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The stereochemical expression of the ns2 lone pair significantly impacts symmetry breaking and corresponding photoelectric properties. However, hindered by the symmetric octahedral configuration, the Pb2+ 6s2 lone pair in the well‐conductive lead halide hybrid perovskites (LHHP) are normally stereo‐inactive, new approaches to activate the 6s2 lone pair are still greatly desired. Herein, by exploiting a perovskitizer tuning Pb2+ lone pair method, the study successfully obtains a stereo‐active 6s2 in the polar perovskite PA2MHy2Pb3Br10 (PMPB, PA = n‐propylamine, MHy = methylhydrazine), and unprecedentedly performs a multiaxial self‐powered X‐ray detection. In detail, the stereo‐active 6s2 lone pair is caused by the coordination bond between the perovskitizer MHy and Pb atom. Emphatically, the N‐Pb bond induces a large angular distortion parameter (≈45 times larger than other LHHP) and the lowest‐symmetric space group (P1) crystallization. Therefore, PMPB natively contains multiaxial polarization, which acts as the driving force to separate and transport the X‐ray‐generated carriers, thus enabling multiaxial self‐powered X‐ray detection with a low detection limit (129 nGy s−1). This work reveals the relationship between stereo‐active lone pair and polarization and sheds light on future X‐ray detection. [ABSTRACT FROM AUTHOR]

High carrier recombination causes a huge waste of photogenic charge, which severely restrains the photocatalytic efficiency. Creating polarization electric field by polar photocatalytic materials proves effective to promote charge separation, while developing efficient polarization strategy is challenging and the related micromechanism remains obscure. Here, overall polarization is achieved in Bi2MoO6 single crystal photocatalyst by lateral growth of the nanoplate along {010} facets. Gradual elongation of equatorial Mo─O bonds along the MoO6 octahedral layer occurs, while the length of apical Mo─O bonds basically remains unchanged, thus allowing the large asymmetric distortion of MoO6 octahedron for producing the microscopic polarization. Meanwhile, the lateral growth of Bi2MoO6 nanoplates enables the accumulation of distorted polar units, further increasing the polarization intensities. The inside‐out crystal polarization significantly promotes the separation and migration of photogenerated charge carriers. The finely polarized Bi2MoO6 nanoplates exhibit an exceptional photocatalytic selective oxidation rate of benzyl alcohol (BA) to benzaldehyde (BAD) under visible light irradiation (Conversion (Con.) ≈100% within 30 min, Selectivity (Sel.) ≥95%), over 70.7 times that of original Bi2MoO6 nanosheets, on the condition of comparable O2 adsorption capability. This study advances atomic‐level mechanistic insight into polarized materials toward precise design of high‐performance photocatalysts. [ABSTRACT FROM AUTHOR]

NaBiCe/Sc ions were co‐doped into a pure CaBi4Ti4O15 (CBT) ceramic to investigate the synergistic action of multiple factors that induced a high piezoresponse. In comparison to the undoped CBT ceramic, the NaBiCe/Sc co‐doped CBT solid solution exhibited an enhancement in spontaneous polarization (Ps) attributed to the tilting of the oxygen octahedra, enhanced domain reorientation owing to increased grain size, and improved dielectric breakdown strength as a consequence of reduced porosity. The synergistic action of the aforementioned comprehensive factors resulted in excellent electrical properties of Ca0.6(Na0.5Bi0.5)0.4Bi3.97Ce0.03Ti3.925Sc0.075O15 ceramic: piezoelectric coefficient d33 = 25.0 pC/N, remnant polarization Pr = 9.28 μC/cm2, and coercive field Ec = 76.14 kV/cm. Moreover, a significant high direct current resistivity (ρdc = 1.22 × 107 Ω·cm at 500°C) was achieved, and the corresponding conductance mechanism was analyzed through a synergistic approach that combines ultraviolet–visible diffuse reflectance spectra and density functional theory. [ABSTRACT FROM AUTHOR]

An efficient carrier injection at the electrode/organic semiconductor interface of organic light‐emitting diodes (OLEDs) is challenging. It is well‐known that an electric dipole at the electrode/semiconductor interface improves the carrier injection from the electrode because of a vacuum‐level shift. In this study, poly (vinylidene fluoride‐trifluoroethylene) [P(VDF/TrFE)] is used as a polar polymer with spontaneous polarization. P(VDF/TrFE) is spin‐coated on an indium tin oxide (ITO) electrode surface as a hole injection layer for OLEDs. The P(VDF/TrFE) layer enhances the hole injection from the ITO electrode by causing a vacuum‐level shift. As a result, the device driving voltage can be lowered. In addition, annealing temperature dependence is observed. To investigate the origin of the hole injection effect, the P(VDF/TrFE)‐layered ITO surface and the thin film structure of the P(VDF/TrFE) layer are measured. The P(VDF/TrFE) layers at different annealing temperatures show no difference in surface properties but show significant differences in the thin film structure. The hole injection of OLEDs is significantly enhanced because of the structural change in ultrathin P(VDF/TrFE) layer. [ABSTRACT FROM AUTHOR]

Pyroelectric materials in the field of photoelectrochemical (PEC) water splitting still face the problems of difficult low spontaneous polarization intensity and excessive carrier recombination. Based on the above problems, we altered the interaction between S−Nb−S in the [NbO]6−x‐xS structure, and the constructed [NbO]6−x‐xS structure achieved the regulation of charge density change and spontaneous polarization. The results show that under the stimulation of light and temperature fluctuations, the current density of the NS‐4 photoanode is as high as 0.574 mA/cm2 at 1.23 VRHE, which is about 1.59 times higher than the pure NaNbO3 current density value, and the NS −4 photoanode achieves IPCE value of 16.08 %. The first‐principles density‐functional theory calculations (DFT) reveal the principle of the [NbO]6−x‐xS structure for the suppression function of the carrier recombination and the improvement function of the pyroelectric effect. The analysis shows that the S‐doping leads to the weakening of S−Nb−S interactions in the [NbO]6−x‐xS structure, which improves the pyroelectric effect and suppresses the photo/pyro‐generated carrier recombination, and effectively enhances the performance of the pyro‐photo‐electric synergistic water splitting system. This work promotes the development of pyroelectric materials in the field of photoelectrochemical water splitting. [ABSTRACT FROM AUTHOR]

Pyroelectric materials in the field of photoelectrochemical (PEC) water splitting still face the problems of difficult low spontaneous polarization intensity and excessive carrier recombination. Based on the above problems, we altered the interaction between S−Nb−S in the [NbO]6−x‐xS structure, and the constructed [NbO]6−x‐xS structure achieved the regulation of charge density change and spontaneous polarization. The results show that under the stimulation of light and temperature fluctuations, the current density of the NS‐4 photoanode is as high as 0.574 mA/cm2 at 1.23 VRHE, which is about 1.59 times higher than the pure NaNbO3 current density value, and the NS −4 photoanode achieves IPCE value of 16.08 %. The first‐principles density‐functional theory calculations (DFT) reveal the principle of the [NbO]6−x‐xS structure for the suppression function of the carrier recombination and the improvement function of the pyroelectric effect. The analysis shows that the S‐doping leads to the weakening of S−Nb−S interactions in the [NbO]6−x‐xS structure, which improves the pyroelectric effect and suppresses the photo/pyro‐generated carrier recombination, and effectively enhances the performance of the pyro‐photo‐electric synergistic water splitting system. This work promotes the development of pyroelectric materials in the field of photoelectrochemical water splitting. [ABSTRACT FROM AUTHOR]

Gadolinium (Gd) and Nickel (Ni) doped bismuth ferrite (BiFeO3) nanoparticles Bi0.925Gd.075Fe0.95Ni0.05O3 (BGFNO) with spontaneous polarization (2.5 μC/cm2) were mechano‐chemically synthesized and used to achieve high capacity retention in lithium sulfur (Li−S) batteries. The BGFNO particles were coupled with single walled carbon nanotubes (SWCNT)/sulfur (S) composite cathodes as well as coated on separator. The X‐ray diffraction of BGFNO@S/SWCNT cathodes show an orthorhombic structure with particle size distribution of 20–26 nm, while Raman spectra substantiate efficient coupling of BGFNO with S/SWCNT cathodes, in agreement with SEM images, showing the interconnected network of composites. The specific discharge capacity of S60BGFNO30SWCNT10 composite cathode @ 200 mA/g together with BGFNO coated separator gains maximum capacity up to 1611 mAh/g and retains up to 1294 mAh/g after 50th cycle with improved capacity retention of 80 % showing suppression of polysulfides formation. The coated separator controls transport of carrier ions and side reactions, however modified cathodes with BGFNO particles acts as trapping center for polysulfides to enhance the electrochemical performance of the cells. The Coulombic efficiency(CE) for BGFNO/S/SWCNT composites @ 100 mA/g attained >98 % and CE @ 200 mA/g it is attained > 80 to 90 % compared to S/SWCNT composites in terms of improved cycle stability and reaction kinetics. [ABSTRACT FROM AUTHOR]

High energy density and intrinsic safety are the central pursuits in developing rechargeable Zinc‐ion batteries (ZIBs). The capacity and stability of nickel cobalt oxide (NCO) cathode are unsatisfactory because of its semiconductor character. Herein, we propose a built‐in electric field (BEF) approach by synergizing cationic vacancies and ferroelectric spontaneous polarization on cathode side to facilitate electron adsorption and suppress zinc dendrite growth on the anode side. Concretely, NCO with cationic vacancies was constructed to expand lattice spacing for enhanced zinc‐ion storage. Heterojunction with BEF leads to the Heterojunction//Zn cell exhibiting a capacity of 170.3 mAh g−1 at 400 mA g−1 and delivering a competitive capacity retention of 83.3 % over 3000 cycles at 2 A g−1. We conclude the role of spontaneous polarization in suppressing zinc dendrite growth dynamics, which is conducive to developing high‐capacity and high‐safety batteries via tailoring defective materials with ferroelectric polarization on the cathode. [ABSTRACT FROM AUTHOR]

Tourmaline (TM) has received extensive interest in the purification field due to its unique spontaneous polarization. In this paper, the effects of three sizes of purified TM samples on the air filters were studied. The electrode performance of TM samples was investigated using piezoelectric and pyro‐electric experiments. The results show an electrode from the 0.074 mm separated TM had the superior property. Three types of TM powders with the highest B2O3% content were adhered to the filter to evaluate the filtration performance. Elbaite 0.074 mm with 9.34 B2O3% content had the optimal filtration efficiency when the pressure drop increased slightly. The Rietveld method was used to refine the samples X‐Ray diffraction patterns to obtain the crystal structure. The electrostatic adsorption caused by the TM spontaneous polarization contributes to improving the filtration property of the filter materials. [ABSTRACT FROM AUTHOR]

Polar crystals have attracted interest for the applications to polar materials with piezo‐ and pyroelectricity, and second harmonic generation. Despite their potential utility for flexible polar materials, a strategy for ordering polar helicenes has remained elusive. Here, we demonstrate the creation of polar crystals with unsymmetrically substituted aza[5]helicenes tuned by substituents. The unsymmetric aza[5]helicenes have been prepared through regioselective mono‐protiodesilylations. We disclose that triisopropylsilyl‐substituted derivatives show 1D chain columnar packings. In particular, enantiopure crystals showed spontaneous polarization. Optical and single‐crystal X‐ray diffraction experiments with other derivatives, as well as theoretical calculations, revealed that the presence of triisopropylsilyl or electron‐withdrawing aryl substituents is essential for forming the 1D chain columnar structure. Hirshfeld surface analyses further showed that CH‐π interactions between 1D chain columns regulate the polar assembly. Finally, we determined the polarizability of the nitro derivative by ab initio calculation to be 4.53 μC/cm2. This value corroborates the first example of a spontaneously polar crystal of helicenes. We believe that this study will contribute to the development of polar materials from organic molecules. [ABSTRACT FROM AUTHOR]

The ambient pressure cation disordered InVO3 bixbyite has been predicted to form a GdFeO3‐type perovskite phase under high pressure and high temperature. Contrary to the expectation, InVO3 was found to crystallize in the polar LiNbO3‐type structure with a calculated spontaneous polarization as large as 74 μC cm−2. Antiferromagnetic coupling of V3+ magnetic moments and a cooperative magnetic ground state below about 10 K coupled with a polar structure suggest an intriguing ground state of the novel LiNbO3‐type high‐pressure InVO3 structure. [ABSTRACT FROM AUTHOR]

This paper introduces a new method for adjusting the particle size of ZrO2 powder through the electric field effect of tourmaline. The 3 mol% yttria‐stabilized ZrO2 (3YSZ) powder was prepared by using ZrOCl2∙8H2O, YCl3∙6H2O, NaOH, and nano‐tourmaline powder as raw materials through direct precipitation. The powder was characterized with thermogravimetric‐differential scanning calorimeter, X‐ray diffraction, Brunauere‐Emmette‐Teller, Fourier transform infrared, scanning electron microscope, and transmission electron microscope, and the mechanism of tourmaline in the process of powder preparation was also discussed. Findings demonstrate that the electric field generated by spontaneous polarization of tourmaline can control the size of ZrO2 crystal grains, improve the dispersibility of the powder, and promote the stability of ZrO2 in the tetragonal phase. When the electric intensity of tourmaline is 9.02 × 106 V/m, and the addition amount is 2.5 vol%, tourmaline/3YSZ powders are mainly tetragonal phase, and the grain size is the smallest, with an average crystallite size of 19 nm. Then the mechanical properties of tourmaline/3YSZ ceramics were tested. Compared with 3YSZ ceramics without tourmaline, the flexural strength and fracture toughness were improved by 39.5% and 35.8%. [ABSTRACT FROM AUTHOR]

Electro‐optic (EO) modulation allows the conversion of electrical signals to optical pulses and is widely employed in telecommunications and chip‐to‐chip interconnects. Recently, hybrid organic–inorganic perovskites (HOIPs) have been explored as candidates for EO modulators. To improve the EO performance, it is envisioned that halide doping will lower the symmetry of the crystal, enhancing spontaneous polarization. However, mixed halide perovskites are often associated with ion migration, which may impact their EO properties. Thus, the influence of ion migration on the EO efficiency is investigated using Br‐doped Dion–Jacobson quasi‐2D HOIPs, (4AMP)(MA)Pb2(Brx/I1−x)7 (4AMP = 4‐(aminomethyl)piperidinium, MA = methylammonium). While density functional theory predicts a greater spontaneous polarization for the Br‐doped sample, it is found that experimental results are affected by ion migration. The EO coefficient of the Br/I mixed sample is 95 pm V−1 at 1 kHz (≈50× higher than the undoped sample), but the response falls off rapidly with frequency. This frequency dependence is correlated with impedance spectroscopy, showing that the large EO signal results from ion migration. This study shows that ion migration impacts the EO analysis of mixed halide perovskites and must be considered in future EO studies. [ABSTRACT FROM AUTHOR]

It is believed that promoting the fraction of ferroelectric orthorhombic phase (o-phase) through O-poor growth conditions can increase the spontaneous polarization of HfO2 and (Hf,Zr)O2 thin films. However, the first-principles calculations show that the growth may be limited by the easy formation of point defects in the orthorhombic and tetragonal phases of HfO2, ZrO2, and (Hf,Zr)O2. Their dominant defects, O interstitial (Oi) under O-rich conditions and O vacancy (VO) under O-poor condition, have low formation energies and quite high density (1016-1019 cm-3 for 800-1400 K growth temperature). Especially, Oi has negative formation energy in tetragonal HfO2 under O-rich condition, causing non-stoichiometry and limiting the crystalline-seed formation during o-phase growth. High-density defects can cause disordering of dipole moments and increase leakage current, both diminishing the polarization. These results explain the experimental puzzle that the measured polarization is much lower than the ideal value even in O-poor thin films and highlight that controlling defects is as important as promoting the o-phase fraction for enhancing ferroelectricity. The O-intermediate condition (average of O-rich and O-poor conditions) and low growth temperature are proposed for fabricating HfO2 and (Hf,Zr)O2 with fewer defects, lower leakage current, and stronger ferroelectricity, which challenges the belief that O-poor condition is optimal. [ABSTRACT FROM AUTHOR]

GaAs‐based semiconductors are highly attractive for diverse nonlinear photonic applications, owing to their non‐centrosymmetric crystal structure and huge nonlinear optical coefficients. Nanostructured semiconductors, for example, nanowires (NWs), offer rich possibilities to tailor nonlinear optical properties and further enhance photonic device performance. In this study, it is demonstrated highly efficient second‐harmonic generation in subwavelength wurtzite (WZ) GaAs NWs, reaching 2.5 × 10−5 W−1, which is about seven times higher than their zincblende counterpart. This enhancement is shown to be predominantly caused by an axial built‐in electric field induced by spontaneous polarization in the WZ lattice via electric field‐induced second‐order nonlinear susceptibility and can be controlled optically and potentially electrically. The findings, therefore, provide an effective strategy for enhancing and manipulating the nonlinear optical response in subwavelength NWs by utilizing lattice engineering. [ABSTRACT FROM AUTHOR]

For ferroelectric applications, wurtzite (WZ)‐phase (Al,Sc)N is investigated using ab initio calculations. The key ferroelectric properties, such as the ferroelectric switching barrier and spontaneous polarization, are examined in (AlN)n/(ScN)m superlattice (SL) structures by varying the ScN fraction, and compared with an (Al,Sc)N solid solution (SS). The reduction of the switching barrier is dominated by the local structural instability rather than the flattening of the buckled monolayer composed of metal–nitrogen pairs in WZ‐stacking. This argument is supported by the doping effects of other metal elements as well as the reduction of the switching barrier in the SL, which does not accompany the flattening of the buckled monolayer. The decrease in the spontaneous polarization along the ScN fraction is explained by structural parameters (the in‐plane area and the buckling parameter) and the Born effective charge (BEC). The slight decrease in the spontaneous polarization in the SL is attributed to the larger increase in the in‐plane area rather than the BEC. In contrast, the decrease in the buckling parameter in the SS is suggested to more significantly reduce the spontaneous polarization along the ScN fraction. [ABSTRACT FROM AUTHOR]

The gap in understanding how underlying chemical dynamics impact the functionality of metal halide perovskites (MHPs) leads to the controversy about the origin of many phenomena associated with ion migration in MHPs. In particular, the debate regarding the impact of ion migration on current–voltage (I–V) hysteresis of MHPs devices has lasted for many years, where the difficulty lies in directly uncovering the chemical dynamics, as well as identifying and separating the impact of specific ions. In this work, using a newly developed time‐resolved time‐of‐flight secondary ion mass spectrometry CH3NH3+ and I− migrations in CH3NH3PbI3 are directly observed, revealing hysteretic CH3NH3+ and I− migrations. Additionally, hysteretic CH3NH3+ migration is illumination‐dependent. Correlating these results with the I–V characterization, this work uncovers that CH3NH3+ redistribution can induce a remanent field leading to a spontaneous current in the device. It unveils that the CH3NH3+ migration is responsible for the illumination‐associated I–V hysteresis in MHPs. Hysteretic ion migration has not been uncovered and the contribution of any ions (e.g., CH3NH3+) has not been specified before. Such insightful and detailed information has up to now been missing, which is critical to improving MHPs photovoltaic performance and developing MHPs‐based memristors and synaptic devices. [ABSTRACT FROM AUTHOR]

The surface of a c− cut ferroelectric crystal at room temperature is characterized by the so‐called screening surface charges, able to compensate the charge due to the spontaneous polarization. Recently, these charges inspired the investigation of the interaction affinity of live cells with lithium niobate and lithium tantalate crystals. However, different knowledge gaps still remain that prevent a reasonable application of these materials for biological applications. Here, a label‐free holographic total internal reflection microscopy is shown; the technique is able to evaluate quantitatively the contact area of live fibroblast cells adhering onto the surface of a ferroelectric lithium niobate crystal. The results show values of contact area significantly different between cells adhering onto the positive or negative face of the crystal. This reinforces the reasons for using the polarization charge of these materials to study and/or control cellular processes and, thus, to develop an innovative platform based on polar dielectric functional substrates. [ABSTRACT FROM AUTHOR]

Polymer Dispersed Ferroelectric Liquid Crystal (PDFLC) composites comprising of ferroelectric liquid crystal (FLC) and Ultra-Violet (UV) curable polymer in different compositions have been synthesized by polymerization induced phase separation (PIPS) method and studied in thin sample cells of thickness 10 μm. Changes in liquid crystal (LC) droplet morphology and droplet size are investigated as a function of polymer concentration. The effect of polymer concentration on electro-optical parameters (polarization, response time and rotational viscosity) has been studied. Faster response time (∼200-400 μsec) was seen in low concentration based PDFLC than higher polymer content PDFLC. [ABSTRACT FROM AUTHOR]

Na0.5K0.5NbO3 has been synthesized by the conventional solid-state reaction process. The crystal structures and phase transitions, at low and high temperature, determined from the Rietveld refinements of X-ray and neutron powder diffraction data are reported. The structure evolution of Na0.5K0.5NbO3 in the temperature range from 2 to 875 K shows the presence of three phase transitions. The first one, at ∼135 K, is discontinuous from the rhombohedral R3 c (No. 161) space group to the room-temperature orthorhombic Amm2 (No. 38) space group; the second is discontinuous from the orthorhombic to the tetragonal P4 mm space group (No. 99) at ∼465 K, and the third is continuous from the tetragonal to the cubic space group (No. 221) at ∼700 K. The obtained phase-transition sequence is R3 c→ Amm2 → P4 mm→ Pm m. No previous studies at low temperature have been carried out on the material with composition Na0.5K0.5NbO3. In the course of the determination of the three experimentally found phases, a novel method of refinement is presented. This is a step forward in the use of the symmetry-adapted modes as degrees of freedom in the refinement process: the parameterization of a direction in the internal space of the, in this case, sole irreducible representation, GM4−, responsible for the symmetry breaking from the parent cubic space group to the polar distorted low-symmetry phases. Eventually, this procedure enables the calculation of the spontaneous polarization. [ABSTRACT FROM AUTHOR]

Na0.5K0.5NbO3 has been synthesized by the conventional solid-state reaction process. The crystal structures and phase transitions, at low and high temperature, determined from the Rietveld refinements of X-ray and neutron powder diffraction data are reported. The structure evolution of Na0.5K0.5NbO3 in the temperature range from 2 to 875 K shows the presence of three phase transitions. The first one, at ∼135 K, is discontinuous from the rhombohedral R3 c (No. 161) space group to the room-temperature orthorhombic Amm2 (No. 38) space group; the second is discontinuous from the orthorhombic to the tetragonal P4 mm space group (No. 99) at ∼465 K, and the third is continuous from the tetragonal to the cubic space group (No. 221) at ∼700 K. The obtained phase-transition sequence is R3 c→ Amm2 → P4 mm→ Pm m. No previous studies at low temperature have been carried out on the material with composition Na0.5K0.5NbO3. In the course of the determination of the three experimentally found phases, a novel method of refinement is presented. This is a step forward in the use of the symmetry-adapted modes as degrees of freedom in the refinement process: the parameterization of a direction in the internal space of the, in this case, sole irreducible representation, GM4−, responsible for the symmetry breaking from the parent cubic space group to the polar distorted low-symmetry phases. Eventually, this procedure enables the calculation of the spontaneous polarization. [ABSTRACT FROM AUTHOR]

The ambient pressure cation disordered InVO3 bixbyite has been predicted to form a GdFeO3‐type perovskite phase under high pressure and high temperature. Contrary to the expectation, InVO3 was found to crystallize in the polar LiNbO3‐type structure with a calculated spontaneous polarization as large as 74 μC cm−2. Antiferromagnetic coupling of V3+ magnetic moments and a cooperative magnetic ground state below about 10 K coupled with a polar structure suggest an intriguing ground state of the novel LiNbO3‐type high‐pressure InVO3 structure. [ABSTRACT FROM AUTHOR]

The sensitivity of spontaneous polarization to epitaxial strain for both 10 and 50 nm thick Ba0.5Sr0.5TiO3 (BSTO) ferroelectric thin films has been studied. Crystal truncation rod (CTR) profiles in the 00 L directions at different wavelengths, and grazing incidence diffraction (GID) in the 0 K0 direction on a single crystal have been recorded. Modeling of the CTR data gives a detailed picture of the strain and provides clear evidence of the film out-of-plane expansion at the surface, an increase of the polarization, as well as a contraction at the interface. GID data confirm the fitting of the CTR, showing an in-plane expansion of the BSTO film at the interface and a contraction at the surface. [ABSTRACT FROM AUTHOR]

Van der Waals (vdW) heterostructures consisting of two‐dimensional‐layered nanomaterials have attracted great attention due to their promising applications in novel electronic and optoelectronic devices. Using density functional theory (DFT) with the vdW correlations (DFT‐D), the electronic properties and spontaneous polarization of graphene/monolayer GeS (G/MGeS) heterostructure have been investigated. It is found that the properties of both graphene and GeS are preserved in the vdW heterostructure, and the electronic structure of the heterostructure is advantageous for improving photocatalytic efficiency. Moreover, it is also found that the position of the band structure of GeS with respect to that of graphene can be tuned by altering the interlayer spacing, which further led to the control of the Schottky barrier height of the vdW heterostructures. Additionally, the vdW heterostructure shows increased spontaneous polarization (186.6 μC cm−2) as well as increased energy barrier heights, which indicate the enhanced ferroelectricity in the heterostructure. Further investigation demonstrates that the compressive strain can have a significant impact on both the spontaneous polarization and the energy barrier height of the vdW heterostructure. [ABSTRACT FROM AUTHOR]

Integration of fuel cells into microfluidic devices requires development of innovative proton conductors. Conventional Nafion membranes are incompatible with planar‐type microfluidic devices and require a high operation temperature of over 100 °C to achieve rapid proton transfer. In contrast, glass nanochannels (NCs) work as proton conductors even at room temperature and can be seamlessly integrated into microfluidic devices, which in turn makes microfuel cells (µFCs) attractive for a wide range of practical applications, such as power sources for ultrasmall autonomous electronics and chemo‐ or biosensors. However, the conductivity of NCs is limited by their small cross‐sectional area. It is revealed that spontaneous polarization of lithium niobite (LiNbO3) used as the NC material enhances a surface charge of a SiO2 layer formed on LiNbO3 and induces a fast proton transfer in water in the NCs. It is demonstrated that a µFC containing the LiNbO3 NCs demonstrates a proton diffusion coefficient that is 1.8 times higher than that of a reference device with bare glass NCs. In addition, such a µFC achieves a remarkable power output of up to ≈54 mW cm−2 at room temperature, which is 1.4 times higher than that of the similar device with bare glass NCs. [ABSTRACT FROM AUTHOR]