Surface chemistry altering electronic behaviour of liquid metal-derived tin oxide nanosheets.

Possessing excellent electronic properties and high chemical stability, semiconducting n-type two-dimensional (2D) tin dioxide (SnO2) nanosheets have been featured in sensing and electrocatalysis applications recently. Derived from non-layered crystal structures, 2D SnO2 has abundant unsaturated dangling bonds existing at the surface, providing interfacial activity. How the surface chemistry alters the electronic properties of 2D SnO2 nanomaterials remains unexplored. In this study, we synthesised ultra-thin 2D SnO2 nanosheets using a liquid metal (LM) touch printing technique and investigated experimentally and theoretically how the interactions of organic solvents composed of alkyl and hydroxyl groups with the surface of LM-derived 2D SnO2 modulate the electronic properties. It was found that alkane solvents can physically absorb onto the SnO2 surface with no impact on the material conductivity. Alcohol-based solvents on the other hand interact with the SnO2 surface via chemical absorptions primarily, in which oxygen atoms of hydroxyl groups in the alcohols form bonds with the surface atoms of SnO2. The binding stability is determined by the length and configuration of the hydrocarbon chain in alcohols. As representative long-chain alcohols, 1-octanol and 1-pentanol attach onto the SnO2 surface strongly, lowering the binding energy of Sn4+ and reducing the electron transfer ability of SnO2 nanosheets. Consequently, the electronic properties, i.e. conductivity and electronic mobility of SnO2 nanosheet-based electronic devices are decreased significantly.

Defect-Free, Few-Atomic-Layer Thin ZnO Nanosheets with Superior Excitonic Properties for Optoelectronic Devices.

Two-dimensional (2D) wide bandgap materials are gaining significant interest for next-generation optoelectronic devices. However, fabricating electronic-grade 2D nanosheets from non-van der Waals (n-vdW) oxide semiconductors poses a great challenge due to their stronger interlayer coupling compared with vdW crystals. This strong coupling typically introduces defects during exfoliation, impairing the optoelectronic properties. Herein, we report the liquid-phase exfoliation of few-atomic-layer thin, defect-free, free-standing ZnO nanosheets. These micron-sized, ultrathin ZnO structures exhibit three different orientations aligned along both the polar c-plane as well as the nonpolar a- and m-planes. The superior crystalline quality of the ZnO nanosheets is validated through comprehensive characterization techniques. This result is supported by density functional theory (DFT) calculations, which reveals that the formation of oxygen vacancies is energetically less favorable in 2D ZnO and that the c-plane loses its polarity upon exfoliation. Unlike bulk ZnO, which is typically dominated by defect-induced emission, the exfoliated nanosheets exhibit a strong, ambient-stable excitonic UV emission. We further demonstrate the utility of solution processing of ZnO nanosheets by their hybrid integration with organic components to produce stable light emitting diodes (LEDs) for display applications.

Use of Perfluorochemicals in Li-Air Batteries: A Critical Review.

As lithium-ion (Li-ion) batteries approach their theoretical limits, alternative energy storage systems that can power technology with greater energy demands must be realized. Li-metal batteries, particularly Li-air batteries (LABs), are considered a promising energy storage candidate due to their inherent lightweight and energy-dense properties. Unfortunately, LAB practicality remains hindered by inadequate oxygen solubility and diffusion rates within the electrolyte, both which are fundamental for LAB operation. Due to exceptionally high oxygen solubilities, perfluorochemicals (PFCs) have been investigated as a promising solution to this issue. Although PFCs have been reported to enhance LAB performance and longevity when implemented within the cathodic regions of LABs in several studies, the influence of this class of compounds on other components of the battery (including the anode and the electrolyte) is also highly important. This paper reviews the use of PFCs in LABs to date and discusses the performance enhancements resulting from their implementation. We identify and discuss future prospects and emerging research directions for the use of PFCs into LAB design, in the effort toward realization of high-performing LAB technologies.

Repairing and Preventing Photooxidation of Few-Layer Black Phosphorus with ß-Carotene.

Few-layer black phosphorus (FLBP), a technologically important 2D material, faces a major hurdle to consumer applications: spontaneous degradation under ambient conditions. Blocking the direct exposure of FLBP to the environment has remained the key strategy to enhance its stability, but this can also limit its utility. In this paper, a more ambitious approach to handling FLBP is reported where not only is FLBP oxidation blocked, but it is also repaired postoxidation. Our approach, inspired by nature, employs the antioxidant molecule ß-carotene that protects plants against photooxidative damages to act as a protecting and repairing agent for FLBP. The mechanistic role of ß-carotene is established by a suite of spectro-microscopy techniques, in combination with computational studies and biochemical assays. Transconductance studies on FLBP-based field effect transistor (FET) devices further affirm the protective and reparative effects of ß-carotene. The outcomes indicate the potential for deploying a plethora of natural antioxidant molecules to enhance the stability of other environmentally sensitive inorganic nanomaterials and expedite their translation for technological and consumer applications.

Ferroelectric van der Waals heterostructures of CuInP2S6for non-volatile memory device applications.

Two-dimensional (2D) ferroelectric materials are providing promising platforms for creating future nano- and opto-electronics. Here we propose new hybrid van der Waals heterostructures, in which the 2D ferroelectric material CuInP2S6(CIPS) is layered on a 2D semiconductor for near-infrared (NIR) memory device applications. Using density functional theory, we show that the band gap of the hybrid bilayers formed with CIPS can be tuned and that the optical and electronic properties can be successfully modulated via ferroelectric switching. Of the 3712 heterostructures considered, we identified 19 structures that have a type II band alignment and commensurate lattice matches. Of this set, both the CuInP2S6/PbSe and CuInP2S6/Ge2H2heterostructures possess absorption peaks in the NIR region that change position and intensity with switching polarisation, making them suitable for NIR memory devices. The CuInP2S6/ISSb, CuInP2S6/ISbSe, CuInP2S6/ClSbSe and CuInP2S6/ZnI2heterostructures had band gaps which can be switched from direct to indirect with changing the polarisation of CIPS making them suitable for optoelectronics and sensors. The heterostructures formed with CIPS are exciting candidates for stable ferroelectric devices, opening a pathway for tuning the band alignment of van der Waal heterostructures and the creation of modern memory applications that use less energy.

Improving sensing of formaldehyde using ZnO nanostructures with surface-adsorbed oxygen.

Detection of pollutant gases, such as formaldehyde (HCHO), in our homes and surrounding environment is of high importance for our health and safety. The effect of surface defects and specifically pre-adsorbed oxygen on the gas sensing reaction of HCHO with ZnO nanostructures is largely unknown. Using density functional theory, nonequilibrium Green's function method and ab initio molecular dynamics (AIMD) simulations, we show that the presence of surface oxygen has two key roles in the sensitivity of ZnO towards HCHO: (1) it leads to the presence of charge trap states, which vanish upon the adsorption of HCHO, and (2) it facilitates the dissociative chemisorption of HCHO on the surface. Our ground state and AIMD calculations show that multiple reaction products are produced, which eventually lead to cleaning the surface from the adsorbed species, and hence enhancing the recyclability of the surface. We not only confirm the reaction proposed by experiment, but show that the presence of surface oxygen facilitates other surface reactions as well. Our work provides insights into the gas-surface reaction mechanism of ZnO-nanostructure based gas sensors, not provided before by experiment.

Electric Control of Exchange Bias Effect in FePS3-Fe5GeTe2 van der Waals Heterostructures.

Manipulating the exchange bias (EB) effect using an electronic gate is a significant goal in spintronics. The emergence of van der Waals (vdW) magnetic heterostructures has provided improved means to study interlayer magnetic coupling, but to date, these heterostructures have not exhibited electrical gate-controlled EB effects. Here, we report electrically controllable EB effects in a vdW heterostructure, FePS3-Fe5GeTe2. By applying a solid protonic gate, the EB effects were repeatably electrically tuned. The EB field reaches up to 23% of the coercivity and the blocking temperature ranges from 30 to 60 K under various gate-voltages. The proton intercalations not only tune the average magnetic exchange coupling but also change the antiferromagnetic configurations in the FePS3 layer. These result in a dramatic modulation of the total interface exchange coupling and the resultant EB effects. The study is a significant step toward vdW heterostructure-based magnetic logic for future low-energy electronics.

Electrochemical Stability of Zinc and Copper Surfaces in Protic Ionic Liquids.

Ionic liquids are versatile solvents that can be tailored through modification of the cation and anion species. Relatively little is known about the corrosive properties of protic ionic liquids. In this study, we have explored the corrosion of both zinc and copper within a series of protic ionic liquids consisting of alkylammonium or alkanolammonium cations paired with nitrate or carboxylate anions along with three aprotic imidazolium ionic liquids for comparison. Electrochemical studies revealed that the presence of either carboxylate anions or alkanolammonium cations tend to induce a cathodic shift in the corrosion potential. The effect in copper was similar in magnitude for both cations and anions, while the anion effect was slightly more pronounced than that of the cation in the case of zinc. For copper, the presence of carboxylate anions or alkanolammonium cations led to a notable decrease in corrosion current, whereas an increase was typically observed for zinc. The ionic liquid-metal surface interactions were further explored for select protic ionic liquids on copper using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) to characterize the interface. From these studies, the oxide species formed on the surface were identified, and copper speciation at the surface linked to ionic liquid and potential dependent surface passivation. Density functional theory and ab initio molecular dynamics simulations revealed that the ethanolammonium cation was more strongly bound to the copper surface than the ethylammonium counterpart. In addition, the nitrate anion was more tightly bound than the formate anion. These likely lead to competing effects on the process of corrosion: the tightly bound cations act as a source of passivation, whereas the tightly bound anions facilitate the electrodissolution of the copper.

Tuning the Schottky barrier height in a multiferroic In2Se3/Fe3GeTe2 van der Waals heterojunction.

The ferroelectric material In2Se3 is currently of significant interest due to its built-in polarisation characteristics that can significantly modulate its electronic properties. Here we employ density functional theory to determine the transport characteristics at the metal-semiconductor interface of the two-dimensional multiferroic In2Se3/Fe3GeTe2 heterojunction. We show a significant tuning of the Schottky barrier height as a result of the change in the intrinsic polarisation state of In2Se3: the switching in the electric polarisation of In2Se3 results in the switching of the nature of the Schottky barrier, from being n-type to p-type, and is accompanied by a change in the spin polarisation of the electrons. This switchable Schottky barrier structure can form an essential component in a two-dimensional field effect transistor that can be operated by switching the ferroelectric polarisation, rather than by the application of strain or electric field. The band structure and density of state calculations show that Fe3GeTe2 lends its magnetic and metallic characteristics to the In2Se3 layer, making the In2Se3/Fe3GeTe2 heterojunction a potentially viable multiferroic candidate in nanoelectronic devices like field-effect transistors. Moreover, our findings reveal a transfer of charge carriers from the In2Se3 layer to the Fe3GeTe2 layer, resulting in the formation of an in-built electric field at the metal-semiconductor interface. Our work can substantially broaden the device potential of the In2Se3/Fe3GeTe2 heterojunction in future low-energy electronic devices.

Nicotine Sensors for Wearable Battery-Free Monitoring of Vaping.

Nicotine, an addictive substance in tobacco products and electronic cigarettes (e-cigs), is recognized for increasing the risk of cardiovascular and respiratory disorders. Careful real-time monitoring of nicotine exposure is critical in alleviating the potential health impacts of not just smokers but also those exposed to second-hand and third-hand smoke. Monitoring of nicotine requires suitable sensing material to detect nicotine selectively and testing under free-living conditions in the standard environment. Here, we experimentally demonstrate a vanadium dioxide (VO2)-based nicotine sensor and explain its conductometric mechanisms with compositional analysis and density functional theory (DFT) calculations. For real-time monitoring of nicotine vapor from e-cigarettes in the air, the sensor is integrated with an epidermal near-field communication (NFC) interface that enables battery-free operation and data transmission to smart electronic devices to record and store sensor data. Collectively, the technique of sensor development and integration expands the use of wearable electronics for real-time monitoring of hazardous elements in the environment and biosignals wirelessly.

Surface Functionalization of WS2 Nanosheets with Alkyl Chains for Enhancement of Dispersion Stability and Tribological Properties.

Tungsten disulfide (WS2) exhibits intriguing tribological properties and has been explored as an excellent lubricious material in thin-film and solid lubricants. However, the poor dispersibility of WS2 has been a major challenge for its utilization in liquid lubricant applications. Herein, a top-down integrated approach is presented to synthesize oxygenated WS2 (WS2-O) nanosheets via strong acid-mediated oxidation and ultrasound-assisted exfoliation. The ultrathin sheets of WS2-O, comprising 4-7 molecular lamellae, exhibit oxygen/hydroxyl functionalities. The organosilanes having variable surface-active leaving groups (chloro and ethoxy) are covalently grafted, targeting the hydroxyl/oxygen functionalities on the surface of WS2-O nanosheets. The grafting of organosilanes is governed by the reactivity of chloro and ethoxy leaving groups. The DFT calculations further support the covalent interaction between the WS2-O nanosheets and organosilanes. The alkyl chain-functionalized WS2-O nanosheets displayed excellent dispersibility in mineral lube base oil. A minute dose of chemically functionalized-WS2 (0.2 mg.mL-1) notably enhanced the tribological properties of mineral lube oil by reducing the friction coefficient (52%) and wear volume (79%) for a steel tribopair. Raman analysis of worn surfaces revealed WS2-derived lubricious thin film formation. The improved tribological properties are attributed to ultralow thickness, stable dispersion, and low shear strength of chemically functionalized WS2 nanosheets, along with protective thin film formation over the contact interfaces of a steel tribopair. The present work opens a new avenue toward exploiting low-dimensional nanosheets for minimizing energy losses due to high friction.

Zero valence iron nanocube decoration of graphitic nanoplatelets.

Graphitic nanoplatelets (GNPs) have been treated using an ultrasonicated ozonolysis procedure to produce stable aqueous dispersions that facilitate deposition of thin films using electrophoretic deposition. The thin GNP films were then coated with zero valence (ZV) iron nanocubes using a pulsed electrodeposition technique. Characterization of the ZV-iron coating with deposition time revealed that the changing magnetic character of the ferromagnetic-graphitic hybrid material was related to the nucleation density and growth of the ZV-iron nanocubes. Density functional theory calculations show a preference for ZV-iron adsorption at the oxygen sites of the GNPs, with ZV-iron displacement of oxygen groups favored in some configurations. Transmission electron microscopy studies confirm ZV-iron growth nucleates preferentially at the graphite nanoplatelet edges and the hybrid material magnetism is affected by the convergent crystalline grain boundaries formed between adjacent ZV-iron nanocubes.

Fluorinated Boron-Based Anions for Higher Voltage Li Metal Battery Electrolytes.

Lithium metal batteries (LMBs) require an electrolyte with high ionic conductivity as well as high thermal and electrochemical stability that can maintain a stable solid electrolyte interphase (SEI) layer on the lithium metal anode surface. The borate anions tetrakis(trifluoromethyl)borate ([B(CF3)4]-), pentafluoroethyltrifluoroborate ([(C2F5)BF3]-), and pentafluoroethyldifluorocyanoborate ([(C2F5)BF2(CN)]-) have shown excellent physicochemical properties and electrochemical stability windows; however, the suitability of these anions as high-voltage LMB electrolytes components that can stabilise the Li anode is yet to be determined. In this work, density functional theory calculations show high reductive stability limits and low anion-cation interaction strengths for Li[B(CF3)4], Li[(C2F5)BF3], and Li[(C2F5)BF2(CN)] that surpass popular sulfonamide salts. Specifically, Li[B(CF3)4] has a calculated oxidative stability limit of 7.12 V vs. Li+/Li0 which is significantly higher than the other borate and sulfonamide salts (≤6.41 V vs. Li+/Li0). Using ab initio molecular dynamics simulations, this study is the first to show that these borate anions can form an advantageous LiF-rich SEI layer on the Li anode at room (298 K) and elevated (358 K) temperatures. The interaction of the borate anions, particularly [B(CF3)4]-, with the Li+ and Li anode, suggests they are suitable inclusions in high-voltage LMB electrolytes that can stabilise the Li anode surface and provide enhanced ionic conductivity.

Spectroscopic and Computational Study of Boronium Ionic Liquids and Electrolytes.

Boronium cation-based ionic liquids (ILs) have demonstrated high thermal stability and a >5.8 V electrochemical stability window. Additionally, IL-based electrolytes containing the salt LiTFSI have shown stable cycling against the Li metal anode, the "Holy grail" of rechargeable lithium batteries. However, the basic spectroscopic characterisation needed for further development and effective application is missing for these promising ILs and electrolytes. In this work, attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy and density functional theory (DFT) calculations are used in combination to characterise four ILs and electrolytes based on the [NNBH2 ]+ and [(TMEDA)BH2 ]+ boronium cations and the [FSI]- and [TFSI]- anions. By using this combined experimental and computational approach, proper understanding of the role of different ion-ion interactions for the Li cation coordination environment in the electrolytes was achieved. Furthermore, the calculated vibrational frequencies assisted in the proper mode assignments for the ILs and in providing insights into the spectroscopic features expected at the interface created when they are adsorbed on a Li(001) surface. A reproducible synthesis procedure for [(TMEDA)BH2 ]+ is also reported. The fundamental findings presented in this work are beneficial for any future studies that utilise IL based electrolytes in next generation Li metal batteries.

Broad-Spectrum Solvent-free Layered Black Phosphorus as a Rapid Action Antimicrobial.

Antimicrobial resistance has rendered many conventional therapeutic measures, such as antibiotics, ineffective. This makes the treatment of infections from pathogenic micro-organisms a major growing health, social, and economic challenge. Recently, nanomaterials, including two-dimensional (2D) materials, have attracted scientific interest as potential antimicrobial agents. Many of these studies, however, rely on the input of activation energy and lack real-world utility. In this work, we present the broad-spectrum antimicrobial activity of few-layered black phosphorus (BP) at nanogram concentrations. This property arises from the unique ability of layered BP to produce reactive oxygen species, which we harness to create this unique functionality. BP is shown to be highly antimicrobial toward susceptible and resistant bacteria and fungal species. To establish cytotoxicity with mammalian cells, we showed that both L929 mouse and BJ-5TA human fibroblasts were metabolically unaffected by the presence of BP. Finally, we demonstrate the practical utility of this approach, whereby medically relevant surfaces are imparted with antimicrobial properties via functionalization with few-layer BP. Given the self-degrading properties of BP, this study demonstrates a viable and practical pathway for the deployment of novel low-dimensional materials as antimicrobial agents without compromising the composition or nature of the coated substrate.

Fully Light-Controlled Memory and Neuromorphic Computation in Layered Black Phosphorus.

Imprinting vision as memory is a core attribute of human cognitive learning. Fundamental to artificial intelligence systems are bioinspired neuromorphic vision components for the visible and invisible segments of the electromagnetic spectrum. Realization of a single imaging unit with a combination of in-built memory and signal processing capability is imperative to deploy efficient brain-like vision systems. However, the lack of a platform that can be fully controlled by light without the need to apply alternating polarity electric signals has hampered this technological advance. Here, a neuromorphic imaging element based on a fully light-modulated 2D semiconductor in a simple reconfigurable phototransistor structure is presented. This standalone device exhibits inherent characteristics that enable neuromorphic image pre-processing and recognition. Fundamentally, the unique photoresponse induced by oxidation-related defects in 2D black phosphorus (BP) is exploited to achieve visual memory, wavelength-selective multibit programming, and erasing functions, which allow in-pixel image pre-processing. Furthermore, all-optically driven neuromorphic computation is demonstrated by machine learning to classify numbers and recognize images with an accuracy of over 90%. The devices provide a promising approach toward neurorobotics, human-machine interaction technologies, and scalable bionic systems with visual data storage/buffering and processing.

Liquid-Metal Synthesized Ultrathin SnS Layers for High-Performance Broadband Photodetectors.

Atomically thin materials face an ongoing challenge of scalability, hampering practical deployment despite their fascinating properties. Tin monosulfide (SnS), a low-cost, naturally abundant layered material with a tunable bandgap, displays properties of superior carrier mobility and large absorption coefficient at atomic thicknesses, making it attractive for electronics and optoelectronics. However, the lack of successful synthesis techniques to prepare large-area and stoichiometric atomically thin SnS layers (mainly due to the strong interlayer interactions) has prevented exploration of these properties for versatile applications. Here, SnS layers are printed with thicknesses varying from a single unit cell (0.8 nm) to multiple stacked unit cells (≈1.8 nm) synthesized from metallic liquid tin, with lateral dimensions on the millimeter scale. It is reveal that these large-area SnS layers exhibit a broadband spectral response ranging from deep-ultraviolet (UV) to near-infrared (NIR) wavelengths (i.e., 280-850 nm) with fast photodetection capabilities. For single-unit-cell-thick layered SnS, the photodetectors show upto three orders of magnitude higher responsivity (927 A W-1 ) than commercial photodetectors at a room-temperature operating wavelength of 660 nm. This study opens a new pathway to synthesize reproduceable nanosheets of large lateral sizes for broadband, high-performance photodetectors. It also provides important technological implications for scalable applications in integrated optoelectronic circuits, sensing, and biomedical imaging.

Structural-Defect-Mediated Grafting of Alkylamine on Few-Layer MoS2 and Its Potential for Enhancement of Tribological Properties.

Two-dimensional transition-metal dichalcogenides possess inherent structural characteristics that can be harnessed for enhancement of tribological properties by making them dispersible in lube media. Here, we present a hydrothermal approach to preparing MoS2 nanosheets comprising 4-10 molecular lamellae. A structural-defect-mediated route for grafting of octadecylamine (ODA) on MoS2 nanosheets is outlined. The unsaturated d orbitals of Mo at the sulfur vacancies on the MoS2 surface are coupled with the electron-rich nitrogen center of ODA and yield ODA-functionalized MoS2 (MoS2-ODA). The MoS2-ODA nanosheets exhibit good dispersibility in lube base oil and are used as an additive (optimized dose: 0.1 mg·mL-1) to mineral oil. It is shown that even at low concentration, MoS2-ODA nanosheets significantly reduce the friction (48%) and wear (44%). Microscopy (field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM)) and spectroscopy (Raman and elemental mapping) analyses of worn scars revealed the formation of MoS2-based protective thin films for lowering of friction and wear. This work, therefore, presents a pathway for low-friction lubricants by deploying functionalized low-dimensional material systems.

Electrically Activated UV-A Filters Based on Electrochromic MoO3-x.

Chromism-based optical filters is a niche field of research, due to there being only a handful of electrochromic materials. Typically, electrochromic transition metal oxides such as MoO3 and WO3 are utilized in applications such as smart windows and electrochromic devices (ECD). Herein, we report MoO3-x-based electrically activated ultraviolet (UV) filters. The MoO3-x grown on indium tin oxide (ITO) substrate is mechanically assembled onto an electrically activated proton exchange membrane. Reversible H+ injection/extraction in MoO3-x is employed to switch the optical transmittance, enabling an electrically activated optical filter. The devices exhibit broadband transmission modulation (325-800 nm), with a peak of ∼60% in the UV-A range (350-392 nm). Comparable switching times of 8 s and a coloration efficiency of up to 116 cm2 C-1 are achieved.

Development of Stable Boron Nitride Nanotube and Hexagonal Boron Nitride Dispersions for Electrophoretic Deposition.

Boron nitride nanotubes (BNNTs) represent a relatively new class of materials that provides alternative electrical and thermal properties to the carbon analogue. The high chemical and thermal stability and large band gap combined with high electrical resistance make BNNTs desirable in several thin-film applications. In this study, stable BNNT and hexagonal boron nitride (hBN) particle dispersions have been developed using environmentally friendly advanced oxidation processing (AOP) that can be further modified for electrophoretic deposition (EPD) to produce thin films. The characterization of the dispersions has revealed how the hydroxyl radicals produced in AOP react with BNNT/hBN and contaminant boron nanoparticles (BNPs). While the radicals remove the carbon contaminant present on BNNT/hBN and increase dispersion stability, they also oxidize the BNPs and the boron oxide produced, which, conversely, reduces the dispersion stability. The use of high- or low-powered ultrasonication in combination with the AOP affects the rate of the competing reactions, with low-powered sonication and AOP providing the best combination for producing stable dispersions with high concentrations. BNNT/hBN dispersions were functionalized with polyethyleneimine to facilitate EPD, where films of several micrometer thickness were readily deposited onto stainless steel and glass-fiber fabrics. BNNT/hBN films produced on glass fabrics by EPD exhibited a consistent through-thickness macroporosity that was facilitated by platelet and nanotube stacking. The film macroporosity present on the coated fabrics was suitable for use as separator layers in supercapacitors and provided improved device robustness with a minimal impact on electrochemical performance.