capacity.

High Piezoelectric Performance in Pb(Ni1/3Nb2/3)O3-Pb(Sc1/2Nb1/2)O3-PbTiO3 Ternary System Featuring Small Structural Distortion and Heterogeneous Domain Configuration.

Ternary/polynary perovskite solid solutions based on binary systems are well-known for their high piezoelectric performance. In this work, a series of Pb(Ni1/3Nb2/3)O3-Pb(Sc1/2Nb1/2)O3-PbTiO3 compositions with the particularly high piezoelectric coefficient of d33* > 1000 pm/V and d33 > 700 pC/N have been developed. The optimal performance was achieved in the 0.52PNN-0.14PSN-0.34PT composition (d33* = 1120 pm/V, d33 = 804 pC/N, and Tm = 109 °C). The high piezoelectric performance of this system is reported and is superior to those of most lead-based ternary/polynary ceramics. By a combination of in situ high-energy synchrotron diffraction with transmission electron microscopy (TEM), the origin of the high piezoelectric response has been unambiguously revealed. Upon application of an external electric field, synchrotron diffraction profiles show no splitting but prominent shifting, indicating that the large intrinsic lattice strain arising from the reduced crystal anisotropy and facilitated polarization variation is associated with the high piezoelectric response. Furthermore, microscopic studies by TEM highlight a heterogeneous ferroelectric domain configuration generated by a small local structural distortion, which is also beneficial for the high piezoelectric performance in the proposed ternary piezoelectric systems. The design process of ternary perovskite solid solutions with a wide morphotropic phase boundary region and small structural distortion may be enlightening for the exploration of other high-performance polynary piezoelectrics.

Strong Room-Temperature Ferroelectricity in Strained SrTiO3 Homoepitaxial Film.

Although the discovery of exceptional ferroelectricity in paraelectrics offers great opportunities to enrich the diversity of the ferroelectric family and promote the development of novel functionalities, transformation of paraelectric phases into ferroelectric phases remains challenging. Herein, a method is presented for driving paraelectrics into ferroelectric states via the introduction of M/O-deficient (M for metal) perovskite nanoregions. Using this method, strong ferroelectricity, equivalent to that of classic ferroelectrics, is achieved in a prototype paraelectric strontium titanate (SrTiO3 ) homoepitaxial film embedded with Ti/O-deficient perovskite nanoregions. It is shown that these unique nanoregions impose large out-of-plane tensile strain and electron-doping effects on the matrix to form a tetragonal structure (tetragonality = 1.038), driving the off-center movements of Ti and Sr atoms. This leads to a significant room-temperature ferroelectric polarization (maximum polarization = 41.6 µC cm-2 and spontaneous polarization = 25.2 µC cm-2 at 1.60 MV cm-1 ) with a high thermal stability (Tstable  ≈ 1098 K). The proposed approach can be applied to various paraelectrics for creating ferroelectricity and generating emergent physical properties, opening the door to a new realm of materials design.

Urchin-Like Fe3 Se4 Hierarchitectures: A Novel Pseudocapacitive Sodium-Ion Storage Anode with Prominent Rate and Cycling Properties.

Transition metal chalcogenides have received great attention as promising anode candidates for sodium-ion batteries (SIBs). However, the undesirable cyclic life and inferior rate capability still restrict their practical applications. The design of micro-nano hierarchitectures is considered as a possible strategy to facilitate the electrochemical reaction kinetics and strengthen the electrode structure stability upon repeated Na+ insertion/extraction. Herein, urchin-like Fe3 Se4 hierarchitectures are successfully prepared and developed as a novel anode material for SIBs. Impressively, the as-prepared urchin-like Fe3 Se4 can present an ultrahigh rate capacity of 200.2 mAh g-1 at 30 A g-1 and a prominent capacity retention of 99.9% over 1000 cycles at 1 A g-1 , meanwhile, a respectable initial coulombic efficiency of ≈100% is achieved. Through the conjunct study of in situ X-ray diffraction, ex situ X-ray absorption near-edge structure spectroscopy, as well as cyclic voltammetry curves, it is intriguing to reveal that the phase transformation from monoclinic to amorphous structure accompanied by the pseudocapacitive Na+ storage behavior accounts for the superior electrochemical performance. When paired with the Na3 V2 (PO4 )3 cathode materials, the assembled full cell enables high energy density and decent cyclic stability, demonstrating potential practical feasibility of the present urchin-like Fe3 Se4 anode.

A Novel NASICON-Type Na4 MnCr(PO4 )3 Demonstrating the Energy Density Record of Phosphate Cathodes for Sodium-Ion Batteries.

Sodium-ion batteries (SIBs) have attracted incremental attention as a promising candidate for grid-scale energy-storage applications. To meet practical requirements, searching for new cathode materials with high energy density is of great importance. Herein, a novel Na superionic conductor (NASICON)-type Na4 MnCr(PO4 )3 is developed as a high-energy cathode for SIBs. The Na4 MnCr(PO4 )3 nanoparticles homogeneously embedded in a carbon matrix can present an extraordinary reversible capacity of 160.5 mA h g-1 with three-electron reaction at ≈3.53 V during the Na+ extraction/insertion process, realizing an unprecedentedly high energy density of 566.5 Wh kg-1 in the phosphate cathodes for SIBs. It is intriguing to reveal the underlying mechanism of the unique Mn2+ /Mn3+ , Mn3+ /Mn4+ , and Cr3+ /Cr4+ redox couples via X-ray absorption near-edge structure spectroscopy. The whole electrochemical reaction undergoes highly reversible single-phase and biphasic transitions with a moderate volume change of 7.7% through in situ X-ray diffraction and ex situ high-energy synchrotron X-ray diffraction. Combining density functional theory (DFT) calculations with the galvanostatic intermittent titration technique, the superior performance is ascribed to the low ionic-migration energy barrier and desirable Na-ion diffusion kinetics. The present work can offer a new insight into the design of multielectron-reaction cathode materials for SIBs.