Due to the special crystal structures and electron configurations, high-entropy alloys (HEAs) are expected to have favorable activities for electrocatalytic reactions. In this paper, a set of oxygen evolution reaction (OER) criteria are applied for the HEA-based electrocatalyst design. Specifically, FeNiMnCrCu HEA is predicted to have a better OER performance than the baseline FeCoNiCrAl HEA. To demonstrate this design approach, both FeNiMnCrCu and FeCoNiCrAl samples are prepared and tested. Their crystal structures and electrocatalytic performance are examined. This paper demonstrates the potential of using finely tuned HEAs for OER applications.

Catalytic processes are critical steps in numerous industrial processes. The discovery of high reactivity of defects in metal-free two-dimensional materials has bolstered their emergence as catalysts. Here we consider the effect of defect-inducing methods in hexagonal boron nitride (h-BN) on their performance for olefin and CO2 hydrogenation. We compare the changes introduced by ball milling and heat treatment in h-BN and show how varying the treatment conditions can impact the properties. We provide some evidence of the reactivity of the powders. Our results highlight how characterization can be exploited to assess the potential catalytic activity of h-BN for heterogeneous catalysis.

Direct arylation polycondensation (DArP) is an emerging synthetic method of producing conjugated polymers in an environmentally benign and cost-effective manner. We now report the synthesis of hole-transporting conjugated polymers, namely, DPP-OMe (Mn = 7.9 kg/mol) and DPP-F (Mn = 12.6 kg/mol), under microwave-assisted DArP conditions. These two polymers and the previously synthesized 3,6-Cbz-EDOT were evaluated as hole-transporting materials in mesoscopic perovskite solar cells. 3,6-Cbz-EDOT synthesized by DArP exhibited higher hole mobility and better photovoltaic properties than that synthesized by the Stille polycondensation. Moreover, chemical dopants improved the short-circuit current density (Jsc) and fill factor.

The strength of materials exhibits size effects at sample dimensions <1 mm. In the literature, two trends are identified in the length scale spectrum: smaller is stronger at <10 µm; larger is stronger at >500 µm. The dimension at which the transition between these two trends occurs remained unclear. We study this mesoscopic scale (20–400 µm) by examining the compression response of ring and pillar-shaped Al specimens. Integrating present results with literature data, we provide Al's compression response in a “master curve” fashion. We demonstrate the inadequacies of the classical surface layer model, and suggest directions for future studies.

Here we report a new type of n-type flexible film with a double-layer structure fabricated by hybridizing an n-type inorganic thermoelectric material, bismuth selenide (Bi2Se3), and an ordinary insulating polymer, poly(vinyl alcohol) (PVA). Flake-shaped Bi2Se3 nanoparticles (Bi2Se3 nanoflakes) modified with/without gold (Au) nanoparticles were distributed in the one side of PVA film with the particular arrangement, and the hybrid film showed a high Seebeck coefficient (−91 µV/K at room temperature) as an n-type flexible material. Our method is expected to be used for the design of flexible functional devices such as flexible thermoelectric modules.

A model is developed and implemented for load-controlled instrumented conical indentation of a brittle open-cell foam on a dense substrate. A survey of observations suggests that such indentations are typified by displacement excursions at small indentation loads, load-displacement variability, localized crushing, and a discrete to continuum transition at intermediate loads. The model includes all these effects as well as stiffening at large loads as the substrate is encountered. Direct quantitative comparison is made with measurements of a silica foam on a soda-lime glass substrate, strongly supporting the physical basis of the model.

This study constitutes an attempt to characterize the microscopic strain distribution during bending in the AI6156-T61 aged alloy and in the same aluminum alloy with nickel coating. Bendability was detected in both groups by load-displacement curves, at four different strain rates (0.5, 2, 5, and 10 mm/min). In the case of the bare aluminum alloy, the terminal bending angle (without fracture occurring) was 83°. It can be suggested that hemming effect, delamination, spallation, and falling back of the coating was evident in both regions. The surface morphology of the alloys under examination was studied using a scanning electron microscope connected to an energy-dispersive spectroscope.

A transmission surface plasmon resonance image (TSPRi) obtained with a plasmonic grating structure was investigated in combination with a smartphone camera. A substrate of a gold-coated CYTOP grating/glass slide showed the TSPR excitation wavelength of 675 nm at the incident light angle of 30°. The TSPRi acquired from a smartphone camera assembled with liquid crystal tunable filters corresponded with spectroscopic results. The sensitivity of this technique was 282/RIU. Due to changes in the sensitivity of the TSPRi intensity to the refractive index of the environment, this technique can be further developed for portable devices for sensor applications.

Lithium (Li) dendrite formation in Li-metal batteries (LMBs) remains a key obstacle preventing LMBs from their widespread application. This study focuses on the role of the stress field in the Li electrodeposits formation and growth. Coupled electrochemical and mechanical phase-field model (PFM) is used to investigate electrodeposited Li evolution under different conditions. The PFM results, using both the anisotropic elastic properties of Li and the random delivery of Li-ions through the solid electrolyte interface, show a significant local stress development indicating a direct correlation between the stress field and the origin of the undesired Li filaments initiation.

Thermoelectric (TE) is a heat-to-electricity energy conversion method with increasing attention. In recent years, novel highly efficient TE materials, including GeTe and other IV–VI based alloys, were reported, mainly due to either electronic optimization of transport properties or nanostructuring for minimization of the lattice thermal conductivity. Yet, the mechanical properties of such materials (with brittle nature), which are significant for obtaining the required durability under the associated thermo-mechanical conditions of practical applications, were much less tackled. The challenge is combining the both, upon introducing alloying elements, positively contributing both the TE figure of merit and the mechanical durability. In the current research, the TE and mechanical (mainly compression and fracture toughness) effects of Ag- and Cu-doping of the GeTe-rich (GeTe)0.96(Bi2Te3)0.04 alloy were investigated, suggesting improvement on both aspects.

Vertically aligned nitrogen-doped nanocrystalline diamond nanorods are fabricated from nitrogen-doped nanocrystalline diamond films using reactive ion etching in oxygen plasma. These nanorods show enhanced thermionic electron emission (TEE) characteristics, viz., a high current density of 12.0 mA/cm2 and a work function value of 4.5 eV with an applied voltage of 3 V at 923 K. The enhanced TEE characteristics of these nanorods are ascribed to the induction of nanographitic phases at the grain boundaries and the field penetration effect through the local field enhancement from nanorods owing to a high aspect ratio and an excellent field enhancement factor.

Energy-filtered transmission electron microscopy provides an opportunity to map the nanoscale elemental composition in polymeric systems. Nevertheless, it presents its own set of unique challenges in its application to soft materials. Here, we outline an optimized protocol for elemental mapping in soft materials using sulfur mapping of polymer/fullerene mixtures as an example. Three factors are crucial: (1) focusing at zero-loss, (2) using an objective aperture, and (3) maximizing signal-to-noise and counts for the chosen imaging conditions. Analyzing the corresponding source images, bright field images, and thickness maps can ensure optimum conditions are achieved for elemental mapping of polymers.

Several structure–property relationships are reported in large-area MoS2 thin films to understand the effect of sulfur vacancies along with complementary first-principles calculations. X-ray diffraction and reflectivity measurements demonstrated that sputtered MoS2 followed by a high-temperature sulfurization produced sharp film–substrate interface along with high crystalline order. Spectroscopic and transport measurements showed that removal of sulfur vacancies promoted A–B excitons, strong in-plane Raman modes, a sharp increase in dc resistivity, and strong photo-conducting behavior. We have clearly demonstrated that a hybrid method using magnetron sputtering can provide high-quality few-layer transition metal dichalcogenide films.

A thermo-pH sensitive graft copolymer was successfully obtained by grafting 4-vinylpyridine and N-vinylcaprolactam onto silicone rubber ((SR-g-4VP)-g-NVCL)) in two-step using ionizing radiation as an initiator. Factors such as dose and monomer concentration remarkably affected the grafting yield. Surface grafted films were well characterized by means of infrared-attenuated total reflection, carbon-13 nuclear magnetic resonance, thermogravimetric analysis, and mechanical properties were also studied. Scanning electron microscopy demonstrated that the grafting was superficial; mechanical studies demonstrated that grafting caused loss elongation of SR films. The grafted films showed a critical pH close to physiological pH and a critical temperature (lower critical solution temperature) about 35 °C, therefore, this material presents potential biomedical applications as drug delivery.

In this study, we have investigated electron field emission (EFE) characteristics of Q-carbon at room temperature and above. At room temperature the Q-carbon requires only ~2.4 V/μm electric field to turn-on the EFE. The EFE properties of the Q-carbon composite structure improve with temperature by lowering the turn-on field and increasing the current density. At 500 K we observed a turn-on field of ~2.34 V/μm, and a maximum current density was found to be ~53 µA/cm2 at 2.66 V/μm. The Q-carbon field emitters also show very stable EFE characteristics (within 7% fluctuations) over time for current intensities between 7.5 and 47 µA/cm2.

Si-TiN alloys are attractive for use as negative electrodes in Li-ion cells because of the high conductivity, low electrolyte reactivity, and thermal stability of TiN. Here it is shown that Si-TiN alloys with high Si content can surprisingly be made by simply ball milling Si and Ti powders in N2(g); a reaction not predicted by thermodynamics. This offers a low-cost and simple method of synthesizing these attractive materials. The resulting alloys have smaller grain sizes than Si-TiN made by ball milling Si and TiN directly, giving them high thermal stability and improved cycling characteristics in Li cells.

Among the commercially common transparent conducting oxides (TCOs) are fluorine-doped tin oxide (FTO) and indium-doped tin oxide (ITO), neither of which meets all criteria for the optimal TCO. Despite its superior chemical stability and being composed of abundant elements, FTO suffers from high surface roughness compared to ITO. Here, we introduce a path to substantially decrease the surface roughness of FTO, while preserving most of its original advantages, by depositing an SnO2 coating on top of the FTO layer using pulsed laser deposition. Such an enhancement may allow future use of FTO in devices that use now the more expensive, less stable ITO, which contains relatively rare indium.

Effective modification of existing supported catalyst has attracted plenty of interests recently. Herein, we introduced ultrasonication to synthesize the palladium-loaded cobalt-based zeolitic imidazolate framework and compared its properties with those using the conventional method. Remarkably, the ultrasonicated frameworks possess 15.33% higher of Brunauer–Emmett–Teller (BET) surface area and 63.37% higher of t-plot external surface area, respectively, which lead up to 23% rise in the degradation of organic pollutants under optimized conditions. Characterizations clearly revealed the causality between ultrasonication, morphology, and catalytic performance compared with their non-ultrasonicated counterparts which further demonstrates a simple but useful method for the modification of supported catalysts.

This paper explores thin films of the entropy-stabilized oxide (ESO) composition MgxNixCoxCuxZnxScxO (x ~ 0.167) grown by laser ablation in incremental gas pressures and O2/Ar ratios to modulate particle kinetic energy and plume reactivity. Low pressures supporting high kinetic energy adatoms favor the kinetic stabilization of a single rocksalt phase, while high pressures (low kinetic energy adatoms) result in phase separation. The pressure threshold for phase separation is a function of O2/Ar ratio. These findings suggest large kinetic energies facilitate the assembly and quench of metastable ESO phases that may require immoderate physical or chemical conditions to synthesize using near-equilibrium techniques.