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Herein, a model is proposed for measuring the structural defects size r0 in an ultrathin magnetic layer with perpendicular magnetic anisotropy. Based on the observations of magnetic domains in Ta/Pt/Co/Pt ultrathin films, using polar magneto‐optical Kerr effect microscopy and measurements of their magnetic anisotropies, the correlation between magnetic domains size D and structural defects size r0, as well as the defects concentration parameter αK, which designates the degree of pinning, has been modeled. The average r0 value found is high in the sample with unannealed buffer layers and considerably decreases with annealing. It is 6.17 nm with unannealed Ta/Pt buffer layers, 1.06 nm in sample with Ta/Pt buffer layers annealed at 423 K, and 0.49 nm in that with buffer layers annealed at 573 K. The significant drop of r0 is in good agreement with the high depinning noted with buffer layers annealing in recent work. [ABSTRACT FROM AUTHOR]

Self‐powered UV sensing has enormous potential in military and civilian applications. However, achieving high responsivity and fast response/recovery time presents significant challenges. Self‐powered photodetectors (PDs) have several advantages over traditional PDs, including higher sensitivity, lower power consumption, and simpler design. This study introduces a breakthrough self‐powered PD that uses a Schottky junction of 2D α‐MoO3/iridium (Ir)/Si ultrathin film to detect 365 nm light at 0 V bias through using atomic layer deposition (ALD) and sputtering systems. The PD response is enhanced by plasmonic Ir‐induced hot carriers, enabling detection in a mere 0.1 ms. Incorporating a 4 nm Ir layer boosts the responsivity from 0 to 34 A W−1, and the external quantum efficiency is elevated from 0 to 7E11 under 365 nm light illumination. It also has a high ION/IOFF ratio of 11.22E4 at 0 V. These results make the MoO3/4 nm Ir/Si structure an interesting option for self‐powered PDs with high efficiency, and the use of a simple ALD system for large‐scale fabrication of 2D α‐MoO3 on hot carrier Ir plasmonic layer. The findings of this research hold tremendous promise in the field of UV sensing and can lead to exciting developments in military and civilian technology. [ABSTRACT FROM AUTHOR]

One of the unsolved problems for using high‐Tc superconducting cuprates for spintronic applications are the short coherence lengths of Cooper pairs in oxides (a few Å), which requires atomically sharp and defect‐free interfaces. This research demonstrates the presence of high‐Tc superconducting La1.84Sr0.16CuO4 in direct proximity to SrLaMnO4 and provides evidence for the sharpness of interfaces between the cuprate and the manganite layers at the atomic scale. These findings shed light on the impact of the chemical potential at the interface of distinct materials on highly sensitive physical properties, such as superconductivity. Additionally, this results show the high stability of ultrathin layers from the same K2NiF4‐type family, specifically one unit cell of Sr2−xLaxMnO4 and three unit cells of La1.84Sr0.16CuO4. This work advances both the fundamental understanding of the proximity region between superconducting cuprates and manganite phases and the potential use of oxide‐based materials in quantum computing. [ABSTRACT FROM AUTHOR]

In a previous report, 25 Å periodic metal–insulator transitions dependent on the thickness of CaRuO3 ultrathin films were discovered. Compared to the conventional size effect caused by quantum wells, the rate of change is a few billions of times greater at low temperatures. Although the electrical resistivity of insulating state differs by several orders with the film thickness, the enhancement trigger was not clarified. In this study, it is clarified that the magnitude of the extraordinary size effect varies with the element supply ratio owing to precise control of the molecular beam rates of calcium and ruthenium. The supplied calcium over ruthenium ratio Ca/Ru = 1.2–1.8 during CaRuO3 deposition results in a stoichiometric ratio of Ca:Ru = 1:1 on the CaRuO3 films. Calcium‐rich elemental supply conditions result in large electrical resistivity variations. Electrical resistivity oscillations with periods of T = 23.4 and 26.3 Å are observed for the growth conditions of Ca/Ru = 1.2 and 1.6, respectively. Furthermore, a flat surface with a roughness of ≈2 Å is required to observe the size effect. Thus, the insulation of an extraordinary size effect is enhanced in CaRuO3 ultrathin films grown under the condition of calcium‐rich Ca/Ru ≈ 1.6. [ABSTRACT FROM AUTHOR]

Harvesting sustainable energy opens new avenues for powering portable electronic devices using triboelectric nanogenerators (TENGs). Synthetic metals and polymers are used to construct most of the TENGs. Hence, ultrathin, free‐standing, translucent, and chemically bonded chitosan (CH)‐ and alginate (AL)‐based biopolymeric films are introduced here. These films are fabricated using a low‐cost and environmentally friendly layer‐by‐layer (LbL) self‐assembly method and impregnated with AgNO3 (S) in the final fabrication step (denoted as [(CH/AL)n:(CHS/AL)1]n+1). The LbL‐assembled film displays remarkable antimicrobial and triboelectric properties, demonstrating a new type of TENG that is implantable in the body. By varying the number of CH and AL depositions, the dependence of TENG behaviors on thickness is investigated. It is demonstrated that a 0.87‐µm‐thick [CH/AL]8 TENG resulted in the highest electrical output performance of 474 V and 36.9 mA m−2 due to the highest surface potential and the lowest work function of 239.4 mV and 4.2 eV, respectively. A free‐standing [(CH/AL)49:(CHS/AL)1]50 TENG is designed for antimicrobial skin‐patchable shape‐adaptive nanogenerators, displaying ultrahigh translucency, long‐term mechanical stability, and exceptional versatility. It is then attached to the arm to detect external stimuli, and the feasibility of its use as an encodable skin‐touch sensor is demonstrated. [ABSTRACT FROM AUTHOR]

This study reports the first fully additively manufactured capacitors as a proof‐of‐concept demonstration of direct‐write, ultrathin‐film electronic components made via multi‐material microplasma sputtering. This is also the first demonstration of a cleanroom‐quality, multi‐material electrical device produced entirely through additive manufacturing. Ultrathin metal and dielectric films are deposited at <80 °C and atmospheric pressure conditions on a substrate using a novel, continuously fed, dual target microsputtering printhead. The conductive films are created by sputtering gold in an air atmosphere and shown to attain near‐bulk electrical resistivity. The dielectric films are created by sputtering aluminum in a gas blend of argon and air; the aluminum oxidizes in the high‐energy, high‐collisionality plasma, forming alumina nanoparticles that are deposited on the substrate. Ultra‐thin (35 nm) alumina films showed extremely high resistivity (100 GΩ‐m) and dielectric strength (6.2 GV m−1). Also, the frequency response of the capacitor is satisfactorily described by the universal dielectric response typically found in heterogenous dielectrics. It is hypothesized that the dielectric response is the result of the presence of condensed water in the pores of the alumina film. [ABSTRACT FROM AUTHOR]

In this work, simple and cost‐effective phyiscal vapor deposition method is applied for deposition of single Bi2Se3, Bi1.925Sn0.075Se3, Bi2Se2.975Te0.025 ultrathin films of average thickness 10–12 nm, and for the fabrication of n‐type 5‐layer nanolaminates. The nanolaminates are composed from alternating doped and undoped ultrathin films. Electrical and thermoelectric properties (Seebeck coefficient, resistivity, electron thermal conductivity, charge carrier concentration, and mobility) of nanolaminates as well as single ultrathin undoped and doped films are studied at room temperature under ambient conditions. Both types of nanolaminates show 75–125% increase of the Seebeck coefficient accompanied by the 65–85% reduction of the electron thermal conductivity in comparison with the nanostructured bulk materials of similar chemical compositions. The mechanisms underlying such improvement of properties of studied nanolaminates in comparison with the nanostructured bulk counterparts are discussed. [ABSTRACT FROM AUTHOR]

Herein, the crystalline and electronic structures of ultrathin cadmium sulfide {0001} films with thickness ranging from 1 to 14 Cd–S bilayers are studied using first‐principles calculations method. After structural relaxation, the film composed of 1 Cd–S bilayer is transformed into a CdS monolayer with flat honeycomb structure. Those 2‐ to 5‐bilayer films do not maintain the Wurtzite structure either: the distance between the sulfur and cadmium layers in each bilayer is compressed while the Cd–S bond length between adjacent bilayers is enlarged. These 1‐ to 5‐bilayer films reveal semiconducting characteristics in band structures, and their bandgaps are widened in some degree compared with the bulk. The films with 6–14 Cd–S bilayers keep the Wurtzite structure of the bulk, and exhibit metallic surface states due to the polarity of the films. The results could provide a new insight for the electronic structure regulation of cadmium sulfide. [ABSTRACT FROM AUTHOR]

Perovskite solar cells have potential to deliver terawatt‐scale power via low‐cost manufacturing. However, scaling is limited by slow, high‐temperature annealing of the inorganic transport layers and the lack of reliable, large‐area methods for depositing thin (<30 nm) charge transport layers (CTLs). We present a method for scaling ultrathin NiOx hole transport layers (HTLs) by pairing high‐speed (60 m min−1) flexographic printing with rapidly annealed sol–gel inks to achieve the fastest reported process for fabrication of inorganic CTLs for perovskites. By engineering precursor rheology for rapid film‐leveling, NiOx HTLs were printed with high uniformity and ultralow pinhole densities resulting in photovoltaic performance exceeding that of spin‐coated devices. Integrating these printed transport layers in planar inverted PSCs allows rapid fabrication of high‐efficiency (PCE > 15%) CsxFA1−xPbI solar cells with improved short circuit currents (Jsc) of 22.4 mA cm−2. Rapid annealing of the HTL accelerates total processing time by 60X, while maintaining the required balance of optoelectronic properties and the chemical composition for effective hole collection. These results build an improved understanding of ultrathin NiOx and reveal opportunities to enhance device performance via scalable manufacturing of inorganic CTLs. [ABSTRACT FROM AUTHOR]

The crystalline component and crystallization morphology of poly(vinylidene fluoride‐chlorotrifluoroethylene) (P(VDF‐CTFE)) ultrathin film have been investigated. The CTFE segment has been characterized as the crystal composition of the film. For the film on the Si substrate, the nucleation behavior is dominated by homogeneous nucleation to form edge‐on lamellae in the initial stage of crystal nucleation growth. The edge‐on lamella will continue to grow at high crystallization temperature (Tc). However, it will be transformed into flat‐on lamellae at low Tc. For the film on Au substrate, the primary nucleation rate of the layer near the film surface has a competitive relationship when compared with the primary nucleation rate of the layer near the film/substrate interface. The nucleation behavior is preferentially dominated by heterogeneous nucleation to form flat‐on lamellae at high Tc. But it is conducive to homogeneous nucleation to form edge‐on lamellae at low Tc. Further investigation suggests that the different crystalline morphologies of P(VDF‐CTFE) ultrathin film obtained on Au and Si surfaces are closely related to the different interface effects between the film and the substrates. It is anticipated that this study will cast new light on the rational regulation of the morphologies of ultrathin films. [ABSTRACT FROM AUTHOR]

Ultrathin, transparent, and free‐standing films assembled from low‐dimensional nanomaterials (LDMs) are promising for various applications, including transparent heaters and membranes. However, the intact separation of the assembled films, especially those with controlled ultrathin thickness from deposited substrates, is a tremendous challenge, particularly for fast peeling off via self‐detaching. Herein, we propose a versatile method to rapidly peel off ultrathin assembled LDM films, including three types of carbon nanotubes, vermiculite, Ag nanowires, and carbon nanotube@graphene, by dissolving the MXene interlayer from the layer‐by‐layer filtered MXene/LDM Janus films using diluted H2O2. The MXene sacrificial interlayers play dual roles, including physical isolation of LDM films from filter membranes and the production of bubbles that buoy ultrathin LDM films, making them free‐standing. The integrality and self‐detaching rate of the LDM films are determined by the loading and reactivity of the MXene interlayers. The intact LDM films can self‐detach in 80 s by dissolving the optimized MXene interlayer and producing bubbles. The as‐made free‐standing ultrathin LDM films can be transferred to arbitrary substrates and exhibit outstanding performance as transparent heaters. This scalable method provides an efficient and versatile method to produce ultrathin, transparent, and free‐standing LDM films and finds new applications for the growing MXene family. [ABSTRACT FROM AUTHOR]

Thermal camouflage has attracted increasing attention owing to the rapid development of infrared (IR) surveillance technologies. Various materials and systems have been developed to date, but the realization of high‐temperature thermal camouflage using ultrathin film/coating remains a great challenge; this is of great significance, especially for IR stealth in military equipment. This work demonstrates a series of ultrathin Ti3C2Tx MXene films (as low as 1 µm) with superior high‐temperature indoor/outdoor thermal camouflage performance: wide camouflage temperature range (from below −10 °C to over 500 °C), large reduction in radiation temperature (exceeding 300 °C for objects with temperatures over 500 °C), long‐term high‐temperature or fire stability, multifunctionality including disguised Joule heating capability, and high electromagnetic interference shielding efficiency. The superior high‐temperature thermal camouflage performance of the ultrathin MXene film is attributed to its low mid‐IR emissivity (0.19), which is comparable to that of stainless steel but far below that of other 2D nanomaterials, such as graphene. The multifunctional ultrathin MXene films prepared through simple vacuum‐assisted filtration provide a feasible method for efficient high‐temperature thermal camouflage using ultrathin films, demonstrating the great promise of MXene materials for thermal camouflage, IR stealth, counter‐surveillance, and security protection. [ABSTRACT FROM AUTHOR]

Despite significant progresses in development of superhydrohpobic coatings, their ability to resist small water droplets, which can exert large Laplace pressure on surface, remain limited. Here, a new strategy by self‐assembly of a monolayer of chained silica nanoparticles, forming an ultrathin film (<100 nm) with two‐tiered nanoasperity is presented. The resulting coating shows ultrahigh water repellency and high visible transparency. It can also repel low surface energy liquids, such as alcohol/water mixtures (surface tension ≥42 mN m−1). Importantly, the superhydrophobic coating demonstrates high resistance to impact pressure (at least 250 Pa) from water droplets dropped from 3.3 m height and internal Laplace pressure of 15 kPa from evaporated water droplets. Furthermore, the CNP coating remains to be superhydrophobic with condensed water droplets radius as small as 0.3 mm even after condensation for 6 h. In comparison, all of these properties are not possible from the assembly of spherical nanoparticles. [ABSTRACT FROM AUTHOR]

Graphdiyne (GDY) has been ideal candidate support for atomic catalysts (ACs) due to its unique conjugated two‐dimensional (2D) structure comprising both sp‐ and sp2‐hybrid carbon atoms. ACs/GDY can display excellent catalytic ability and high selectivity, emerging as a cutting‐edge research area in the past few years. Recently, a growing body of work has been done in ACs/GDY, ranging from screening appropriate combinations theoretically, continuous improvement to prepare few‐layered GDY to meet the critical challenge in this area, and successfully fabricating ACs/GDY in facile way. This Minireview briefly introduces recent advanced progress in this field, including the synthetic method for both thin GDY film and ACs/GDY, as well as theoretical analysis of different ACs/GDY systems, characterization, and applications. In the end, the challenges and further opportunities of ACs/GDY are summarized and proposed. It is hoped that this article brings new insights into the current study of ACs/GDY and promotes better development in this area. [ABSTRACT FROM AUTHOR]

Low‐dimensional structures comprised of ferroelectric (FE) PbTiO3 (PTO) and quantum paraelectric SrTiO3 (STO) are hosts to complex polarization textures such as polar waves, flux‐closure domains, and polar skyrmion phases. Density functional theory (DFT) simulations can provide insight into this order, but are limited by the computational effort required. Within DFT, the novel multi‐site support function method is used to reduce the solution time for the electronic groundstate whilst preserving high accuracy. This allows for large‐scale simulations of PTO films on STO substrates with system sizes >2000 atoms. In the ultrathin limit, the polar wave texture with cylindrical chiral bubbles emerges as an intermediate phase between full‐flux‐closure domains and in‐plane polarization. This is driven by an internal bias field born of the compositionally broken inversion symmetry in the [001] direction. Manipulation of this built‐in field informs a new principle of design for control over chiral order on the nanoscale through the careful choice of substrate, surface termination, or use of overlayers. Antiferrodistortive (AFD) order locally interacts with these polar textures giving rise to strong FE/AFD coupling at the PbO terminated surface driving a p(2×Λ) surface reconstruction. This offers another pathway for the local control of ferroelectricity. [ABSTRACT FROM AUTHOR]

To optimize the catalytic functionality of cerium oxide it is important to understand the structural modifications associated with reduction and the role of the proximity of metals, which are often coupled with the oxide in the applications. For this purpose, the evolution of the short‐ and long‐range structure of cerium oxide ultrathin epitaxial films and nanostructures supported on Pt(111) is investigated using X‐ray absorption spectroscopy at the Ce L3 edge and surface X‐ray diffraction, during reduction by thermal treatments in vacuum. In epitaxial nanoislands reduction is associated with a contraction of the Ce–O distance and with the appearance of CePt bonds. The formation of a phase with a (2 × 2) periodicity after a thermal treatment at 1023 K is ascribed to the formation of a Pt5Ce alloy. Films of 3 nm thickness do not show, on average, significant structural modifications with the same thermal treatment, consistent with the hypothesis that the reduction involves only the topmost surface layers and it does not influence significantly the bulk structure of the material. This study demonstrates a strong interaction between cerium oxide and platinum, which has implications for the reactivity and stability of catalysts based on metals combined with reducible oxides. [ABSTRACT FROM AUTHOR]

Whether intentional or unintentional, thin dielectric interlayers can be found in technologies ranging from catalysis to organic electronics. While originally considered as passive decoupling layers, recently it has been shown that they can actively promote charge transfer from the underlying metal to adsorbates. This charging can have profound effects on the surface chemistry of atoms, atomic clusters, and molecules, their magnetic moments, and charge injection at the contacts of organic devices. Yet, controlled studies required to understand the charge transfer process in depth are still lacking. Here, a comprehensive analysis of the phenomenon of charge transfer using the atomically controlled system of pentacene on ultrathin MgO(100) films on Ag(100) is presented. It is shown that the charge transfer process is governed by the charged and uncharged molecular species with distinct energy levels in the first monolayer. The experimental approach applied in this work allows to observe and control their ratio through direct tuning of either the work function or the thickness of the dielectric interlayer. [ABSTRACT FROM AUTHOR]

Ultrathin molecular films can be used as building blocks to enable rational design of functionalities at the molecular level. A versatile and scalable approach to fabricate transfer‐compatible ultrathin molecular films with a broad range of physiochemical properties is reported. Different molecules in layers of uniform nanoscale thickness are deposited on monolayer hexagonal boron nitride (ML h‐BN) film. Initially, the deposited molecules form islands due to limited molecular diffusion during deposition on ML h‐BN, but postannealing effectively transforms them to the thermodynamically preferred film structures. Ultrathin building blocks composed of ML h‐BN and different molecules (C60, pentacene, C44H32N2) are realized, then transferred layer‐by‐layer (L‐by‐L) to form materials with precisely controlled composition and thickness, including donor/acceptor superlattices. This approach can facilitate the integration of nanoscale molecules with different material platforms for advanced functionalities. [ABSTRACT FROM AUTHOR]

Conductive hydrogels show promising applications in wearable electronic devices. However, it is still challenging to increase the conductivity as well as the mechanical performance of the conductive hydrogels. In addition, it is more challenging to fabricate ultrathin conductive films with good mechanical strength and high transparency. In this study, a metal‐free flexible conductive hydrogel for flexible wearable strain sensor with high sensitivity is presented. The conductive hydrogel is prepared by polyvinyl alcohol (PVA) templated polymerizing of polypyrrole (PPy) followed by gelating based on the polymerizing and cross‐linking of polyacrylamide (PAAm). The conductive hydrogel is endowed excellent mechanical properties by multiple hydrogen bonds between the interpenetrating network of PVA, PPy, and PAAm. The tensile strength reaches up to 0.2 MPa at 500% and the compression strength reaches up to 1.5 MPa at 90%. It can withstand cyclic loads. The conductivity reaches 0.3 s m−1 and it is sensitive to stretching and compressing. Therefore, strain sensors are prepared based on such hydrogels to make wearable electronic devices, monitoring the subtle and large strains. It is worth noting that the composite material containing PVA has good film‐forming properties. Therefore, ultrathin conductive hydrogel films with high transparency (94.2%), high conductivity (7090 Ω/square) and large‐area are fabricated at low cost. [ABSTRACT FROM AUTHOR]

Currently, an urgent task related to creating a nuclear frequency standard is the identification of a low‐lying nuclear state in the thorium‐229 isotope. Herein, a method for measuring the single‐photon energy during the decay of an isomeric thorium‐229 nucleus implanted in a wide‐gap dielectric SiO2 (Eg = 9 eV) is developed. The proposed method utilizes thin silicon oxide layers obtained by thermal oxidization of the pure silica wafers, which allows measurement of the energy of photons in the ultraviolet (UV) range using an electronic spectrometer. The modeling study of electronic state excitation is provided via UV radiation from Kr, Xe, and D resonance discharging lamps. The obtained spectra are analyzed, and a method for determining the UV photon's energy is proposed. [ABSTRACT FROM AUTHOR]

Conductive metal–organic frameworks are opening new perspectives for the use of these porous materials for applications traditionally limited to more classical inorganic materials, such as their integration into electronic devices. This has enabled the development of chemiresistive sensors capable of transducing the presence of specific guests into an electrical response with good selectivity and sensitivity. By combining experimental data with computational modelling, a possible origin for the underlying mechanism of this phenomenon in ultrathin films (ca. 30 nm) of Cu‐CAT‐1 is described. Electrical response to atmospheric guests: Experimental data were combined with computational modeling to describe a possible origin for the underlying mechanism of the direct dependence of the electrical response with MOF–guest interaction phenomena in ultrathin films (ca. 30 nm) of Cu‐CAT‐1. [ABSTRACT FROM AUTHOR]

Abstract: Stretchability plays an important role in wearable devices. Repeated stretching often causes the conductivity dramatically decreasing due to the damage of the inner conductive layer, which is a fatal and undesirable issue in this field. Herein, a convenient rolling strategy to prepare conductive fibers with high stretchability based on a spiral structure is proposed. With the simple rolling design, low resistance change can be obtained due to confined elongation nof the gold thin‐film cracks, which is caused by the encapsulated effect in such a structure. When the fiber is under 50% strain, the resistance change (R/R0) is about 1.5, which is much lower than a thin film at the same strain (R/R0 ≈ 10). The fiber can even afford a high load strain (up to 100%), but still retain good conductivity. Such a design further demonstrates its capability when it is used as a conductor to confirm signal transfer with low attenuation, which can also be woven into textile to fabricate wearable electronics. [ABSTRACT FROM AUTHOR]

The potential of porphyrin-derived metal organic covalent networks (OCN) thin films on light gas separations has been recently demonstrated. However, whether or not the central metal ion of the porphyrin plays a key role on separation performance has yet to be elucidated. Here, one metal-free and three metal-containing (zinc(II), manganese(III), and cobalt(II)) porphyrin-derived OCN thin films are successfully deposited on various substrates via an easily scalable initiated plasma-enhanced chemical vapor deposition approach. Among these four porphyrin-derived OCN thin films exhibiting superior light gas separation performances, three of them are synthesized for the first time. The gas permeation properties of these four OCN thin films suggest that the central metal ions neither significantly alter the packing structure of resulting OCN thin films, nor introduce facilitated transport phenomena favoring oxygen transmission. This observation is further validated by density functional theory calculations. Additional aging tests are also carried out to evaluate the physical aging behavior of the OCN thin films. [ABSTRACT FROM AUTHOR]

Interface modification is a heavily investigated method of extending the lifetime of lithium ion batteries. While many studies have explored the effect of interface coating on the lifetime, the rate capability is often overlooked. In this study, the authors investigated the influence of ultrathin (<10 nm) atomic layer deposition (ALD) coatings of amorphous Al2O3 and amorphous TiO2. It is found that, on thin-film anatase TiO2, the rate capability is unaffected by an amorphous TiO2 coating since it does not pose an additional impedance on the system, while Al2O3 coatings are detrimental for the rate performance due to the 1.5 × 1012 Ω cm resistivity toward lithium ions. A thicker than 2 nm ALD Al2O3 film is found to block lithium transfer completely, resulting in a purely capacitive film. Solvent oxidation is studied on thin-film LiMn2O4. The authors demonstrate that both coatings can partially solve the solvent decomposition. However, the kinetic bottleneck posed by 1 nm Al2O3 is still greater than the uncoated LiMn2O4, leading to worsened rate capability. ALD TiO2 on the other hand can prevent most of the solvent decomposition, resulting in smoother electrodes. The absence of the decomposition layer and lithium conducting properties of the ALD TiO2 films results in an improved rate capability for the ALD TiO2 coated electrode. [ABSTRACT FROM AUTHOR]

We describe the implementation of an experimental setup based on Surface Enhanced Raman Spectroscopy (SERS) to investigate polymer interdiffusion. Ultra-thin bilayer films of deuterated polystyrene (dPS) and polystyrene (PS) are placed in contact onto SERS-active gold substrates with inverted square-base pyramidal geometry and subsequently annealed. Initially, the Raman spectrum shows only spectral features of the polymer adjacent to the substrate. Upon annealing, Raman bands of the polymer located far from the substrate start to emerge, an indication of chain diffusion into the substrate hotspot and mixing between polymer layers. The kinetics of the process is consistent with transport of polymer chains in nanometer scale, with diffusion coefficients in the range 10-13 - 10-15cm2/s. The temperature response of the process is characterized by an activation energy of 48.93±1.5 kcal/mol, in excellent agreement with earlier experiments. SERS experiments provide a powerful and reliable experimental platform to characterize polymer interdiffusion without the need of chemical labeling, with several prospective applications to the study of chain dynamics in advanced polymer-based nanocomposite materials. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

FeO(1 1 1) films grown on a Au(1 1 1) substrate were studied in the low temperature CO oxidation reaction at near-atmospheric pressure. Enhanced reactivity over the otherwise inert Au(1 1 1) surface was only observed if the iron oxide films possessed so-called 'weakly bound oxygen' (WBO) species upon oxidation at elevated pressures. The reaction rate measured under O-rich conditions (CO/O2=1/5, totally 60 mbar, He balance to 1 bar) was found to correlate with the total amount of WBO measured in the 'oxidized' films by temperature programmed desorption. The initial reaction rate measured as a function of the film coverage showed a maximum at about one monolayer (ML), in contrast to ≈0.4 ML obtained for the Pt(1 1 1)-supported FeO(1 1 1) films measured with the same setup. When compared to FeO(1 1 1)/Pt(1 1 1), WBO species on FeO(1 1 1)/Au(1 1 1) desorb at a much lower (i.e., by ≈200 K) temperature, but also in much smaller amounts. Scanning tunneling microscopy studies showed that the FeO(1 1 1) layer on Au(1 1 1) is fairly stable towards high pressure oxidation in the low coverage regime, but undergoes substantial reconstruction at near-monolayer coverages, thus resulting in poorly-defined structures. Comparison of structure-reactivity relationships observed for Au(1 1 1) and Pt(1 1 1) supported FeO(1 1 1) films revealed the complex role of a metal support on reactivity. Although a strong interaction with the Pt(1 1 1) surface stabilizes a planar FeO(1 1 1)-derived structure for the active oxide phase, in the case of a more weakly interacting Au(1 1 1) surface, the reaction atmosphere induces structural transformations governed by the thermodynamic phase diagram of the iron oxide, albeit it seems crucial to have a dense FeO(1 1 1) film as the precursor. [ABSTRACT FROM AUTHOR]

Recent development in epidermal and bionic electronics systems has promoted the increasing demand for supercapcacitors with micrometer-thickness and good compatibility. Here, a highly flexible free-standing epidermal supercapacitor (SC-E) with merely 1 μm thickness and high performance is developed. Single-walled carbon nanotube/poly(3,4-ethylenedioxythiophene) hybrid films with unique inner-connected reticulation are adopted as electrodes for ultrathin structure and high electric conductivity. Then, based on two substrates with different surface energies, a stepwise lift-off method is presented to peel off the ultrathin integrated supercapacitor from the substrates nondestructively. As a result of the high conductive hybrid electrodes and the thin electrolyte layer, the as-designed supercapacitors (based on the total mass of two electrodes) achieve a good capacitance of 56 F g−1 and a superhigh power density of 332 kW kg−1, which manifest superior performance in contrast to the other devices fabricated by traditional electrodes. Meanwhile, the ultrashort response time of 11.5 ms enables the epidermal supercapacitor (SC-E) work for high-power units. More importantly, the free-standing structure and outstanding flexibility (105 times bending) endow the SC-E with excellent compatibility to be integrated and work in the next generation of smart and epidermal systems. [ABSTRACT FROM AUTHOR]

ABSTRACT Manipulation of optical transmission using plasmonic nanostructures is a significant issue in applications related to ultra-compact optoelectronic devices. In this paper, we present a type of plasmonic frequency selective surface constructed with an ultrathin gold film (∼20 nm) with arrays of subwavelength holes. By means of modified nanosphere lithography, we fabricate the nanostructured gold films with scalable sizes and tunable transmission in the visible and near-infrared range. Moreover, electromagnetic simulations are performed and demonstrate good agreement with experimental results and further reveal the evolution of optical properties from the optically thick film to the ultrathin film. The research achievements will provide significant design guidance of ultrathin plasmonic frequency selective surface for future nanophotonic devices. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2171-2176, 2016 [ABSTRACT FROM AUTHOR]

Abstract: Healable films with structural color are highly desirable and have a variety of potential applications. However, combining structural color with self‐healing properties to obtain new functional materials is a big challenge in current research. Herein, we present the first example of a color tunable, ultrathin film that can self‐heal in response to external mechanical abrasion. It is designed based on intermolecular hydrogen bonding interaction; the synthetic strategy involves spin‐coating of poly(acrylic acid) (PAA) and chitosan (CS). The successful preparation of ultrathin, healable, structural color films provides a new type of biomimetic material. [ABSTRACT FROM AUTHOR]

Surface-active polymers that display nonfouling properties and carry binding groups that can adsorb onto different substrates are highly desirable. We present a postmodification protocol of an active-ester-containing polymer that allows the creation of such a versatile platform. Poly(pentafluorophenyl acrylate) has been postmodified with a fixed grafting ratio of a nonfouling function (mPEG) and various combinations of functional groups, such as amine, silane and catechol, which can provide strong affinity to two model substrates: SiO2 and TiO2. Adsorption, stability and resistance to nonspecific protein adsorption of the polymer films were studied. A polymer was obtained that maintained its surface functionality under a variety of harsh conditions. EG surface-density calculations show that this strategy generates a denser packing when both negatively and positively charged groups are present within the backbone, and readily allows the fabrication of a broad combinatorial matrix. [ABSTRACT FROM AUTHOR]

There are increasing requirements for highly efficient and solvent-resistant nanoporous membranes in various separation processes. Traditional membranes usually have a poor solvent resistance and a thick skin layer leading to a low permeation flux. Currently, the major challenge lies in fabrication of ultrathin few-nanometers-pore membranes for fast organic filtration. Herein, a facile approach is presented to prepare ultrafine cellulose nanofibers for fabrication of ultrathin nanoporous membranes. The obtained nanofibers have a uniform diameter of 7.5 ± 2.5 nm and are homogeneously dispersed in aqueous solutions that are favorable to the fabrication of ultrathin nanoporous membranes. The resulting cellulose nanoporous membranes have an adjustable thickness down to 23 nm and pore sizes ranging from 2.5 to 12 nm. They allow fast permeation of water and organics during pressure-driven filtration. Typically, the 30 nm thick membrane has high fluxes of 1.14 and 3.96 × 104 L h−1 m−2 bar−1 for pure water and acetone respectively. Furthermore, the as-prepared cellulose nanofibers are easily employed to produce a novel syringe filter with sub-10 nm pores that have a wide application in fast separation and purification of nanoparticles on few-nanometers scale. [ABSTRACT FROM AUTHOR]

Simultaneously synthesizing and structuring atomically thick or ultrathin 2D non-precious metal nanocrystal may offer a new class of materials to replace the state-of-art noblemetal electrocatalysts; however, the synthetic strategy is the bottleneck which should be urgently solved. Here we report the synthesis of an ultrathin nickel nanosheet array (Ni-NSA) through in situ topotactic reduction from Ni(OH)2 array precursors. The Ni nanosheets showed a single-crystalline lamellar structure with only ten atomic layers in thickness and an exposed (111) facet. Combined with a superaerophobic (low bubble adhesive) arrayed structure the Ni-NSAs exhibited a dramatic enhancement on both activity and stability towards the hydrazine-oxidation reaction (HzOR) relative to platinum. Furthermore, the partial oxidization of Ni-NSAs in ambient atmosphere resulted in effective water-splitting electrocatalysts for the hydrogen-evolution reaction (HER). [ABSTRACT FROM AUTHOR]

In this paper we present the results of an XPS study of the surface chemistry of In2O3 (IO) ultrathin deposited by rheotaxial growth and vacuum oxidation after their air exposure and subsequent UHV annealing. For the freshly deposited RGVO IO ultrathin films the relative [O]/[In] concentration is equal to 1.17 ±0.05. After exposure to air it increases to 1.25 ±0.05. However, a strong C contamination appears, confirmed by the relative [C]/[In] concentration that is equal to 1.07 ±0.05. After subsequent UHV annealing at 200 °C the relative [O]/[In] concentration remains and only slightly increases to 1.30 ±0.05 after subsequent UHV annealing at 350 °C. After this process the relative [C]/[In] concentration decreases to 0.43 ±0.05. The additional AFM experiments showed that the RGVO IO ultrathin films exhibit the granular-type surface morphology, with an average grain height and width in the range of 2-5 nm, and 10-50 nm, respectively, and an average roughness of 1.1 nm. [ABSTRACT FROM AUTHOR]

The article discusses a study describing a novel humidity sensor consisting of dopamine-melanin thin films that form and self-assemble at air/solution interface. Topics include role of humidity in technology and human activities, development of moisture-responsive nanomaterials led by modern technological advances, and characteristics of biomaterial exhibited including ultrasensitivity, fast response and recovery behavior, and good reproducibility.

Stimuli-responsive nanoporous membranes have attracted increasing interest in various fields due to their abrupt changes of permeation/separation in response to the external environment. Here we report ultrathin pH-sensitive nanoporous membranes that are easily fabricated by the self-assembly of poly(acrylic acid) (PAA) in a metal hydroxide nanostrand solution. PAA-adsorbed nanostrands (2.5-5.0 nm) and PAA-CuII nanogels (2.0-2.5 nm) grow competitively during self-assembly. The PAA-adsorbed nanostrands are deposited on a porous support to fabricate ultrathin PAA membranes. The membranes display ultrafast water permeation and good rejection as well as significant pH-sensitivity. The 28 nm-thick membrane has a water flux decrease from 3740 to 1350 L m−1 h−1 bar−1 (pH 2.0 to 7.0) with a sharp decrease at pH 5.0. This newly developed pH-sensitive nanoporous membranes may find a wide range of applications such as controlled release and size- and charge-selective separation. [ABSTRACT FROM AUTHOR]

Nanoscale morphology of vanadium dioxide (VO2) films can be controlled to realize smooth ultrathin (<10 nm) crystalline films or nanoparticles with atomic layer deposition, opening doors to practical VO2 metal-insulator transition (MIT) nanoelectronics. The precursor combination, the valence of V, and the density for as-deposited VO2 films, as well as the postdeposition crystallization annealing conditions determine whether a continuous thin film or nanoparticle morphology is obtained. It is demonstrated that the films and particles possess both a structural and an electronic transition. The resistivity of ultrathin films changes by more than two orders of magnitude across the MIT, demonstrating their high quality. [ABSTRACT FROM AUTHOR]

We report the effects of varying specimen thickness on the generation of transmission Kikuchi patterns in the scanning electron microscope. Diffraction patterns sufficient for automated indexing were observed from films spanning nearly three orders of magnitude in thickness in several materials, from 5 nm of hafnium dioxide to 3 μm of aluminum, corresponding to a mass‐thickness range of ∼5 to 810 μg cm–2. The scattering events that are most likely to be detected in transmission are shown to be very near the exit surface of the films. The energies, spatial distribution and trajectories of the electrons that are transmitted through the film and are collected by the detector are predicted using Monte Carlo simulations. [ABSTRACT FROM AUTHOR]

A novel strategy to prepare a surface confined molecularly imprinted polymer (MIP) film directly on a transducer surface for protein sensing is achieved by combining interaction with a natural binding receptor and binding to a fully synthetic MIP. A thiolated oligoethyleneglycol (OEG)/mannose conjugate is first self-assembled on the transducer surface. Then the carbohydrate binding protein, concanavalin A (ConA), is 'vectorially' immobilized as a submonolayer on the underlying mannose modified surface. Afterwards, an ultrathin polyscopoletin film with the thickness comparable to that of the protein is electrodeposited on the top. This architecture ensures that the target is confined to the film surface. The resulting functional material shows an approximately 20-fold higher affinity than that obtained from the mannose self-assembled monolayer. This result shows a synergism between multivalent binding of the natural sugar ligand and the non-covalent interactions of the target within the MIP cavities. Recognition capability of the film is characterized by a real-time measurement using quartz crystal microbalance. In comparison to the non-imprinted film, the imprinted film reveals 8.6 times higher binding capacity towards ConA. High discrimination towards the target protein's homologues shows size and shape specificity of the imprint. [ABSTRACT FROM AUTHOR]

X-ray magnetic circular dichroism (XMCD) is one of the most powerful tools for investigating the magnetic properties of different types of materials that display ferromagnetic behavior. Compared with other magnetic-sensitive techniques, XMCD has the advantage of being element specific and is capable of separating the spin and magnetic moment contributions associated with each element in the sample. In samples involving, for example, buried atoms, clusters on surfaces or at interfaces, ultrathin films, nanoparticles and nanostructures, three experimental conditions must be present to perform state-of-the-art XMCD measurements: high magnetic fields, low temperatures and an ultra-highvacuum environment. This paper describes a new apparatus that can be easily installed at different X-ray and UV beamlines at the Brazilian Synchrotron Light Laboratory (LNLS). The apparatus combines the three characteristics described above and different methods to measure the absorption signal. It also permits in situ sample preparation and transfer to another chamber for measurement by conventional surface science techniques such as low-energy electron diffraction (LEED), reflection high-energy electron diffraction (RHEED), X-ray photoelectron spectroscopy (XPS) and X-ray photoelectron diffraction (XPD). Examples are given of XMCD measurements performed with this set-up on different materials. [ABSTRACT FROM AUTHOR]

Highlights from the article: Keywords: flexible and transparent electronics; gold films; optical constants; 2D materials; ultrathin films Ultrathin and ultrasmooth Au films are realized on 2D MoS SB 2 sb adhesion layers. Flexible and transparent electronics, gold films, optical constants, 2D materials, ultrathin films.

Sub‐10 nm continuous metal films are promising candidates for flexible and transparent nanophotonics and optoelectronic applications. In this article, it is demonstrated that monolayer MoS2 is a perspective adhesion layer for the deposition of continuous conductive gold films with a thickness of only 3–4 nm. Optical properties of continuous ultrathin gold films deposited on 2D MoS2 grown by chemical vapor deposition are investigated by spectroscopic ellipsometry over a wide wavelength range (300–3300 nm). Results show that optical losses in ultrathin films increase with decreasing thickness due to the fine‐grained structure and the presence of a small number of voids, however, they exhibit metallic properties down to a thickness of 3–4 nm. The atomic‐scale MoS2 interfaces can be transferred to any substrate and thus open up new opportunities for the creation of metasurfaces and a new type of van der Waals heterostructures with atomically thin metal layers. [ABSTRACT FROM AUTHOR]

Conductive and transparent ultra‐thin Nickel films are grown by RF sputtering on fused silica substrates. The characteristics of Ni films (thickness, refractive index, and extinction coefficient) are obtained by fitting multi‐angle spectrophotometric and ellipsometric data. Films thickness inferred by X ray reflection (XRR) measurements is in good accordance with ellipsometric results. XPS analysis reveals that Ni metal phase is present in the film surface together with Ni mixed oxide phases, which explains the high electrical stability of such films. Ultra‐thin films play a key‐role in several technological applications. The authors report on the accurate characterization of ultrathin (5–8 nm) Ni films grown by RF sputtering. Thickness and optical constants are inferred by fitting multi‐angle spectrophotometric and ellipsometric data. Thickness values are in very good agreement with XRR results, and higher than the ones estimated by the sputtering rate obtained by profilometry measurements. [ABSTRACT FROM AUTHOR]

Thin and ultrathin polymer films play an important role in a variety of applications, such as electronics, liquid crystal alignment, adhesion, and so on. It is well established that the properties of semicrystalline polymeric materials depend remarkably on their multiscale structures; for example, an increase of more than a factor of 100 has been reported for the electrical conductivity of doped and aligned conjugated macromolecules compared with their nonoriented counterparts. Consequently, sophisticated methods have been developed for preparing highly oriented polymer ultrathin films. It should be pointed out that the highly oriented crystalline structure of polymers can be maintained only at temperatures below their melting points. Otherwise, structure rearrangement will result in the loss of orientation and therefore the properties. Therefore, self‐repairing of highly oriented polymer structures is of great significance for the long‐term application of polymer thin films in some specific fields. In this review paper, the preparation and self‐repair of the highly oriented structure of polymer thin films is described in the hopes that this will afford useful information for further development of polymeric materials for advanced applications. Self‐repairing materials have the potential for long‐term applications and are realized through dynamic chemical bonds or weak interactions. Here, a new way for self‐repairing the highly oriented structure of ultrathin polymer films through surface carbon coating during melt recrystallization is introduced. [ABSTRACT FROM AUTHOR]

A high‐performing epidermal supercapacitor is presented W. Y. Zhou, Z. Q. Niu, S. S. Xie, and co‐workers on page 8178. The micrometer‐thin and extremely flexible supercapacitor can reveal the subtle skin texture and manifest a practical potential to power other devices, which is promising for future smart and epidermal systems. [ABSTRACT FROM AUTHOR]