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Abstract Solution-processable 2D semiconductor inks based on electrochemical molecular intercalation and exfoliation of bulk layered crystals using organic cations has offered an alternative pathway to low-cost fabrication of large-area flexible and wearable electronic devices. However, the growth of large-piece bulk crystals as starting material relies on costly and prolonged high-temperature process, representing a critical roadblock towards practical and large-scale applications. Here we report a general liquid-metal-assisted approach that enables the electrochemical molecular intercalation of low-cost and readily available crystal powders. The resulted solution-processable MoS2 nanosheets are of comparable quality to those exfoliated from bulk crystals. Furthermore, this method can create a rich library of functional 2D electronic inks ( >50 types), including 2D wide-bandgap semiconductors of low electrical conductivity. Lastly, we demonstrated the all-solution-processable integration of 2D semiconductors with 2D conductors and 2D dielectrics for the fabrication of large-area thin-film transistors and memristors at a greatly reduced cost.

Abstract Networks of nanowires, nanotubes, and nanosheets are important for many applications in printed electronics. However, the network conductivity and mobility are usually limited by the resistance between the particles, often referred to as the junction resistance. Minimising the junction resistance has proven to be challenging, partly because it is difficult to measure. Here, we develop a simple model for electrical conduction in networks of 1D or 2D nanomaterials that allows us to extract junction and nanoparticle resistances from particle-size-dependent DC network resistivity data. We find junction resistances in porous networks to scale with nanoparticle resistivity and vary from 5 Ω for silver nanosheets to 24 GΩ for WS2 nanosheets. Moreover, our model allows junction and nanoparticle resistances to be obtained simultaneously from AC impedance spectra of semiconducting nanosheet networks. Through our model, we use the impedance data to directly link the high mobility of aligned networks of electrochemically exfoliated MoS2 nanosheets (≈ 7 cm2 V−1 s−1) to low junction resistances of ∼2.3 MΩ. Temperature-dependent impedance measurements also allow us to comprehensively investigate transport mechanisms within the network and quantitatively differentiate intra-nanosheet phonon-limited bandlike transport from inter-nanosheet hopping.

Abstract The adjustable structures and remarkable physicochemical properties of 2D monoelemental materials, such as silicene and germanene, have attracted significant attention in recent years. They can be transformed into silicane (SiH) and germanane (GeH) through covalent functionalization via hydrogen atom termination. However, synthesizing these materials with a scalable and low‐cost fabrication process to achieve high‐quality 2D SiH and GeH poses challenges. Herein, groundbreaking 2D SiH and GeH materials with varying compositions, specifically Si0.25Ge0.75H, Si0.50Ge0.50H, and Si0.75Ge0.25H, are prepared through a simple and efficient chemical exfoliation of their Zintl phases. These 2D materials offer significant advantages, including their large surface area, high mechanical flexibility, rapid electron mobility, and defect‐rich loose‐layered structures. Among these compositions, the Si0.50Ge0.50H electrode demonstrates the highest discharge capacity, reaching up to 1059 mAh g−1 after 60 cycles at a current density of 75 mA g−1. A comprehensive ex‐situ electrochemical analysis is conducted to investigate the reaction mechanisms of lithiation/delithiation in Si0.50Ge0.50H. Subsequently, an initial assessment of the c‐Li15(SixGe1‐x)4 phase after lithiation and the a‐Si0.50Ge0.50 phase after delithiation is presented. Hence, this study contributes crucial insights into the (de)lithiation reaction mechanisms within germanane‐silicane alloys. Such understanding is pivotal for mastering promising materials that amalgamate the finest properties of silicon and germanium.

Abstract Platinum diselenide (PtSe2) has shown great potential as a candidate two‐dimensional (2D) material for broadband photodetectors and electrocatalysts because of its unique properties compared to conventional 2D transition metal dichalcogenides. Synthesis of 2D PtSe2 with controlled layer number is critical for engineering the electronic behavior to be semiconducting or semimetallic for targeted applications. Electrochemical exfoliation has been investigated as a promising approach for mass‐producing in a cost‐effective manner, but obtaining high‐quality films with control over electronic properties remains difficult. Here, we demonstrate wafer‐scale 2D PtSe2 films with pre‐determined electronic types based on a facile solution‐based strategy. Semiconducting or semimetallic PtSe2 nanosheets with large lateral sizes are produced via electrochemically driven molecular intercalation, followed by centrifugation‐based thickness sorting. Finally, gate‐tunable broadband visible and near‐infrared photodetector arrays are realized based on semiconducting PtSe2 nanosheet films, while semimetallic films are used to create catalytic electrodes for overall water splitting with long‐term stability.

Abstract Two-dimensional (2D) black phosphorus (BP), or phosphorene, has recently emerged as a promising 2D semiconductor because of its p-type charge transport behavior and near-infrared photoresponsivity. However, the application of BP in practical electronic and optoelectronic devices is hindered by challenges in producing high-quality BP films over large areas. In this manuscript, we present a facile solution-based process to create wafer-scale BP films for fabrication of p-channel field-effect transistors that are responsive to near infrared light. Few-layer BP nanosheets are first exfoliated from the bulk crystal via electrochemical intercalation of cationic molecules and then vacuum-filtered through an anodic aluminum oxide membrane. The resulting BP film can be transferred onto an SiO2-coated silicon substrate, thereby allowing for realization of field-effect transistors after electrode deposition and thermal annealing. The transistor array exhibits spatial uniformity in electrical performance with an average hole mobility of ~0.002 cm2 V−1 s−1 and on/off ratio of 130. Furthermore, gate-induced modulation of the BP channel allows for enhancement in the photoresponsivity for 1550-nm light illumination up to 24 mA W−1, which benefits the application of the phototransistor array for near infrared imaging.

Abstract Inkjet printing is a cost-effective and scalable way to assemble colloidal materials into desired patterns in a vacuum- and lithography-free manner. Two-dimensional (2D) nanosheets are a promising material category for printed electronics because of their compatibility with solution processing for stable ink formulations as well as a wide range of electronic types from metal, semiconductor to insulator. Furthermore, their dangling bond-free surface enables atomically thin, electronically-active thin films with van der Waals contacts which significantly reduce the junction resistance. Here, we demonstrate all inkjet-printed thin-film transistors consisting of electrochemically exfoliated graphene, MoS2, and HfO2 as metallic electrodes, a semiconducting channel, and a high-k dielectric layer, respectively. In particular, the HfO2 dielectric layer is prepared via two-step; electrochemical exfoliation of semiconducting HfS2 followed by a thermal oxidation process to overcome the incompatibility of electrochemical exfoliation with insulating crystals. Consequently, all inkjet-printed 2D nanosheets with various electronic types enable high-performance, thin-film transistors which demonstrate field-effect mobilities and current on/off ratios of ~10 cm2 V−1 s−1 and >105, respectively, at low operating voltage.

The chalcogenides of p-block elements constitute a significant category of materials with substantial potential for advancing the field of electronic and optoelectronic devices. This is attributed to their exceptional characteristics, including elevated carrier mobility and the ability to fine-tune band gaps through solid solution formation. These compounds exhibit diverse structures, encompassing both three-dimensional and two-dimensional configurations, the latter exemplified by the compound In2Se3. Sesqui-chalcogenides were synthesized through the direct reaction of highly pure elements within a quartz ampoule. Their single-phase composition was confirmed using X-ray diffraction, and the morphology and chemical composition were characterized using scanning electron microscopy. The compositions of all six materials were also confirmed using X-ray photoelectron spectroscopy and Raman spectroscopy. This investigation delves into the thermodynamic properties of indium and gallium sesqui-chalcogenides. It involves low-temperature heat capacity measurements to evaluate standard entropies and Tian–Calvet calorimetry to elucidate the temperature dependence of heat capacity beyond the reference temperature of 298.15 K, as well as the enthalpy of formation assessed from DFT calculations.

Abstract The development of earth‐abundant electrocatalysts (ECs) operating at high current densities in water splitting electrolyzers is pivotal for the widespread use of the current green hydrogen production plants. Transition metal dichalcogenides (TMDs) have emerged as promising alternatives to the most efficient noble metal ECs, leading to a wealth of research. Some strategies based on material nanostructuring and hybridization, introduction of defects and chemical/physical modifications appeared as universal approaches to provide catalytic properties to TMDs, regardless of the specific material. In this work, we show that even a theoretically poorly catalytic (and poorly studied) TMD, namely zirconium diselenide (ZrSe2), can act as an efficient EC for the hydrogen evolution reaction (HER) when exfoliated in the form of two‐dimensional (2D) few‐layer flakes. We critically show the difficulties of explaining the catalytic mechanisms of the resulting ECs in the presence of complex structural and chemical modifications, which are nevertheless evaluated extensively. By doing so, we also highlight the easiness of transforming 2D TMDs into effective HER‐ECs. To strengthen our message in practical environments, we report ZrSe2‐based acidic (proton exchange membrane [PEM]) and alkaline water electrolyzers operating at 400 mA cm–2 at a voltage of 1.88 and 1.92 V, respectively, thus competing with commercial technologies.

In this work, germanene and its derivatives (Ge-H, Ge-CH3, Ge-C3-CN) were explored as electrochemical impedimetric platforms to develop a competitive immunoassay for the direct detection of gut-derived metabolites, kynurenic acid (KA) and quinolinic acid (QA). The competition occurs between the free KA/QA standards and BSA-conjugated antigens for a fixed amount of primary antibody binding sites. This affects the electron transfer rate of the [Fe(CN)6]3−/4− redox couple and changes the charge transfer resistance (Rct) on the electrode surface. The impedimetric signal measured due to the change in Rct is then correlated to the KA and QA concentration.

Abstract 2D metal monochalcogenides have recently attracted interest for photoelectrochemical (PEC) applications in aqueous electrolytes. Their optical bandgap in the visible and near‐infrared spectral region is adequate for energy conversion and photodetection/sensing. Their large surface‐to‐volume ratio guarantees that the charge carriers are photogenerated at the material/electrolyte interface, where redox reactions occur, minimizing recombination processes. However, solution‐processed photoelectrodes based on these materials exhibit energy conversion efficiencies that are far from the current state of the art expressed by established technologies. This work reports a systematic morphological, spectroscopic, and PEC characterization of solution‐processed films of photoactive InSe flakes for PEC‐type photodetectors. By optimizing the thickness and hybridizing InSe flakes with electrically conductive Sn:In2O3 (ITO) nanocrystals, photoanodes with a significant photoanodic response in both acidic and alkaline media are designed, reaching responsivity up to 60.0 mA W−1 (external quantum efficiency = 16.4%) at +0.4 V versus RHE under visible illumination. In addition, a strategy based on the use of sacrificial agents (i.e., 2‐propanol and Na2SO3) is proposed to improve the stability of the InSe and ITO/InSe photodetectors. Our data confirm the potential of 2D InSe for PEC energy conversion and sensing applications, remarking the challenges related to InSe stability during anodic operation.

The serendipitous chemical and physical properties of 2D materials (2DMs) have provoked enormous research efforts. These materials suggest an attractive podium for various optoelectronic, energy conversion, energy storage, and sensing device applications. The outstanding optical and electrical properties combined with superior mechanical characteristics make 2DMs an unprecedented choice for the diversity of advanced high‐efficient photodetectors. The functionalities and properties of such materials can further be tailored by combining 2DMs in the form of nanoarchitecture heterostructures. Thus, this study focuses on the recent advancements of 2D heterostructures for highly efficient photodetectors started with an introduction to their basic structural configurations. Then, a discussion on their state‐of‐the‐art synthesis methods is stressing the approaches that contrive the current margins and provide a path toward realizing these materials for efficient photodetector applications. The advanced characterization techniques that are useful for analyzing 2DM‐based photodetectors and underlying mechanisms for superior device performance are summarized systematically. Furthermore, utilization of 2DM‐based heterostructures for high‐performance photodetector applications with the special emphasis on different photodetection mechanisms is also discussed comprehensively at the end.

A two-dimensional (2D) Sb-modified screen-printed carbon nanofibers electrode (2D Sbexf-SPCNFE) was developed to improve the stripping voltammetric determination of Cd(II) and Pb(II), taking advantage of the synergistic effect between the two nanomaterials. The surface morphology of the 2D Sbexf-SPCNFE was investigated by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Raman spectroscopy. The analytical performance of 2D Sbexf-SPCNFE was compared to those presented by screen-printed carbon electrodes modified with 2D Sbexf (2D Sbexf-SPCE) and the corresponding bare electrodes: screen-printed carbon nanofibers electrode (SPCNFEbare) and screen-printed carbon electrode (SPCEbare). After optimizing the experimental conditions, the 2D Sbexf-SPCNFE exhibited much better analytical parameters compared to the other assessed sensors. Analysis in 0.01 mol L−1 HCl (pH = 2) using 2D Sbexf-SPCNFE showed excellent linear behavior in the concentration range of 2.9 to 85.0 µg L−1 and 0.3 to 82.0 µg L−1 for Cd(II) and Pb(II), respectively. The limits of detection after 240 s deposition time for Cd(II) and Pb(II) were 0.9 and 0.1 µg L−1, and sensitivities between 1.5 and 3 times higher than those displayed by SPCEbare, SPCNFEbare, and 2D Sbexf-SPCE were obtained. Finally, the 2D Sbexf-SPCNFE was successfully applied to the determination of Cd(II) and Pb(II) traces in a certified estuarine water sample.

In this study, novel flexible micro-scale humidity sensors were directly fabricated in graphene oxide (GO) and polyimide (PI) using ion beam writing without any further modifications, and then successfully tested in an atmospheric chamber. Two low fluences (3.75 × 1014 cm−2 and 5.625 × 1014 cm−2) of carbon ions with an energy of 5 MeV were used, and structural changes in the irradiated materials were expected. The shape and structure of prepared micro-sensors were studied using scanning electron microscopy (SEM). The structural and compositional changes in the irradiated area were characterized using micro-Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Rutherford back-scattering spectroscopy (RBS), energy-dispersive X-ray spectroscopy (EDS), and elastic recoil detection analysis (ERDA) spectroscopy. The sensing performance was tested at a relative humidity (RH) ranging from 5% to 60%, where the electrical conductivity of PI varied by three orders of magnitude, and the electrical capacitance of GO varied in the order of pico-farads. In addition, the PI sensor has proven long-term sensing stability in air. We demonstrated a novel method of ion micro-beam writing to prepare flexible micro-sensors that function over a wide range of humidity and have good sensitivity and great potential for widespread applications.

Magnetic metal–organic frameworks (MMOFs) are gaining increased attention as emerging adsorbents/water remediation agents. Herein, a facile development of novel MMOFs comprised of coated ferrite nanoparticles (MNPs) and UiO-66 metal–organic framework is reported. In specific, coated Co- and Zn-doped ferrite magnetic nanoparticles were synthesized as building block while the metal–organic framework was grown in the presence of MNPs via a semi-self-assembly approach. The utilization of coated MNPs facilitated the conjugation and stands as a novel strategy for fabricating MMOFs with increased stability and an explicit structure. MMOFs were isolated with 13–25 nm crystallites sizes, 244–332 m2/g specific surface area (SSA) and 22–42 emu/g saturation magnetization values. Establishing the UiO-66 framework via the reported semi-self-assembly resulted in roughly 70% reduction in both magnetic properties and SSA, compared with the initial MNPs building blocks and UiO-66 framework, respectively. Nonetheless, the remaining 30% of the magnetization and SSA was adequate for successful and sufficient adsorption of two different pesticides, 2,4-Dichlorophenoxyacetic acid (2,4-D) and 2,4,5-Trichlorophenoxyacetic acid (2,4,5-T), while the recovery with a commercial magnet and reuse were also found to be effective. Adsorption and kinetic studies for all three MMOFs and both pesticides were performed, and data were fitted to Langmuir–Freundlich isotherm models.

Mixed-matrix membranes (MMMs) possess the unique properties and inherent characteristics of their component polymer and inorganic fillers, or other possible types of additives. However, the successful fabrication of compact and defect-free MMMs with a homogeneous filler distribution poses a major challenge, due to poor filler/polymer compatibility. In this study, we use two-dimensional multi-layered Ti3C2Tx MXene nanofillers to improve the compatibility and CO2/CH4 separation performance of cellulose triacetate (CTA)-based MMMs. CTA-based MMMs with TiO2-based 1D (nanotubes) and 0D (nanofillers) additives were also fabricated and tested for comparison. The high thermal stability, compact homogeneous structure, and stable long-term CO2/CH4 separation performance of the CTA-2D samples suggest the potential application of the membrane in bio/natural gas separation. The best results were obtained for the CTA-2D sample with a loading of 3 wt.%, which exhibited a 5-fold increase in CO2 permeability and 2-fold increase in CO2/CH4 selectivity, compared with the pristine CTA membrane, approaching the state-of-the-art Robeson 2008 upper bound. The dimensional (shape) effect on separation performance was determined as 2D > 1D > 0D. The use of lamellar stacked MXene with abundant surface-terminating groups not only prevents the aggregation of particles but also enhances the CO2 adsorption properties and provides additional transport channels, resulting in improved CO2 permeability and CO2/CH4 selectivity.

The construction of flexible electrochemical devices for energy storage and generation is of utmost importance in modern society. In this article, we report on the synthesis of flexible MoS2-based composite paper by high-energy shear force milling and simple vacuum filtration. This composite material combines high flexibility, mechanical strength and good chemical stability. Chronopotentiometric charge–discharge measurements were used to determine the capacitance of our paper material. The highest capacitance achieved was 33 mF·cm−2 at a current density of 1 mA·cm−2, demonstrating potential application in supercapacitors. We further used the material as a cathode for the hydrogen evolution reaction (HER) with an onset potential of approximately −0.2 V vs RHE. The onset potential was even lower (approximately −0.1 V vs RHE) after treatment with n-butyllithium, suggesting the introduction of new active sites. Finally, a potential use in lithium ion batteries (LIB) was examined. Our material can be used directly without any binder, additive carbon or copper current collector and delivers specific capacity of 740 mA·h·g−1 at a current density of 0.1 A·g−1. After 40 cycles at this current density the material still reached a capacity retention of 91%. Our findings show that this composite material could find application in electrochemical energy storage and generation devices where high flexibility and mechanical strength are desired.

A multitude of strategies to alter the properties of graphene, a representative two-dimensional material, has been proposed with the aim of improving its performance and capabilities. Whilst in general doping with any element is reported in the literature as an electrochemistry enhancing process, there is no real reason for dopants to always be beneficial. Here we doped graphene with boron or nitrogen and show that they have completely opposite properties for electrochemical detection of 2,4,6-trinitrotoluene (TNT). Nitrogen-doped graphene enhances the signal of TNT, whereas boron-doped graphene reduces the response when compared to undoped graphene. This debunks most of the papers claiming that doping results in excellent electrochemistry.

Thanks to the unique properties of graphite oxides and graphene oxide (GO), this material has become one of the most promising materials that are widely studied. Graphene oxide is not only a precursor for the synthesis of thermally or chemically reduced graphene: researchers revealed a huge amount of unique optical, electronic, and chemical properties of graphene oxide for many different applications. In this review, we focus on the structure and characterization of GO, graphene derivatives prepared from GO and GO applications. We describe GO utilization in environmental applications, medical and biological applications, freestanding membranes, and various composite systems.

Copper selenide-sulfide nanostructures were synthesized using metal-organic chemical routes in the presence of Cu- and Se-precursors as well as S-containing compounds. Our goal was first to examine if the initial Cu/Se 1:1 molar proportion in the starting reagents would always lead to equiatomic composition in the final product, depending on other synthesis parameters which affect the reagents reactivity. Such reaction conditions were the types of precursors, surfactants and other reagents, as well as the synthesis temperature. The use of ‘hot-injection’ processes was avoided, focusing on ‘non-injection’ ones; that is, only heat-up protocols were employed, which have the advantage of simple operation and scalability. All reagents were mixed at room temperature followed by further heating to a selected high temperature. It was found that for samples with particles of bigger size and anisotropic shape the CuSe composition was favored, whereas particles with smaller size and spherical shape possessed a Cu2−xSe phase, especially when no sulfur was present. Apart from elemental Se, Al2Se3 was used as an efficient selenium source for the first time for the acquisition of copper selenide nanostructures. The use of dodecanethiol in the presence of trioctylphosphine and elemental Se promoted the incorporation of sulfur in the materials crystal lattice, leading to Cu-Se-S compositions. A variety of techniques were used to characterize the formed nanomaterials such as XRD, TEM, HRTEM, STEM-EDX, AFM and UV-Vis-NIR. Promising results, especially for thin anisotropic nanoplates for use as electrocatalysts in nitrogen reduction reaction (NRR), were obtained.

The study of the effects associated with the compatibility of the components of the hybrid filler with polymer matrix, which ultimately decide on achieving mixed matrix membranes (MMMs) with better gas separation properties, is essential. Herein, a facile solution casting process of simple incorporating CeO2@GO hybrid inorganic filler material is implemented. Significant improvements in material and physico-chemical properties of the synthesized membranes were observed by SEM, XRD, TGA, and stress-strain measurements. Usage of graphene oxide (GO) with polar groups on the surface enabled forming bonds with ceria (CeO2) nanoparticles and CTA polymer and provided the homogeneous dispersion of the nanofillers in the hybrid MMMs. Moreover, increasing GO loading concentration enhanced both gas permeation in MMMs and CO2 gas uptakes. The best performance was achieved by the membrane containing 7 wt.% of GO with CO2 permeability of 10.14 Barrer and CO2/CH4 selectivity 50.7. This increase in selectivity is almost fifteen folds higher than the CTA-CeO2 membrane sample, suggesting the detrimental effect of GO for enhancing the selectivity property of the MMMs. Hence, a favorable synergistic effect of CeO2@GO hybrid fillers on gas separation performance is observed, propounding the efficient and feasible strategy of using hybrid fillers in the membrane for the potential biogas upgrading process.

The hydrophilic and hydrophobic single-walled carbon nanotube membranes were prepared and progressively applied in sorption, filtration, and pertraction experiments with the aim of eliminating three antibiotics—tetracycline, sulfamethoxazole, and trimethoprim—as a single pollutant or as a mixture. The addition of SiO2 to the single-walled carbon nanotubes allowed a transparent study of the influence of porosity on the separation processes. The mild oxidation, increasing hydrophilicity, and reactivity of the single-walled carbon nanotube membranes with the pollutants were suitable for the filtration and sorption process, while non-oxidized materials with a hydrophobic layer were more appropriate for pertraction. The total pore volume increased with an increasing amount of SiO2 (from 743 to 1218 mm3/g) in the hydrophilic membranes. The hydrophobic layer completely covered the carbon nanotubes and SiO2 nanoparticles and provided significantly different membrane surface interactions with the antibiotics. Single-walled carbon nanotubes adsorbed the initial amount of antibiotics in less than 5 h. A time of 2.3 s was sufficient for the filtration of 98.8% of sulfamethoxazole, 95.5% of trimethoprim, and 87.0% of tetracycline. The thicker membranes demonstrate a higher adsorption capacity. However, the pertraction was slower than filtration, leading to total elimination of antibiotics (e.g., 3 days for tetracycline). The diffusion coefficient of the antibiotics varies between 0.7–2.7 × 10−10, depending on the addition of SiO2 in perfect agreement with the findings of the textural analysis and scanning electron microscopy observations. Similar to filtration, tetracycline is retained by the membranes more than sulfamethoxazole and trimethoprim.

Due to the high affinity of ceria (CeO2) towards carbon dioxide (CO2) and the high thermal and mechanical properties of cellulose triacetate (CTA) polymer, mixed-matrix CTA-CeO2 membranes were fabricated. A facile solution-casting method was used for the fabrication process. CeO2 nanoparticles at concentrations of 0.32, 0.64 and 0.9 wt.% were incorporated into the CTA matrix. The physico-chemical properties of the membranes were evaluated by SEM-EDS, XRD, FTIR, TGA, DSC and strain-stress analysis. Gas sorption and permeation affinity were evaluated using different single gases. The CTA-CeO2 (0.64) membrane matrix showed a high affinity towards CO2 sorption. Almost complete saturation of CeO2 nanoparticles with CO2 was observed, even at low pressure. Embedding CeO2 nanoparticles led to increased gas permeability compared to pristine CTA. The highest gas permeabilities were achieved with 0.64 wt.%, with a threefold increase in CO2 permeability as compared to pristine CTA membranes. Unwanted aggregation of the filler nanoparticles was observed at a 0.9 wt.% concentration of CeO2 and was reflected in decreased gas permeability compared to lower filler loadings with homogenous filler distributions. The determined gas selectivity was in the order CO2/CH4 > CO2/N2 > O2/N2 > H2/CO2 and suggests the potential of CTA-CeO2 membranes for CO2 separation in flue/biogas applications.

This work presents the gas separation evaluation of 6FDA-DAM:DABA (3:1) co-polyimide and its enhanced mixed matrix membranes (MMMs) with graphene oxide (GO) and ZIF-8 (particle size of 2:CH4 binary mixture at 2 bar feed pressure and 25 °C. The pristine 6FDA-copolyimide showed CO2 permeability (PCO2) of 147 Barrer and CO2/CH4 selectivity (αCO2/CH4) of 47.5. At the optimum GO loading (1 wt.%), the PCO2 and αCO2/CH4 were improved by 22% and 7%, respectively. A combination of GO (1 wt.%)/ZIF-8 fillers tremendously improves its PCO2; by 990% for GO/ZIF-8 (5 wt.%) and 1.124% for GO/ZIF-8 (10 wt.%). Regrettably, the MMMs lost their selectivity by 16–55% due to the non-selective filler-polymer interfacial voids. However, the hybrid MMM performances still resided close to the 2019 upper bound and showed good performance stability when tested at different feed pressure conditions.

This article has been retracted. Please see the Retraction Notice for more detail: https://doi.org/10.1038/s41467-020-19968-3.

Zero-valent metallic nanoparticles can exhibit superparamagnetism, due to quantum effects in magnetic nanomaterials, but their syntheses can be hindered by chemical instability. Here, the authors prepare air-stable superparamagnetic nanoparticles trapped between thermally reduced graphene oxide nanosheets.

The aim of this paper is to prepare and characterize partially-oxidized graphite oxide and consider if it is possible to affect the level of oxidation of particles by an adjustment of the oxidizing agent. Several samples were prepared, using different amounts of oxidizing agent. The samples were subsequently analyzed. The C/O ratio was evaluated from XPS, EDS, and EA. The amount and type of individual oxygen functionalities were characterized by XPS, Raman spectroscopy, and cyclic voltammetry. The structure was studied by SEM and XRD. Thermal stability was investigated by STA-MS in argon atmosphere. The results can be useful in order to design simple technology for graphite oxide synthesis with required oxygen content.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

In this contribution we present a growth of Ga1-xMnxN layers by MOVPE. Mn doped GaN layers were grown with and without undoped GaN templates on (0001) sapphire substrates in a quartz horizontal reactor. For the deposition of Ga1-xMnxN layers (MCp)2Mn was used as a Mn – precursor. The flow of the Mn precursor was 0.2-3.2 μmol.min-1. The deposition of Ga1-xMnxN layers was carried out under the pressure of 200 mbar, the temperature 1050 °C and the V/III ratio of 1360. For the growth of high quality GaN:Mn layers it was necessary to grow these layers on a minimally partially coalesced layer of pure GaN. The direct deposition of GaN:Mn layer on the low temperature GaN buffer layer led to a three-dimensional growth during the whole deposition process. Another investigated parameter was the influence of nitrogen on the layer’s properties. A nearly constant ferromagnetic moment persisting up to room temperature was observed on the synthesized thin films.

Presented experiments utilize methanolic solution of zinc acetyl-acetonate as a precursor and sapphire (001) as a substrate for deposition of thin films of ZnO. The X-ray diffraction analysis revealed polycrystalline character of prepared films with preferential growth orientation along c-axis. The roughness of prepared films was assessed by AFM microscopy and represented by roughness root mean square (RMS) value in range of 1.8 - 433 nm. The surface morphology was mapped by scanning electron microscopy showing periodical structure with several local defects. The optical transmittance spectrum of ZnO films was measured in wavelength range of 200-1000 nm. Prepared films are transparent in visible range with sharp ultra-violet cut-off at approximately 370 nm. Raman spectroscopy confirmed wurtzite structure and the presence of compressive stress within its structure as well as the occurrence of oxygen vacancies. The four-point Van der Pauw method was used to study the transport prosperities. The resistivity of presented ZnO films was found 8 × 10–2 Ω cm with carrier density of 1.3 × 1018 cm–3 and electron mobility of 40 cm2 V–1 s–1.