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Transition metal dichalcogenides (TMDs) have received considerable attention as promising electrocatalysts for the hydrogen evolution reaction (HER), yet their potential is often constrained by the inertness of the basal planes arising from their poor hydrogen adsorption ability. Here, the relationship between the electronic structure of the WS 2 basal plane and HER activity is systemically analyzed to establish a clear insight. The valance state of the sulfur atoms on the basal plane has been tuned to enhance hydrogen adsorption through sequential engineering processes, including direct phase transition and heterostructure that induces work function-difference-induced unidirectional electron transfer. Additionally, an innovative synthetic approach, harnessing the built-in internal polarization field at the W-graphene heterointerface, triggers the in-situ formation of sulfur vacancies in the bottom WS x (x < 2) layers. The resultant modulation of the valance state of the sulfur atom stabilizes the W-S bond, while destabilizing the S-H bond. The electronic structural changes are further amplified by the release and transfer of surplus electrons via sulfur vacancies, filling the valance state of W and S atoms. Consequently, this work provides a comprehensive understanding of the interplay between the electronic structure of the WS 2 basal plane and the HER activity, focusing on optimizing S-H bonding state., (© 2024 Wiley‐VCH GmbH.)

The commercialization of 3D heterogeneous integration through hybrid bonding has accelerated, and accordingly, Cu-polymer bonding has gained significant attention as a means of overcoming the limitations of conventional Cu-SiO 2 hybrid bonding, offering high compatibility with other fabrication processes. Polymers offer robust bonding strength and a low dielectric constant, enabling high-speed signal transmission with high reliability, but suffer from low thermomechanical stability. Thermomechanical stability of polymers was not achieved previously because of thermal degradation and unstable anchoring. To overcome these limitations, wafer-scale Cu-polymer bonding via N-heterocyclic carbene (NHC) nanolayers was presented for 3D heterogeneous integration, affording ultrastable packing density, crystallinity, and thermal properties. NHC nanolayers were deposited on copper electrodes via electrochemical deposition, and wafer-scale 3D heterogeneous integration was achieved by adhesive bonding at 170 °C for 1 min. Ultrastable conductivity and thermomechanical properties were observed by the spatial mapping of conductivity, work function, and force-distance curves. With regard to the characterization of NHC nanolayers, low-temperature bonding, robust corrosion inhibition, enhanced electrical conductivity, back-end-of-line process compatibility, and fabrication process reduction, NHC Cu/polymer bonding provides versatile advances in 3D heterogeneous integration, indicating that NHC Cu/polymer bonding can be utilized as a platform for future 3D vertical chip architectures.

Two-dimensional (2D) ferroelectric materials have emerged as significant platforms for multi-functional three-dimensional (3D) integrated electronic devices. Among 2D ferroelectric materials, ferro-ionic CuInP 2 S 6 has the potential to achieve the versatile advances in neuromorphic computing systems due to its phase tunability and ferro-ionic characteristics. As CuInP 2 S 6 exhibits a ferroelectric phase with insulating properties at room temperature, the external temperature and electrical field should be required to activate the ferro-ionic conduction. Nevertheless, such external conditions inevitably facilitate stochastic ionic conduction, which completely limits the practical applications of 2D ferro-ionic materials. Herein, free-standing 2D ferroelectric heterostructure is mechanically manipulated for nano-confined conductive filaments growth in free-standing 2D ferro-ionic memristor. The ultra-high mechanical bending is selectively facilitated at the free-standing area to spatially activate the ferro-ionic conduction, which allows the deterministic local positioning of Cu + ion transport. According to the local flexoelectric engineering, 5.76×10 2 -fold increased maximum current is observed within vertical shear strain 720 nN, which is theoretically supported by the 3D flexoelectric simulation. In conclusion, we envision that our universal free-standing platform can provide the extendable geometric solution for ultra-efficient self-powered system and reliable neuromorphic device., (© 2024. The Author(s).)

Mesoporous metal oxides exhibit excellent physicochemical properties and are widely used in various fields, including energy storage/conversion, catalysis, and sensors. Although several soft-template approaches are reported, high-temperature calcination for both metal oxide formation and template removal is necessary, which limits direct synthesis on a plastic substrate for flexible devices. Here, a universal synthetic approach that combines thermal activation and oxygen plasma to synthesize diverse mesoporous metal oxides (V 2 O 5 , V 6 O 13 , TiO 2 , Nb 2 O 5 , WO 3, and MoO 3 ) at low temperatures (150-200 °C), which can be applicable to a flexible polymeric substrate is introduced. As a demonstration, a flexible micro-supercapacitor is fabricated by directly synthesizing mesoporous V 2 O 5 on an indium-tin oxide-coated colorless polyimide film. The energy storage performance is well maintained under severe bending conditions., (© 2024 Wiley‐VCH GmbH.)

Molecular electronics enables functional electronic behavior via single molecules or molecular self-assembled monolayers, providing versatile opportunities for hybrid molecular-scale electronic devices. Although various molecular junction structures are constructed to investigate charge transfer dynamics, significant challenges remain in terms of interfacial charging effects and far-field background signals, which dominantly block the optoelectrical observation of interfacial charge transfer dynamics. Here, tip-induced optoelectrical engineering is presented that synergistically correlates photo-induced force microscopy and Kelvin probe force microscopy to remotely control and probe the interfacial charge transfer dynamics with sub-10 nm spatial resolution. Based on this approach, the optoelectrical origin of metal-molecule interfaces is clearly revealed by the nanoscale heterogeneity of the tip-sample interaction and optoelectrical reactivity, which theoretically aligned with density functional theory calculations. For a practical device-scale demonstration of tip-induced optoelectrical engineering, interfacial tunneling is remotely controlled at a 4-inch wafer-scale metal-insulator-metal capacitor, facilitating a 5.211-fold current amplification with the tip-induced electrical field. In conclusion, tip-induced optoelectrical engineering provides a novel strategy to comprehensively understand interfacial charge transfer dynamics and a non-destructive tunneling control platform that enables real-time and real-space investigation of ultrathin hybrid molecular systems., (© 2023 The Authors. Advanced Science published by Wiley-VCH GmbH.)

Ordered mesoporous carbons (OMCs) are promising materials for cathode materials of a Zn ion hybrid capacitor (Zn HC) due to their high surface area and interconnected porous structure. Graphitization of the framework and nitrogen doping have been used to improve the energy storage performance of the OMCs by enhancing electrical conductivity, pseudocapacitive reaction sites, and surface affinity toward aqueous electrolytes. Thus, when both methods are simultaneously implemented to the OMCs, the Zn HC would have improved energy storage performance. Herein, we introduce a facile synthetic method for N-doped mesoporous graphitic carbon (N-mgc) by utilizing polystyrene- block -poly(2-vinlypyridine) copolymer (PS- b -P2VP) as both soft-template and carbon/nitrogen sources. Co-assembly of PS- b -P2VP with Ni precursors for graphitization formed a mesostructured composite, which was converted to N-doped graphitic carbon through catalytic pyrolysis. After selective removal of Ni, N-mgc was prepared. The obtained N-mgc exhibited interconnected mesoporous structure with high nitrogen content and high surface area. When N-mgc was employed as a cathode material in Zn ion HC, excellent energy storage performance was achieved: a high specific capacitance (43 F/g at 0.2 A/g), a high energy density of 19.4 Wh/kg at a power density of 180 W/kg, and reliable cycle stability (>3000 cycles).

Memristors mimic synaptic functions in advanced electronics and image sensors, thereby enabling brain-inspired neuromorphic computing to overcome the limitations of the von Neumann architecture. As computing operations based on von Neumann hardware rely on continuous memory transport between processing units and memory, fundamental limitations arise in terms of power consumption and integration density. In biological synapses, chemical stimulation induces information transfer from the pre- to the post-neuron. The memristor operates as resistive random-access memory (RRAM) and is incorporated into the hardware for neuromorphic computing. Hardware composed of synaptic memristor arrays is expected to lead to further breakthroughs owing to their biomimetic in-memory processing capabilities, low power consumption, and amenability to integration; these aspects satisfy the upcoming demands of artificial intelligence for higher computational loads. Among the tremendous efforts toward achieving human-brain-like electronics, layered 2D materials have demonstrated significant potential owing to their outstanding electronic and physical properties, facile integration with other materials, and low-power computing. This review discusses the memristive characteristics of various 2D materials (heterostructures, defect-engineered materials, and alloy materials) used in neuromorphic computing for image segregation or pattern recognition. Neuromorphic computing, the most powerful artificial networks for complicated image processing and recognition, represent a breakthrough in artificial intelligence owing to their enhanced performance and lower power consumption compared with von Neumann architectures. A hardware-implemented CNN with weight control based on synaptic memristor arrays is expected to be a promising candidate for future electronics in society, offering a solution based on non-von Neumann hardware. This emerging paradigm changes the computing algorithm using entirely hardware-connected edge computing and deep neural networks.

Graphene is a promising active material for electric double layer supercapacitors (EDLCs) due to its high electric conductivity and lightweight nature. However, for practical uses as a power source of electronic devices, a porous structure is advantageous to maximize specific energy density. Here, we propose a facile fabrication approach of mesoporous graphene ( m -G), in which self-assembled mesoporous structures of poly(styrene)- block -poly(2-vinylpyridine) copolymer (PS- b -P2VP) are exploited as both mesostructured catalytic template and a carbon source. Notably, the mesostructured catalytic template is sufficient to act as a rigid support without structural collapse, while PS- b -P2VP converts to graphene, generating m -G with a pore diameter of ca. 3.5 nm and high specific surface area of 186 m 2 /g. When the EDLCs were prepared using the obtained m -G and ionic liquids, excellent electrochemical behaviors were achieved even at high operation voltages (0 ∼ 3.5 V), including a large specific capacitance (130.2 F/g at 0.2 A/g), high-energy density of 55.4 W h/kg at power density of 350 W/kg, and excellent cycle stability (>10,000 cycles). This study demonstrates that m -G is a promising material for high-performance energy storage devices.

Among the transition metal dichalcogenides (TMD), tungsten disulfide (WS 2 ) and molybdenum disulfide (MoS 2 ) are promising sulfides for replacing noble metals in the hydrogen evolution reaction (HER) owing to their abundance and good catalytic activity. However, the catalytic activity is derived from the edge sites of WS 2 and MoS 2 , while their basal planes are inert. We propose a novel process for N-doped TMD synthesis for advanced HER using N 2  + Ar + H 2 S plasma. The high ionization energy of Ar gas enabled nitrogen species activation results in efficient N-doping of TMD (named In situ-MoS 2 and In situ-WS 2 ). In situ-MoS 2 and WS 2 were characterized by various techniques (Raman spectroscopy, XPS, HR-TEM, TOF-SIMS, and OES), confirming nanocrystalline and N-doping. The N-doped TMD were used as electrocatalysts for the HER, with overpotentials of 294 mV (In situ-MoS 2 ) and 298 mV (In situ-WS 2 ) at a current density of 10 mA cm -2 , which are lower than those of pristine MoS 2 and WS 2 , respectively. Density functional theory (DFT) calculations were conducted for the hydrogen Gibbs energy (∆G H ) to investigate the effect of N doping on the HER activity. Mixed gas plasma proposes a facile and novel fabrication process for direct N doping on TMD as a suitable HER electrocatalyst., (© 2022. The Author(s).)

The bifunctionality of chromism-integrated sensors and devices has been highlighted because of their reversibility, fast response, and visual indication. For example, one of the representative chromism electrochromic materials exhibits optical modulation under ion insertion/extraction by applying a potential. This operation mechanism can be integrated with various sensors (pressure, strain, biomolecules, gas, etc.) and devices (energy conversion/storage systems) as visual indicators for user-friendly operation. In this review, recent advances in the field of chromism-integrated systems for visual indicators are categorized for various chromism-integrated sensors and devices. This review can provide insights for researchers working on chromism, sensors, or devices. The integrated chromic devices are evaluated in terms of coloration-bleach operation, cycling stability, and coloration efficiency. In addition, the existing challenges and prospects for chromism-integrated sensors and devices are summarized for further research.

Using tungsten disulfide (WS 2 ) as a hydrogen evolution reaction (HER) electrocatalyst brought on several ways to surpass its intrinsic catalytic activity. This study introduces a nanodomain tungsten oxide (WO 3 ) interface to 1T-WS 2 , opening a new route for facilitating the transfer of a proton to active sites, thereby enhancing the HER performance. After H 2 S plasma sulfurization on the W layer to realize nanocrystalline 1T-WS 2 , subsequent O 2 plasma treatment led to the formation of amorphous WO 3 (a-WO 3 ), resulting in a patchwork-structured heterointerface of 1T-WS 2 /a-WO 3 (WSO). Addition of a hydrophilic interface (WO 3 ) facilitates the hydrogen spillover effect, which represents the transfer of absorbed protons from a-WO 3 to 1T-WS 2 . Moreover, the faster response of the cathodic current peak (proton insertion) in cyclic voltammetry is confirmed by the higher degree of oxidation. The rationale behind the faster proton insertion is that the introduced a-WO 3 works as a proton channel. As a result, WSO-1.2 (the ratio of 1T-WS 2 to a-WO 3 ) exhibits a remarkable HER activity in that 1T-WS 2 consumes more protons provided by the channel, showing an overpotential of 212 mV at 10 mA/cm 2 . Density functional theory calculations also show that the WO 3 phase gives higher binding energies for initial proton adsorption, while the 1T-WS 2 phase shows reduced HER overpotential. This improved catalytic performance demonstrates a novel strategy for water splitting to actively elicit the related reaction via efficient proton transport.

Two-dimensional (2D) transition metal dichalcogenides (TMDs) have attracted attention as polymorphs depending on their phases (1T and 2H) when applying typical synthesis methods. The 2H phase is generally synthesised through chemical vapour deposition (CVD) on a wafer-scale at high temperatures, and many synthesis methods have been reported owing to their thermodynamic stability and semiconductor properties. By contrast, although the 1T phase is meta-stable with an octahedral coordination, thereby limiting the use of synthesis methods, the recent structural advantage in terms of the hydrogen evolution reaction (HER) has been emphasised. Despite this demand, no large-area thin-film synthesis method for 1T-TMDs has been developed. Among several strategies of synthesizing metallic-phase (1T) TMDs, chemical exfoliation (alkali metal intercalation) is a major strategy and others have been used for electron-beam irradiation, laser irradiation, defects, plasma hot electron transfer, and mechanical strain. Therefore, we suggest an innovative synthesis method using plasma-enhanced CVD (PECVD) for both the 1T and 2H phases of TMDs (MoS 2 and WS 2 ). Because ions and radicals are accelerated to the substrate within the sheath region, a high-temperature source is not needed for vapour ionisation, and thus the process temperature can be significantly lowered (150 °C). Moreover, a 4-inch wafer-scale of a thin film is an advantage and can be synthesised on arbitrary substrates (SiO 2 /Si wafer, glassy carbon electrode, Teflon, and polyimide). Furthermore, the PECVD method was applied to TMD-graphene heterostructure films with a graphene-transferred substrate, and for the first time, sequential metal seed layer depositions of W (1 nm) and Mo (1 nm) were sulfurized to MoS 2 -WS 2 vertical heterostructures with Ar + H 2 S plasma. We considered the prospects and challenges of the new PECVD method in the development of practical applications in next-generation integrated electronics, HER catalysts, and flexible biosensors., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The effects of photo-oxidative degradation of polyacids at various concentrations and with different durations of ultraviolet (UV) irradiation on the photo-reduction of ceria nanoparticles were investigated. The effect of UV-treated ceria on the performance of chemical mechanical polishing (CMP) for the dielectric layer was also evaluated. When the polyacids were exposed to UV light, they underwent photo-oxidation with consumption of the dissolved oxygen in slurry. UV-treated ceria particles formed oxygen vacancies by absorbing photon energy, resulting in increased Ce 3+ ions concentration on the surface, and when the oxygen level of the solution was lowered by the photo-oxidation of polymers, the formation of Ce 3+ ions was promoted from 14.2 to 36.5%. Furthermore, chain scissions of polymers occurred during the oxidation process, and polyacids with lower molecular weights were found to be effective in ceria particle dispersion in terms of the decrease in the mean diameter and size distribution maintaining under 0.1 of polydispersity index. With increasing polyacid concentration and UV irradiation time, the Ce 3+ concentration and the dispersity of ceria both increased due to the photo-oxidative degradation of the polymer; this enhanced the CMP performance in terms of 87% improved material removal rate and 48% lowered wafer surface roughness., (© 2022. The Author(s).)

The recent outbreak of COVID-19 has highlighted the seriousness of airborne diseases and the need for a proper pathogen detection system. Compared to the ample amount of research on biological detection, work on integrated devices for air monitoring is rare. In this work, we integrated a wet-cyclone air sampler and a DC impedance microfluidic cytometer to build a cyclone-cytometer integrated air monitor (CCAM). The wet-cyclone air sampler sucks the air and concentrates the bioaerosols into 10 mL of aqueous solvent. After 5 min of air sampling, the bioaerosol-containing solution was conveyed to the microfluidic cytometer for detection. The device was tested with aerosolized microbeads, dust, and Escherichia coli (E. coli). CCAM is shown to differentiate particles from 0.96 to 2.95 μm with high accuracy. The wet cyclone air-sampler showed a 28.04% sampling efficiency, and the DC impedance cytometer showed 87.68% detection efficiency, giving a total of 24.59% overall CCAM efficiency. After validation of the device performance, CCAM was used to detect bacterial aerosols and their viability without any separate pretreatment step. Differentiation of dust, live E. coli, and dead E. coli was successfully performed by the addition of BacLight bacterial viability reagent in the sampling solvent. The usage could be further extended to detection of specific species with proper antibody fluorescent label. A promising strategy for aerosol detection is proposed through the constructive integration of a DC impedance microfluidic cytometer and a wet-cyclone air sampler., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Makers of point-of-care devices and wearable diagnostics prefer flexible electrodes over conventional electrodes. In this study, a flexible electrode platform is introduced with a WS 2 /graphene heterostructure on polyimide (WGP) for the concurrent and selective determination of dopamine and serotonin. The WGP is fabricated directly via plasma-enhanced chemical vapor deposition (PECVD) at 150 °C on a flexible polyimide substrate. Owing to the limitations of existing fabrication methods from physical transfer or hydrothermal methods, many studies are not conducted despite excellent graphene-based heterostructures. The PECVD synthesis method can provide an innovative WS 2 /graphene heterostructure of uniform quality and sufficient size (4 in.). This unique heterostructure affords excellent electrical conductivity in graphene and numerous electrochemically active sites in WS 2 . A large number of uniform qualities of WGP electrodes show reproducible and highly sensitive electrochemical results. The synergistic effect enabled well-separated voltammetric signals for dopamine and serotonin with a potential gap of 188 mV. Moreover, the practical application of the flexible sensor is successfully evaluated by using artificial cerebrospinal fluid., (© 2021 Wiley-VCH GmbH.)

Nanostructural modification of two-dimensional (2D) materials has attracted significant attention for enhancing hydrogen evolution reaction (HER) activity. In this study, the nanostructure of TaS 2 films was controlled by controlling the Ar/H 2 S gas ratio used in plasma-enhanced chemical vapor deposition (PECVD). At a high Ar/H 2 S gas ratio, vertically aligned TaS 2 (V-TaS 2 ) films were formed over a large-area (4 in) at a temperature of 250 °C, which, to the best of our knowledge, is the lowest temperature reported for PECVD. Furthermore, the plasma species formed in the injected gas at various Ar/H 2 S gas ratios were analyzed using optical emission spectroscopy to determine the synthesis mechanism. In addition, the 4 in wafer-scale V-TaS 2 was analyzed by x-ray photoelectron spectroscopy, transmission electron microscopy, and atomic force microscopy, and the HER performance of the as-synthesized TaS 2 fabricated with various Ar/H 2 S ratios was measured. The results revealed that, depending on the film structure of TaS 2 , the HER performance can be enhanced owing to its structural advantage. Furthermore, the excellent stability and robustness of V-TaS 2 was confirmed by conducting 1000 HER cycles and post-HER material characterization. This study provides important insights into the plasma-assisted nanostructural modification of 2D materials for application as enhanced electrocatalysts., (© 2021 IOP Publishing Ltd.)

The octahedral structure of 2D molybdenum disulfide (1T-MoS 2 ) has attracted attention as a high-efficiency and low-cost electrocatalyst for hydrogen production. However, the large-scale synthesis of 1T-MoS 2 films has not been realized because of higher formation energy compared to that of the trigonal prismatic phase (2H)-MoS 2 . In this study, a uniform wafer-scale synthesis of the metastable 1T-MoS 2 film is performed by sulfidation of the Mo metal layer using a plasma-enhanced chemical vapor deposition (PE-CVD) system. Thus, plasma-containing highly reactive ions and radicals of the sulfurization precursor enable the synthesis of 1T-MoS 2 at 150 °C. Electrochemical analysis of 1T-MoS 2 shows enhanced catalytic activity for the hydrogen evolution reaction (HER) compared to that of previously reported MoS 2 electrocatalysts 1T-MoS 2 does not transform into stable 2H-MoS 2 even after 1000 cycles of HER. The proposed low-temperature synthesis approach may offer a promising solution for the facile production of various metastable-phase 2D materials., (© 2021 Wiley-VCH GmbH.)

The conventional synthesis of two-dimensional (2D) transition metal dichalcogenide (TMDC) heterostructures is low yielding and lack the heterojunction interface quality. The chemical vapor deposition (CVD) techniques have achieved high-quality heterostructure interfaces but require a high synthesis temperature (>600 °C) and have a low yield of heterostructures. Therefore, the large scale and high interface quality of TMDC heterojunctions using low-temperature synthesis methods are in demand. Here, high-quality, wafer-scale MoS 2 and WS 2 heterostructures with 2D interfaces were prepared by a one-step sulfurization of the molybdenum (Mo) and tungsten (W) precursors via plasma-enhanced CVD at a relatively low temperature (150 °C). The 4 inch wafer-scale synthesis of the MoS 2 -WS 2 heterostructures was validated using various spectroscopic and microscopic techniques. Further, the photocurrent generation and photoswitching phenomenon of the so-obtained MoS 2 -WS 2 heterostructures were studied. The photodevice prepared by the MoS 2 -WS 2 heterostructures at 150 °C showed a photoresponsivity of 83.75 mA/W. The excellent photoresponse and faster photoswitching highlight the advantage of MoS 2 -WS 2 heterostructures toward advanced photodetectors.

Two-dimensional (2D) transition metal dichalcogenides (TMDs) have attracted considerable attention owing to their synergetic effects with other 2D materials, such as graphene and hexagonal boron nitride, in TMD-based heterostructures. Therefore, it is important to understand the physical properties of TMD-TMD vertical heterostructures for their applications in next-generation electronic devices. However, the conventional synthesis process of TMD-TMD heterostructures has some critical limitations, such as nonreproducibility and low yield. In this paper, we synthesize wafer-scale MoS 2 -WS 2 vertical heterostructures (MWVHs) using plasma-enhanced chemical vapor deposition (PE-CVD) via penetrative single-step sulfurization discovered by time-dependent analysis. This method is available for fabricating uniform large-area vertical heterostructures (4 in.) at a low temperature (300 °C). MWVHs were characterized using various spectroscopic and microscopic techniques, which revealed their uniform nanoscale polycrystallinity and the presence of vertical layers of MoS 2 and WS 2 . In addition, wafer-scale MWVHs diodes were fabricated and demonstrated uniform performance by current mapping. Furthermore, mode I fracture tests were performed using large double cantilever beam specimens to confirm the separation of the MWVHs from the SiO 2 /Si substrate. Therefore, this study proposes a synthesis mechanism for TMD-TMD heterostructures and provides a fundamental understanding of the interfacial properties of TMD-TMD vertical heterostructures.

Flexibile biosensors have a lot of applications in measuring the concentration of target bioanalytes. In combination with its flexibility, electrochemical sensors containing 2D materials have particular advantages such as enlarged area compatibility, transparency, and high scalability. A flexible biosensor was fabricated by direct synthesis of molybdenum disulfide (MoS 2 ) on a polyimide (PI) substrate, which can be used as the working electrode in electrochemistry platforms. The direct formation of 2D-MoS 2 on the PI was achieved using plasma-enhanced chemical vapor deposition (PE-CVD). Since the MoS 2 provides higher electrical conductivity, the MoS 2 -Au-PI flexible sensor is able to provide highly sensitive detection of target proteins with a relatively fast response via cyclic voltammetry. To evaluate the high performance of the fabricated sensor, we selected the endocrine-related hormones parathyroid hormone (PTH), triiodothyronine (T3), and thyroxine (T4) as analytes because they are one of the most important markers for the determination of endocrinopathy, however, they are very difficult to quantify. The newly developed biosensor achieved highly sensitive detection of the hormones and could determine their location with high accuracy. In addition, we performed electrochemical measurements of hormones obtained from 30 clinical patients' sera with confirmed agreement and compared with the measurements performed with standard immunoassay equipment (E 170, Roche Diagnostics, Germany).

The metallic 1T phase of WS 2 (1T-WS 2 ), which boosts the charge transfer between the electron source and active edge sites, can be used as an efficient electrocatalyst for the hydrogen evolution reaction (HER). As the semiconductor 2H phase of WS 2 (2H-WS 2 ) is inherently stable, methods for synthesizing 1T-WS 2 are limited and complicated. Herein, a uniform wafer-scale 1T-WS 2 film is prepared using a plasma-enhanced chemical vapor deposition (PE-CVD) system. The growth temperature is maintained at 150 °C enabling the direct synthesis of 1T-WS 2 films on both rigid dielectric and flexible polymer substrates. Both the crystallinity and number of layers of the as-grown 1T-WS 2 are verified by various spectroscopic and microscopic analyses. A distorted 1T structure with a 2a 0 × a 0 superlattice is observed using scanning transmission electron microscopy. An electrochemical analysis of the 1T-WS 2 film demonstrates its similar catalytic activity and high durability as compared to those of previously reported untreated and planar 1T-WS 2 films synthesized with CVD and hydrothermal methods. The 1T-WS 2 does not transform to stable 2H-WS 2 , even after a 700 h exposure to harsh catalytic conditions and 1000 cycles of HERs. This synthetic strategy can provide a facile method to synthesize uniform 1T-phase 2D materials for electrocatalysis applications., (© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)