Tunable Physical Properties Research Articles

Anti–oxidant and anti-inflammation activities of nanostructured assemblies of silver sulfide nanoparticles using an extract of Cinnamomum tamala leaves

Silver sulfide nanoparticles have gained applications in industrial areas due to their tunable physical, chemical, and biological properties. Among various nanoparticles silver sulfide nanoparticles have gained worldwide attention due to their assessment as an anti-microbial agent. The microstructure of nanostructured silver sulfide nanoparticles determine its electronic, structural, optical and electrical properties, and possible applications of silver sulfide nanoparticles in modern electronics, biology and medicine. The appearance of nonstoichiometry in silver sub-lattices of monoclinic silver sulfide at decreasing size particles to the nanometer scale is considered. The interdependent changes in non-stoichiometry and crystal structure at the transformation of a non- conducting nano crystalline silver sulfide in super-ionic conductors are also very important aspects in biosynthesis of Silver sulfide nanoparticles. The effect of nano crystalline state on the peculiarities of crystal structure, non-stoichiometry, optical and thermal properties of bio synthesized Silver sulfide nanoparticles are explained. Silver sulfide nanoparticle have provide a significant role in the biomedical field for various application- oriented products such as IR cameras, solar panels, optical fiber and filters. Among modern biomedical potential of silver sulfide nanoparticles tremendous interest is oriented towards the therapeutically enhanced personalized health care practices. The biosynthesized silver sulfide nanoparticle using aqueous extract of Cinnamomum leaves has been documented in our present research work. The presence of secondary metabolites like flavonoid, tannins, steroid, cardiac glycosides, and alkaloids was confirmed by phytochemical analyses of the aqueous extract of Cinnamomum tamala leaves and these secondary metabolites can be used as reducing stabilizing and capping agent. After three months, the biosynthesized Silver sulfide nanoparticles were found to be stable without the evidence of agglomeration at room temperature. Structural and morphological properties of Silver sulfide nanoparticles were analyzed by UV-VIS, FT-IR, XRD, EDX, TEM, and SEM spectroscopic techniques. The surface Plasmon resonance for Silver sulfide nanoparticles was obtained around 290nm. Biosynthesized Silver sulfide nanoparticles was spherical in shape with effective diameter size of 50nm.Our novel approach provides a promising and effective method to large scale synthesis of eco-friendly, and cost effective pharmacologically active silver sulfide nano particles.

Nanomaterial-Based Scaffolds for Tissue Engineering Applications: A Review on Graphene, Carbon Nanotubes and Nanocellulose.

Nanoscale biomaterials have garnered immense interest in the scientific community in the recent decade. This review specifically focuses on the application of three nanomaterials, i.e., graphene and its derivatives (graphene oxide, reduced graphene oxide), carbon nanotubes (CNTs) and nanocellulose (cellulose nanocrystals or CNCs and cellulose nanofibers or CNFs), in regenerating different types of tissues, including skin, cartilage, nerve, muscle and bone. Their excellent inherent (and tunable) physical, chemical, mechanical, electrical, thermal and optical properties make them suitable for a wide range of biomedical applications, including but not limited to diagnostics, therapeutics, biosensing, bioimaging, drug and gene delivery, tissue engineering and regenerative medicine. A state-of-the-art literature review of composite tissue scaffolds fabricated using these nanomaterials is provided, including the unique physicochemical properties and mechanisms that induce cell adhesion, growth, and differentiation into specific tissues. In addition, in vitro and in vivo cytotoxic effects and biodegradation behavior of these nanomaterials are presented. We also discuss challenges and gaps that still exist and need to be addressed in future research before clinical translation of these promising nanomaterials can be realized in a safe, efficacious, and economical manner.

Large‐Scale Formation of Uniform Porous Ge Nanostructures with Tunable Physical Properties

AbstractPorous germanium (PGe) nanostructures attract a lot of attention for various emerging applications due to their unique properties. Consequently, there is an increasing need for the development of low‐cost synthesis routes that are compatible with large‐scale production. Bipolar electrochemical etching (BEE) is a widely used solution for producing porous Ge layers. However, the lack of controllable production of large‐scale uniform PGe layers is the limiting factor for mainstream applications. Large‐scale homogeneous PGe layers formation is demonstrated by improving the BEE process. The PGe structures demonstrate excellent homogeneity in thickness and porosity, with a relative variation of below 2% across the 100 mm wafer. Furthermore, this process enables accurate tuning of the PGe's physical properties through variation of the etching parameters. PGe structures with porosity ranging from 40% to 80% and an adjustable thickness, while preserving low surface roughness are demonstrated, giving access to a large variety of PGe nanostructures for a wide range of applications. Ellipsometry and X‐ray reflectivity are employed to measure the porosity and thickness of PGe layers, providing fast and non‐destructive methods of characterization. These findings lay the groundwork for the large‐scale production of high‐quality PGe layers with on‐demand characteristics.

Competing excitation paths in luminescent heterobimetallic Ln-Al complexes: Unraveling interactions via experimental and theoretical investigations

The interest for heterometallic lanthanide-d or-p metal (Ln-M) complexes is growing because of a potential cooperative or synergistic effect related to the proximity of two different metals in the same molecular architecture affording special tunable physical properties. To exploit the potentiality of Ln-M complexes, suitable synthetic approaches, and the in-depth understanding of the effect of each building block on their properties are mandatory. Here, we report the study on a family of heterometallic luminescent complexes [Ln(hfac)3Al(L)3], Ln= Eu3+ and Tb3+. Using different L ligands, we investigated the effect of the steric and electronic properties of the Al(L)3 fragment, highlighting the general validity of the employed synthetic route. Amarked difference in the light emission of [Eu(hfac)3Al(L)3] and [Tb(hfac)3Al(L)3] complexes has been observed. Thanks to photoluminescence experiments and Density Functional Theory calculations, Ln3+ emissions are explained with a model involving two non-interacting excitation paths through hfac or Al(L)3 ligands.

Closed‐loop recycling of additive manufacturing waste for value‐added automotive foam applications

AbstractPolyurethane (PU) foams are used in various automotive applications due to their low cost and weight and highly tunable mechanical and physical properties. This article explores the effect of adding recycled thermoplastic elastomer (TPE) and recycled thermoplastic polyurethane (TPU) powder collected from 3D printing waste as filler material on thermal stability and mechanical, physical, and sound absorption properties of flexible PU foam. The incorporation of TPE powder at low filler content, 2.5 wt%, increased the compression modulus by over 140%, tear resistance by over 25%, and Young's Modulus by 50% compared to the control. The addition of 2.5 wt% TPU powder increased the compression modulus by 61%, tear resistance by 31%, and Young's Modulus by 84%. The addition of TPU powder at 2.5 wt% showed improvement in sound absorption of plane waves (up to 20% at 2500 Hz) for a frequency range of 50–3500 Hz. Adding an additive manufacturing waste stream into PU foam as a filler reduced waste to landfill and created a superior foam product. This article exemplifies the benefits of creating a closed‐loop plastic industry to improve polymer materials and protect the earth.

Correlation between Physical Properties of 12-Hydroxystearic Acid Organogels and Hansen Solubility Parameters.

The Hansen solubility parameter (HSP) is a useful index for reasoning the gelation behavior of low-molecular-weight gelators (LMWGs). However, the conventional HSP-based methods only "classify" solvents that can and cannot form gels and require many trials to achieve this. For engineering purposes, quantitative estimation of gel properties using the HSP is highly desired. In this study, we measured critical gelation concentrations based on three distinct definitions, mechanical strength, and light transmittance of organogels prepared with 12-hydroxystearic acid (12HSA) and correlated them with the HSP of solvents. The results demonstrated that the mechanical strength, in particular, strongly correlated with the distance of 12HSA and solvent in the HSP space. Additionally, the results indicated that the constant volume-based concentration should be used when comparing the properties of organogels to a different solvent. These findings are helpful in efficiently determining the gelation sphere of new LMWGs in HSP space and contribute to designing organogels with tunable physical properties.

Structuring supramolecular hyaluronan hydrogels via peptide self-assembly for modulating the cell microenvironment.

The use of synthetic extracellular matrices (ECMs) in fundamental in vitro cell culture studies has been instrumental for investigating the interplay between cells and matrix components. To provide cells with a more native environment in vitro, it is desirable to design matrices that are biomimetic and emulate compositional and structural features of natural ECMs. Here, the supramolecular fabrication of peptide-hyaluronan (HA) hydrogels is presented as potential ECM surrogates, combining native HA and rationally designed cationic amphipatic peptides [(KI)nK, lysine (K), isoleucine (I), n​=​2-6] whose mechanical properties and microstructure are tunable by the peptide sequence. (KI)nK peptides adopt β-sheet configuration and self-assemble into filamentous nanostructures triggered by pH or ionic strength. The self-assembly propensity of (KI)nK peptides increases with the sequence length, forming single phase hydrogels (shorter peptides) or with phase separation (longer peptides) in presence of the anionic polyelectrolyte HA through electrostatic complexations. The gel phase formed in (KI)nK-HA complexes exhibits viscoelastic behavior and triggers the formation of human mesenchymal stem cell (MSC) spheroids which disassemble over the time. It is anticipated that these (KI)nK-HA hydrogels with tunable physical and biochemical properties offer a promising platform for in vitro applications and in stem cell therapy.

Marble waste reinforced composite with tunable physico-mechanical and thermal properties: micromechanical simulation assisted experimental investigation

ABSTRACT This paper investigates the development of waste marble dust-reinforced particulate composites through an integrated approach of investigation. Samples of marble-epoxy composites were prepared with systematic variations in filler content to achieve tunable mechanical, physical, and thermal properties. Increasing ceramic filler's loading level resulted in superior properties of composite samples, as demonstrated by macroscale characterization such as compressive and flexural strength. Microstructural characterizations such as Fourier transform infrared spectroscopy (FT-IR), Field emission scanning electron microscopy (FE-SEM), thermogravimetric analysis (TGA), and X-ray diffraction (XRD) analysis were used to better understand the results. FT-IR results indicate chemical linkages forming between the epoxy resin and marble dust in the composite, while FE-SEM images suggest strong interfacial bonding between filler and matrix. TGA analysis shows enhancement of thermal properties with increasing filler content, while XRD indicates enhancement of crystallinity. Micro-mechanical modeling using the representative volume element (RVE) approach was also carried out using a commercial simulation package, determining Young’s modulus and comparing it with experimental results.

Emerging 2D Metal Oxides: From Synthesis to Device Integration.

2D metal oxides have aroused increasing attention in the field of electronics and optoelectronics due to their intriguing physical properties. In this review, an overview of recent advances on synthesis of 2D metal oxides and their electronic applications is presented. First, the tunable physical properties of 2D metal oxides that relate to the structure (various oxidation-state forms, polymorphism, etc.), crystallinity and defects (anisotropy, point defects, and grain boundary), and thickness (quantum confinement effect, interfacial effect, etc.) are discussed. Then, advanced synthesis methods for 2D metal oxides besides mechanical exfoliation are introduced and classified into solution process, vapor-phase deposition, and native oxidation on a metal source. Later, the various roles of 2D metal oxides in widespread applications, i.e., transistors, inverters, photodetectors, piezotronics, memristors, and potential applications (solar cell, spintronics, and superconducting devices) are discussed. Finally, an outlook of existing challenges and future opportunities in 2D metal oxides is proposed.

Evaluating the in vivo stability of water-soluble PEG-PLA copolymers using FRET imaging

Biodegradable and biocompatible polymer materials with tunable physical properties present a great interest for controlled drug delivery applications. A good example is BEPO®, a clinical-stage in situ-forming depot technology based on the utilization of a blend of poly(ethylene glycol)-b-poly(D,L-lactic acid) (PEG-PLA) diblock and triblock amphiphilic copolymers dissolved in an organic solvent. Once injected, this technology will form a bioresorbable solid polymer depot that will allow the release of a drug from weeks to months. The safety of the final degradation products from this technology, i.e., PEG and lactic acid, is well-documented. However, little information exists about the fate of intermediate degradants, specifically of water-soluble PEG-PLA chains where the molecular weights of the PLA block are short. Herein, we designed a Förster Resonance Energy Transfer (FRET) system for short copolymers, suitable for longitudinal in vivo imaging in the subcutaneous space, allowing to follow the stability of these products. Our results confirm that these species, that might be leaked from BEPO® depots during degradation, are rapidly hydrolyzed in the subcutaneous space of mice, forming approved products by Health Authorities, i.e., PEG and PLA homopolymers and/or lactic acid.

Non‐van der Waals 2D Materials for Electrochemical Energy Storage

AbstractThe development of advanced electrode materials for the next generation of electrochemical energy storage (EES) solutions has attracted profound research attention as a key enabling technology toward decarbonization and electrification of transportation. Since the discovery of graphene's remarkable properties, 2D nanomaterials, derivatives, and heterostructures thereof, have emerged as some of the most promising electrode components in batteries and supercapacitors owing to their unique and tunable physical, chemical, and electronic properties, commonly not observed in their 3D counterparts. This review particularly focuses on recent advances in EES technologies related to 2D crystals originating from non‐layered 3D solids (non‐van der Waals; nvdW) and their hallmark features pertaining to this field of application. Emphasis is given to the methods and challenges in top‐down and bottom‐up strategies toward nvdW 2D sheets and their influence on the materials’ features, such as charge transport properties, functionalization, or adsorption dynamics. The exciting advances in nvdW 2D‐based electrode materials of different compositions and mechanisms of operation in EES are discussed. Finally, the opportunities and challenges of nvdW 2D systems are highlighted not only in electrochemical energy storage but also in other applications, including spintronics, magnetism, and catalysis.

First-principles calculations integrated with experimental optical and electronic properties for MoS2-graphene heterostructures and MoS2-graphene-Au heterointerfaces

We present a computational and experimental study for various heterostructures and heterointerfaces comprising two-dimensional (2D) molybdenum disulfide (MoS2) and graphene (Gr) supported on gold (Au). These structures are useful for photo-electrochemical and nanophotonic applications, as well as for hydrogen generation. The frequency-dependent dielectric function, the refractive index, and the reflectivity are calculated using light polarization parallel and perpendicular to the respective monolayer c axis. We identify the transitions within MoS2 and graphene, which correspond to peaks in the imaginary part of the frequency-dependent dielectric function. The Gr-MoS2 dielectric function appears as a composition of the corresponding dielectric functions from the isolated monolayers with their peaks being shifted. However, for the Gr-MoS2-Au heterointerfaces, some of these peaks from the isolated monolayers are no longer detected. Charge transfers and work function calculations show that MoS2 and graphene are n and p-type semiconductors, respectively, which agree with our experimental local photoconductivity measurements. The heterojunction behavior for Gr-MoS2 is attributed to the interlayer electronic coupling, while minimizing Fermi level pinning at the MoS2/Au interface and charge transfers from graphene to MoS2. Thus, interfacing MoS2 with graphene signifies substrate engineering, allowing tunable MoS2 physical properties for diverse applications across the electromagnetic spectrum.

Chitin-Glucan Complex Hydrogels: Physical-Chemical Characterization, Stability, In Vitro Drug Permeation, and Biological Assessment in Primary Cells

Chitin-glucan complex (CGC) hydrogels were fabricated by coagulation of the biopolymer from an aqueous alkaline solution, and their morphology, swelling behavior, mechanical, rheological, and biological properties were studied. In addition, their in vitro drug loading/release ability and permeation through mimic-skin artificial membranes (Strat-M) were assessed. The CGC hydrogels prepared from 4 and 6 wt% CGC suspensions (Na51*4 and Na51*6 hydrogels, respectively) had polymer contents of 2.40 ± 0.15 and 3.09 ± 0.22 wt%, respectively, and displayed a highly porous microstructure, characterized by compressive moduli of 39.36 and 47.30 kPa and storage moduli of 523.20 and 7012.25 Pa, respectively. Both hydrogels had a spontaneous and almost immediate swelling in aqueous media, and a high-water retention capacity (>80%), after 30 min incubation at 37 °C. Nevertheless, the Na51*4 hydrogels had higher fatigue resistance and slightly higher-water retention capacity. These hydrogels were loaded with caffeine, ibuprofen, diclofenac, or salicylic acid, reaching entrapment efficiency values ranging between 13.11 ± 0.49% for caffeine, and 15.15 ± 1.54% for salicylic acid. Similar release profiles in PBS were observed for all tested APIs, comprising an initial fast release followed by a steady slower release. In vitro permeation experiments through Strat-M membranes using Franz diffusion cells showed considerably higher permeation fluxes for caffeine (33.09 µg/cm2/h) and salicylic acid (19.53 µg/cm2/h), compared to ibuprofen sodium and diclofenac sodium (4.26 and 0.44 µg/cm2/h, respectively). Analysis in normal human dermal fibroblasts revealed that CGC hydrogels have no major effects on the viability, migration ability, and morphology of the cells. Given their demonstrated features, CGC hydrogels are very promising structures, displaying tunable physical properties, which support their future development into novel transdermal drug delivery platforms.

Enzymatically-Crosslinked Gelatin Hydrogels with Nanostructured Architecture and Self-Healing Performance for Potential Use as Wound Dressings.

Development of natural protein-based hydrogels with self-healing performance and tunable physical properties has attracted increased attention owing to their wide potential not only in the pharmaceutical field, but also in wounds management. This work reports the development of a versatile hydrogel based on enzymatically-crosslinked gelatin and nanogels loaded with amoxicillin (Amox), an antibiotic used in wound infections. The transglutaminase (TGase)-crosslinked hydrogels and encapsulating nanogels were formed rapidly through enzymatic crosslinking and self-assembly interactions in mild conditions. The nanogels formed through the self-assemble of maleoyl-chitosan (MAC5) and polyaspartic acid (PAS) may have positive influence on the self-healing capacity and drug distribution within the hydrogel network through the interactions established between gelatin and gel-like nanocarriers. The physicochemical properties of the enzymatically-crosslinked hydrogels, such as internal structure, swelling and degradation behavior, were studied. In addition, the Amox release studies indicated a rapid release when the pH of the medium decreased, which represents a favorable characteristic for use in the healing of infected wounds. It was further observed through the in vitro and in vivo biocompatibility assays that the optimized scaffolds have great potential to be used as wound dressings.

Recent Progress of Conductive Hydrogel Fibers for Flexible Electronics: Fabrications, Applications, and Perspectives

AbstractFlexible conductive materials with intrinsic structural characteristics are currently in the spotlight of both fundamental science and advanced technological applications due to their functional preponderances such as the remarkable conductivity, excellent mechanical properties, and tunable physical and chemical properties, and so on. Typically, conductive hydrogel fibers (CHFs) are promising candidates owing to their unique characteristics including light weight, high length‐to‐diameter ratio, high deformability, and so on. Herein, a comprehensive overview of the cutting‐edge advances the CHFs involving the architectural features, function characteristics, fabrication strategies, applications, and perspectives in flexible electronics are provided. The fundamental design principles and fabrication strategies are systematically introduced including the discontinuous fabrication (the capillary polymerization and the draw spinning) and the continuous fabrication (the wet spinning, the microfluidic spinning, 3D printing, and the electrospinning). In addition, their potential applications are crucially emphasized such as flexible energy harvesting devices, flexible energy storage devices, flexible smart sensors, and flexible biomedical electronics. This review concludes with a perspective on the challenges and opportunities of such attractive CHFs, allowing for better understanding of the fundamentals and the development of advanced conductive hydrogel materials.

How to Tailor Porous Boron Nitride Properties for Applications in Interfacial Processes.

The research of new porous materials for applications in interfacial processes is key to addressing global energy and sustainability challenges. For example, porous materials can be used to store fuels such as hydrogen or methane or to separate chemical mixtures reducing the energy currently required by thermal separation processes. Their catalytic properties can be exploited to convert adsorbed molecules into valuable or less hazardous chemicals, thereby reducing energy consumption or pollutants emissions. Porous boron nitride (BN) has appeared as a promising material for applications in molecular separations, gas storage, and catalysis owing to its high surface area and thermal stability, as well as its tunable physical properties and chemistry. However, the production of porous BN is still limited to the laboratory scale, and its formation mechanism, as well as ways to control porosity and chemistry, are yet to be fully understood. In addition, studies have pointed toward the instability of porous BN materials when exposed to humidity, which could significantly impact performance in industrial applications. Studies on porous BN performance and recyclability when employed in adsorption, gas storage, and catalysis remain limited, despite encouraging preliminary studies. Moreover, porous BN powder must be shaped into macrostructures (e.g., pellets) to be used commercially. However, common methods to shape porous materials into macrostructures often cause a reduction in the surface area and/or mechanical strength. In recent years, research groups, including ours, have started addressing the challenges discussed above. Herein, we summarize our collective findings through a selection of key studies. First, we discuss the chemistry and structure of BN, clarifying confusion around terminology and discussing the hydrolytic instability of the material in relation to its structure and chemistry. We demonstrate a way to reduce the instability in water while still maintaining high specific surface area. We propose a mechanism for the formation of porous BN and discuss the effects of different synthesis parameters on the structure and chemistry of porous BN, therefore providing a way to tune its properties for selected applications. While the syntheses covered often lead to a powder product, we also present ways to shape porous BN powders into macrostructures while still maintaining high accessible surface area for interfacial processes. Finally, we evaluate porous BN performance for chemical separations, gas storage, and catalysis. While the above highlights key advances in the field, further work is needed to allow deployment of porous BN. Specifically, we suggest evaluating its hydrolytic stability, refining the ways to shape the material into stable and reproducible macrostructures, establishing clear design rules to produce BN with specific chemistry and porosity, and, finally, providing standardized test procedures to evaluate porous BN catalytic and sorptive properties to facilitate comparison.

Air-based sputtering deposition of titanium oxynitride-based single, gradient, and multi-layer thin films for photoelectrochemical applications

Titanium oxynitride (TiNxOy) thin films exhibiting tunable physical and chemical properties can be used in many fields. Air-based sputtering deposition of the films with diverse O/N ratios was employed to produce gradient and multilayer films. By solely altering the air/Ar flow ratio, obtained TiNxOy films could change from a crystalline to a mainly amorphous feature. Moreover, the carrier concentration, Hall mobility, and hence resistivity of the films could be modified to a large range. The optical bandgaps of the films could also be tailored to a wide extent. Based on these results, the gradient TiNxOy layer and TiNxOy/TiN(O) multilayer were also deposited on TiN(O)-coated glass substrates for the assessment of photoelectrochemical performance. Compared with the TiNxOy/TiN(O) bilayer with the best photoelectrochemical performance, the photoelectrochemical currents of gradient TiNxOy films could be improved from 99 ± 2 μA⋅cm−2 to 164 ± 2 μA⋅cm−2 by taking advantage of bandgap engineering. Additionally, the photoelectrochemical currents of TiNxOy/TiN(O) multilayer were further improved to 175 ± 6 μA⋅cm−2. This is mainly due to conductive nano TiN(O) layers providing multiple high-transport paths while allowing light transmission. The enhancement mechanisms of the gradient and multilayer films have also been elaborated.

Tunable Interlayer Interactions in Reduced Graphene Oxide Paper.

Free-standing graphene-based paper-like materials have garnered significant interest for various applications because of their tunable physical and chemical properties, along with unique multilayered structures. Because of the layered configuration of graphene paper, characterization of the interactions between graphene sheets is critical for understanding its fundamental properties and applications. We investigate the interlayer cohesion energies in graphene papers using the mode I fracture concept with double cantilever beam specimens. Mechanical separation along the middle of the graphene paper thickness enables the evaluation of interlayer bonding strength in the paper. Starting from graphene oxide paper, the chemical reduction using hydroiodic acid tunes the interlayer cohesion energy from 11.30 ± 0.25 to 4.78 ± 0.18 J/m2 as the reduction time increases. The interlayer cohesion energy is correlated with the oxygen content, interlayer spacing, and electrical conductivity of graphene papers. This work provides a fundamental characterization of the interlayer cohesion energy of graphene paper and establishes the potential for tunability of the interlayer interactions in graphene paper.

Co0.75Mo3S3.75/CoS2@2D-MoS2 nanosheets on carbon cloth: A progressive binder-free electrocatalyst for hydrogen evolution reaction

The development of ultrathin non-noble metal dichalcogenide electrocatalysts with tunable physical properties such as phase transformations, defect engineering, and activating plane edges is essential in order to enhance their electrocatalytic performance for water splitting applications. In this present work, we account to report a facile approach to cationic modulations through a single-step hydrothermal approach for the fabrication of a two-dimensional (2D) self-assembled ultrathin Co0.75Mo3S3.75/CoS2 (Co–Mo–S) @MoS2 nanoflowers directly grown on carbon fibre cloth. The systematic physicochemical relationship of cobalt ion modulations into MoS2 nanoflowers (Co/Mo/S) enabled the formation of flower-like Co–Mo–S@MoS2 ultrathin nanosheets with enhanced active sites, resulting in enhanced electrocatalytic contribution for hydrogen evolution reaction. The synthesised catalyst exhibited an ultralow overpotential value of 43 mV (RHE) at 20 mA/cm2, very small Tafel value of ∼36.6 mV/dec, and long durability/stability of 51 h of electrolysis. As a whole, these presented results demonstrate a rational construction of 2D ion modulated MoS2 ultrathin nanosheet electrodes that are beneficial for sustainable energy storage devices, which could be potentially extended to other dimensional MoS2 based materials.

Bi2S3Electron Transport Layer Incorporation for High-Performance Heterostructure HgTe Colloidal Quantum Dot Infrared Photodetectors

Infrared photodetectors (PDs) based on epitaxial semiconductors occupy the majority of the market, but their high cost from material growth and device integration limits their application fields. Colloidal quantum dots (CQDs) provide a high potential candidate for infrared PDs due to their unique infrared sensitivity, tunable physical and chemical properties, and good compatibility with readout integration circuits. In particular, HgTe CQD PDs have demonstrated a wide detection range from short-wave to long-wave infrared. Although significant progress has been achieved in HgTe CQD infrared PDs, they are still in the primary stage of QD synthesis and prototype device fabrication. Here, we develop a new p–i–n photodiode from the traditional p–i device structure. Bismuth sulfide (Bi2S3) films were adopted as the electron transport layer, which could favor uniform absorber deposition, superior charge extraction, and suppressed interfacial loss. The Bi2S3-based photodiodes have achieved a room-temperature dark current density as low as 1.6 × 10–5 A/cm2 at −400 mV. Furthermore, their specific detectivity (D*) achieves ∼1011 Jones at room temperature.