Molybdenum disulfide (MoS2) is well-known for its broad range of applications, including its use in electronic devices. This manuscript focuses on the investigation of room temperature magnetron sputtered MoS2 with a main topic on its physical and chemical properties. The deposition process employed radio frequency magnetron sputtering method with a deposition power of 7-50 W. Structural investigations were performed using SEM, TEM, XRD and Raman spectroscopy. In this instance, correlation was identified between surface morphology, sputter power, and film thickness. The presence of both horizontally aligned and vertically aligned areas of molecular arrangement was identified and varied at the surface with deposition power and thickness. At low power, vertically aligned MoS2, referred to as nanowalls, could be detected, while at 50 W only a smooth surface with horizontal aligned grains could be observed. Additional tensile stress was observed in the material. The chemical analysis, conducted using XPS and EDS, investigated the surface composition and oxygen content of MoS2 over the course of its storage in ambient atmosphere after deposition. The surface of the thin films exhibited a greater tendency for oxidation compared to the bulk. A surface formation of MoSxOy is assumed with a higher oxygen ratio at 50 W compared to 7 W deposited films, because of a higher defect density at higher sputter power which support the oxidation. In the context of 50 W films, a wafer-scale process of vertical electronic devices is demonstrated, in which MoS2 is fully encapsulated with SiO2. The devices exhibit capacitive behavior.

Two-dimensional (2D) materials, in particular transition metal dichalcogenides (TMDCs), have been recognized as material class with great potential for future electronic devices. However, to realize the potential of these materials, technology processes are needed that allow wafer-scale fabrication to integrate 2D materials into electronic devices. This paper presents such technology. A wafer-scale sputter deposition process of MoS2 is presented, which enables a homogeneous coating of SiO2 wafers. Based on this process, a technology is presented that allows the fabrication of two-terminal devices of different area dimensions at wafer scale. As a critical technological step, the passivation of the MoS2 layer, in particular, is examined more closely by means of automated electrical measurements at wafer level and chemical–structural investigations using scanning transmission electron microscopy (STEM), among others. We show that the electronic properties of devices with insufficient passivation change significantly. Thus, a protection of the MoS2 layer during fabrication and for the final operation is of particular importance. By taking this into account, the here designed device technology shows a way to integrate 2D materials into future microelectronic systems.

2D nanomaterials are proposed as promising photothermal materials for interfacial photothermal water evaporation. However, low evaporation efficiency, the use of hazardous hydrofluoric solution, and poor stability severely limit their practical applications. Here, a mixed solvent exfoliation surface deposition (MSESD) strategy for the preparation of NiPS 3 nanosheets and NiPS 3 /polyvinyl alcohol (PVA) converter is successfully developed. The converter is obtained by drop‐casting the NiPS 3 /PVA nanosheets onto a sponge. The PVA is mainly deposited on the edge of NiPS 3 nanosheets, which not only improves the stability of NiPS 3 nanosheets, but also adheres to the sponge to prepare a 3D photothermal converter, which shows an evaporation rate of 1.48 kg m −2 h −1 and the average photothermal conversion efficiency (PTCE) of 93.5% under a light intensity of 1 kW m −2 . The photothermal conversion mechanism reveals that the energy of absorbed photons in NiPS 3 nanosheets can be effectively converted into heat through non‐radiative photon transitions as well as multiple optical interactions. To the best of the knowledge, this is the first report on the application of 2D metal‐phosphorus‐chalcogen (MPCh x ) for solar desalination, which provides new insights and guidance for the development of high‐performance 2D photothermal materials.

Selective and complete micro-patterning (mu-patterning) of alpha-titanium surfaces were performed using a 1064 nm laser system. With a fluence of 0.6 J center dot cm-2 and a pulse duration of 10 ps, two different mu-patterns of laser induced periodic surface structures (LIPSS) were generated by mainly changing the number of pulses per spot and the spot-to-spot distance. A high number of pulses per spot and a large spot-to-spot distance of 60 mu m gives selectively with LIPSS modified dimples. Their spatial period varies from 159 nm to a maximum of 620 nm inside the dimples. An increased fraction of TiO2 in the crystalline form of rutile gave improved wear resistance and a coefficient of friction COF of 0.20 +/- 0.02. If the spot-to-spot distance is reduced to 6 mu m and the number of pulses at one spot remains low, a completely rippled surface with slightly increased oxide fraction but still a metallic plastic behaviour was able to show volume expansion during sliding. The observed self-healing ability of this LIPSS pattern is correlated with the relief of compressive stresses in this study. As volume expansion operates against the sliding motion of the diamond tip, high COFs of 0.62 +/- 0.11 for a normal load of 1.0 N and 0.45 +/- 0.04 for a normal load of 0.5 N were measured. After further optimisation, such a tailored increase in COF and load stimulated volume expansion of the surface could be useful in order to act against implant loosening and undesired movements.

Angewandte ChemieVolume 135, Issue 17 e202381711 Graphisches InhaltsverzeichnisFree Access Graphisches Inhaltsverzeichnis: Angew. Chem. 17/2023 First published: 05 April 2023 https://doi.org/10.1002/ange.202381711AboutPDF ToolsRequest permissionAdd to favorites ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat Volume135, Issue17April 17, 2023e202381711 This is the German version of Angewandte Chemie. Note for articles published since 1962: Do not cite this version alone. Take me to the International Edition version with citable page numbers, DOI, and citation export. We apologize for the inconvenience. RelatedInformation

This article reports a new approach toward fabrication and directed assembly of nanoparticulate reactive system (Nanofoils) on patterned substrates. Different from current state-of-the-art, gas phase electrodeposition uses nanoparticles instead of atoms to form densely packed multilayered thin films at room temperature-pressure. On ignition, the multilayer system undergoes an exothermic self-propagating reaction. The numerous contact points between two metallic nanoparticulate layers aid in high heat release. Sub-10-nm Platinum (Pt) and Aluminum (Al) particles are synthesized through cathode erosion of metal electrodes in a flow of pure nitrogen gas (spark ablation). Pt/Al bilayer stacks with total thickness of 3–8 µm undergo self-propagating reaction with a 10.3 mm s −1 wavefront velocity on local ignition. The reaction wavefront is captured using high speed videography. Calorimetry studies reveal two exothermic peaks suggesting Pt/Al alloy formation. The peak at 135 °C has a higher calorific value of 150 mW g −1 while the peak at 400 °C has a 12 mW g −1 exothermic peak. X-ray diffraction study shows reaction-products are cubic Al 2 Pt with small quantities of orthorhombic Al 6 Pt and orthorhombic AlPt 2 . Electron microscopy studies help draw a correlation between film morphology, bimetallic interface, nanoparticle oxidation, and self-propagating reaction kinetics that is significant in broadening our understanding towards nanoparticulate reactive systems.

Photoelectrochemical (PEC) water splitting requires stable, efficient, and cost‐effective photoelectrodes to enable future large‐scale solar hydrogen production. Ultrathin hematite‐hercynite photoanodes that meet all these criteria in an excellent way is presented here. Hematite‐hercynite photoelectrodes are synthesized in a self‐forming manner by thermal oxidation of iron–aluminum alloy films and characterized with regard to water splitting applications. Photoanodes fabricated from 17 wt.% Al at 493 °C for 8 h and 685 °C for 5 min exhibit, for instance, a photocurrent density of 1.24 and 1.53 mA cm −2 at 1.23 V versus RHE, respectively, as well as superior light absorption in the visible range of the solar spectrum. The PEC performance improvement in comparison to pure hematite thin film electrodes is first achieved by adjusting the aluminum concentration with an optimum range of 12–17 wt.% and second by optimizing the annealing conditions. The resulting photocurrent densities are about a factor of three higher than those obtained from electrodes synthesized from pure iron thin films using the same synthesis conditions. Finally, it is shown that ultrathin hematite‐hercynite photoelectrodes enable even unassisted solar water splitting in a NaOH (1 m ) electrolyte with a maximum solar‐to‐hydrogen conversion efficiency of 0.78%.

This article reports a new approach toward fabrication and directed assembly of nanoparticulate reactive system (Nanofoils) on patterned substrates. Different from current state-of-the-art, gas phase electrodeposition uses nanoparticles instead of atoms to form densely packed multilayered thin films at room temperature-pressure. On ignition, the multilayer system undergoes an exothermic self-propagating reaction. The numerous contact points between two metallic nanoparticulate layers aid in high heat release. Sub-10-nm Platinum (Pt) and Aluminum (Al) particles are synthesized through cathode erosion of metal electrodes in a flow of pure nitrogen gas (spark ablation). Pt/Al bilayer stacks with total thickness of 3-8 & mu;m undergo self-propagating reaction with a 10.3 mm s(-1) wavefront velocity on local ignition. The reaction wavefront is captured using high speed videography. Calorimetry studies reveal two exothermic peaks suggesting Pt/Al alloy formation. The peak at 135 & DEG;C has a higher calorific value of 150 mW g(-1) while the peak at 400 & DEG;C has a 12 mW g(-1) exothermic peak. X-ray diffraction study shows reaction-products are cubic Al2Pt with small quantities of orthorhombic Al6Pt and orthorhombic AlPt2. Electron microscopy studies help draw a correlation between film morphology, bimetallic interface, nanoparticle oxidation, and self-propagating reaction kinetics that is significant in broadening our understanding towards nanoparticulate reactive systems.

Graphical Abstract Electrocatalytic carbon dioxide reduction (CO2 ECR) over metal phosphorous trichalcogenide (MPCh3) nanosheets was systematically investigated by Dong Wang, Chen Shen, Dan Ren, Hongguang Wang, and co-workers in their Research Article (e202217253). Unlike the layered CoPS3 and NiPS3 nanosheets, the active Sn atoms tend to be exposed on the surfaces of nonlayered SnPS3 nanosheets, which exhibit clearly improved formic acid selectivity.

Two-dimensional (2D) materials catalysts provide an atomic-scale view on a fascinating arena for understanding the mechanism of electrocatalytic carbon dioxide reduction (CO2 ECR). Here, we successfully exfoliated both layered and nonlayered ultra-thin metal phosphorous trichalcogenides (MPCh(3)) nanosheets via wet grinding exfoliation (WGE), and systematically investigated the mechanism of MPCh(3) as catalysts for CO2 ECR. Unlike the layered CoPS3 and NiPS3 nanosheets, the active Sn atoms tend to be exposed on the surfaces of nonlayered SnPS3 nanosheets. Correspondingly, the nonlayered SnPS3 nanosheets exhibit clearly improved catalytic activity, showing formic acid selectivity up to 31.6 % with -7.51 mA cm(-2) at -0.65 V vs. RHE. The enhanced catalytic performance can be attributed to the formation of HCOO* via the first proton-electron pair addition on the SnPS3 surface. These results provide a new avenue to understand the novel CO2 ECR mechanism of Sn-based and MPCh(3)-based catalysts.

In this work we evaluate the role of a-SiC:H(p)/SiO2 localized surface states (SS) in the Photoelectrochemical Water Splitting reaction. The analysis was carried out in three steps. First, retrieving the a-SiC:H(p) SS, energy distribution and density, by Electrochemical Impedance Spectroscopy techniques. Second, relating these results with direct measurements over the a-SiC:H(p)/SiO2 surface using X-ray Photoelectron spectroscopy. Finally, assessing the SS influence in the photo-induced hydrogen reduction by testing the a-SiC:H(p) photocathode with Linear Sweep Voltammetry. The whole analysis was done after subjecting the a-SiC:H(p) surface to different annealing treatments, i.e. 600 degrees C and 700 degrees C, necessary to obtain the required ohmic contacts. We believe that the participation of SS in an indirect electron charge transfer to the electrolyte, is kinetically feasible to take place in an a-SiC:H surface with relatively low SS density, similar to 0.3x10(12) cm(-2). Whilst higher SS densities, in the range of similar to 1.48x10(14) cm(-2), would trigger undesired charge carrier recombination.

Nano-structuring enables us to add additional degrees of freedom to the design of optical elements. Especially the possibility of controlling the polarization is of great interest in the field of nano-structured optics. For being able to exploit the whole range of form-birefringent phase shifts, the aspect ratios of the resulting element are typically much higher than the aspect ratios of conventional diffractive optical elements (DOEs), which does not only pose a challenge on fabrication but also on characterization. We evaluate several well-established approaches for the nondestructive characterization, including Müller-Matrix-Ellipsometry, measurement of the diffraction efficiencies, scattering measurements and calibration with rigorous coupled-wave modelling. The goal is to understand the challenges with all these techniques and combine them to a reliable method for structural reconnaisance of high aspect ratio nanostructures.

Solid solutions of the (1-x)(0.94Bi(0.5)Na(0.5)TiO(3)-0.06BaTiO(3))-xCaZrO(3) system are regarded as promising dielectrics for high-temperature capacitors as they exhibit a remarkable flat trend of the permittivity over a large temperature range coupled with comparable low dielectric losses. In this work, the composition 0.8 (0.94Bi(0.5)Na(0.5)TiO(3)-0.06BaTiO(3))-0.2CaZrO(3) was chosen in an attempt to optimize especially the high temperature dielectric properties above 200 degrees C. In particular, the influence of excess bismuth to account for element losses caused by evaporation, and the effect of manganese as acceptor dopant are reported. Conventional solid-state reaction route was used to synthesize selected compositions. X-ray diffraction was used to confirm a pseudo-cubic perovskite main phase in all examined compositions, although small traces of a zirconia secondary phase were also detected. All samples exhibit an expected flat trend of the relative permittivity with a maximum deviation of the permittivity lower than 15% between -80 degrees C and 300 degrees C. The unmodified base composition shows small dielectric loss (<2%) between -55 degrees C and 265 degrees C. By using small quantities of manganese doping, the small-loss temperature range was extended (-70 degrees C and 300 degrees C). Excess bismuth also affects the temperature-dependent dielectric losses, resulting in a narrowed temperature range, eventually limiting the application possibilities.

Memristive devices have led to an increased interest in neuromorphic systems. However, different device requirements are needed for the multitude of computation schemes used there. While linear and time-independent conductance modulation is required for machine learning, non-linear and time-dependent properties are necessary for neurobiologically realistic learning schemes. In this context, an adaptation of the resistance switching characteristic is necessary with regard to the desired application. Recently, bi-layer oxide memristive systems have proven to be a suitable device structure for this purpose, as they combine the possibility of a tailored memristive characteristic with low power consumption and uniformity of the device performance. However, this requires technological solutions that allow for precise adjustment of layer thicknesses, defect densities in the oxide layers, and suitable area sizes of the active part of the devices. For this purpose, we have investigated the bi-layer oxide system TiN/TiO x /HfO x /Au with respect to tailored I-V non-linearity, the number of resistance states, electroforming, and operating voltages. Therefore, a 4-inch full device wafer process was used. This process allows a systematic investigation, i.e., the variation of physical device parameters across the wafer as well as a statistical evaluation of the electrical properties with regard to the variability from device to device and from cycle to cycle. For the investigation, the thickness of the HfO x layer was varied between 2 and 8 nm, and the size of the active area of devices was changed between 100 and 2,500 µm2. Furthermore, the influence of the HfO x deposition condition was investigated, which influences the conduction mechanisms from a volume-based, filamentary to an interface-based resistive switching mechanism. Our experimental results are supported by numerical simulations that show the contribution of the HfO x film in the bi-layer memristive system and guide the development of a targeting device.

An automated flow rate program was applied for the synthesis of gold nanorods of different aspect ratios dependent on a two-dimensional concentration space of reducing agent and additional silver ions. It was found a regular redshift of the spectral position of the electromagnetic in-axis resonance of metal nanorods with decreasing concentration of reducing agent and increasing concentration of silver ions. The increase of resonance wavelength is strongly correlated with the aspect ratio of the formed nanorods. The experimental results agree with an electrostatic model of self-polarization due to positive excess charge of the nanorods in the presence of CTAB and confirm the crucial role of electrostatic control in the formation of nonspherical and composed nanoparticles in general.

Non-spherical Au/Ag nanoparticles can be generated by chemical reduction of silver ions in the presence of preformed gold nanoparticles. The process of particle formation can be controlled by concentrations of ligands and reducing agent. The formation of ellipsoidal, nanorod- and peanut-shaped nanoparticles as well as of more complex fractal nanoassemblies can be explained by changes in particle surface state, electrochemical potential formation and particle-internal self-polarization effects. It is possible to create highly fractal nanoassemblies with sizes between the mid-nanometer and the lower micrometer range. The assemblies are marked by high optical absorption and complex nano-networks of very high surface-to-volume ratios and a granular base structure.

The Front Cover shows an overlay of an image of a metal nanoparticle network (blue) and sets of non-spherical metal nanoparticles of different shapes (yellow). Beside networks, ellipsoidal, dumbbell-like, astragal-like and branched particles are formed. The character of these particles can be controlled by modulating particle/particle interaction by concentration of ligands and reducing agents during the reductive deposition of silver on preformed gold nanoparticles. An electrochemical open-circuit mixed electrode concept is used for explaining the behavior of nanoparticles during metal deposition, particle assembling and particle growth. The particles are of interest for so-called plasmonic labelling, nanoparticle-based SERS-sensing and heterogeneous catalysis. More information can be found in the Full Paper by J. M. Köhler et al. on page 1369 in Issue 12, 2019 (DOI: 10.1002/open.201900231).

Boron-doped multi-walled carbon nanotubes (B-MWCNTs) were synthesized, treated with hydrochloric acid, "piranha" solution, and decorated with gold nanoparticles (AuNPs). B-MWCNTs were characterized using Raman spectroscopy, scanning electron-and transmission electron microscopy, and electrochemical techniques. The results exhibit enhanced response and sensitivity of B-MWCNTs upon modification with AuNPs. Analysis of dopamine (DA) and epinephrine (EP) in presence of uric acid (UA) was investigated on B-MWCNTs/AuNPs in pig blood serum. Limits of detection of 0.20 and 0.30 mu M were estimated for DA and EP, respectively. The findings demonstrate that B-MWCNTs/AuNPs is proper for analysis of DA and EP under coexistence of UA.

Noble metal nanoparticles—especially shape anisotropic particles—have pronounced resonances in the optical spectrum. These sensitive absorption modes attract great interest in various fields of application. For nonspherical particles, no analytic description of the absorption spectra according to the commonly used Mie theory is possible. In this work, we present a semi-empirical approach for the explanation of the optical spectra of shape anisotropic particles such as silver nanoprisms and gold nanorods. We found an interpretation of the optical absorption spectra which is based on a single-photon-single-electron transition. This model is in a better agreement with the basic assumptions of quantum mechanics than the electrodynamic model of a localized surface plasmon excitation. Based on microfluidically obtained Ag nanoprisms and Au nanorods with very high ensemble homogeneities, dependencies between the geometrical properties of the shape anisotropic noble metal nanoparticles and the spectral position of the longitudinal absorption mode could be derived, which show that the assumption of a composed relative permittivity and the inclusion of the Rydberg constant is sufficient to describe the optical properties of the shape anisotropic particles. Within the scope of the measuring accuracy, the calculations furthermore lead to the value of the refractive index of the particle-surrounding medium.

The growth and aggregation behavior of metal nanoparticles can be modulated by surfactants and different other additives. Here the concept of how open-circuit mixed electrodes helps to understand the electrical aspects of nanoparticle growth and the consequences for the particle geometries is discussed. A key issue is the self-polarization effect of non-spherical metal nanoparticles, which causes a local decoupling of anodic and partial processes and asymmetry in the local rates of metal deposition. These asymmetries can contribute to deciding to the growth of particles with high aspect ratios. The interpretation of electrochemical reasons for particle growth and behavior is supported by experimental results of nanoparticle syntheses supported by microfluidics which can supply high yields of non-spherical nanoparticles and colloidal product solutions of high homogeneity.