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Thermoelectric (TE) devices provide a clean and environmentally friendly technique for energy conversion. There is, however, limited published research addressing the optimal design and fabrication of flexible thermoelectric generators (TEGs), which use nanostructured materials and can conform to the contours of the geometry on which they are mounted. This paper describes a novel technological route that was found to be a promising approach for realising nanostructured energy harvesters on flexible substrates operating at small temperature gradients < 20 K and suitable for wearable applications. By comparison, current commercial rigid TEGs operate at temperature gradients of 50–70 K. The fabrication process reported here requires a combination of traditional silicon microfabrication techniques, electroplating and ion-track nanolithography. Polyimide nanotemplates, with pore diameters ranging from 30 to 120 nm and a high aspect ratio (1:1000), were fabricated from Kapton foil with a thickness of 20 µm. Bi2Te3 and Bi0.5Sb1.5Te3 nanowires (80–120 nm) were successfully electrodeposited into such templates. Both compounds had optimal microstructural properties for thermoelectric applications. While Bi2Te3 (n-type element) films had a close-to-stoichiometric composition (Bi2.17Te2.81), Bi0.5Sb1.5Te3 (p-type element) samples exhibited significant deviations from their stoichiometric composition from Bi0.37Sb1. 44Te3.20 to Bi0.29Sb1. 43Te3.27. [ABSTRACT FROM AUTHOR]

The size, size distribution and shape of ferroelectric BaTiO3 nanoparticles were determined using three different imaging techniques. The nanoparticles fabricated by milling microcrystals were found to have sizes of 12 ± 3 nm, 15 ± 3 nm and 18 ± 3 nm. Liquid crystal suspensions with 1% concentration of nanoparticles were prepared and their dielectric and optical anisotropy were measured. It is shown that the largest particles lead to the strongest enhancement of dielectric and optical anisotropy, as compared with undoped liquid crystals. [ABSTRACT FROM AUTHOR]

A CdTe-based optical metamaterial, with large induced optical birefringence (4%), has been produced and its optical properties fully characterized and modeled over the spectral range 1500– 450 nm. This metamaterial, which is related to mesoporous silica, is made using electrochemical deposition in the presence of a lyotropic liquid crystal template. This process produces a stoichiometric CdTe film containing a hexagonal array of ∼4.2 nm cylindrical pores with interpore separation ∼6.5 nm. A model of the dielectric properties of the films indicates that their birefringence can be entirely attributed to the film’s nanoporosity. [ABSTRACT FROM AUTHOR]

The pursuit of high-performance thermoelectric materials is of paramount importance in addressing energy sustainability and environmental concerns. Here, we explore the multifaceted impact of sulfur passivation in the matrix of tellurium nanowires (TeNWs), encompassing environmental control, thermoelectric properties, and charge carrier mobility. In this study, we present the facile production of TeNWs using an aqueous solution synthesis approach. The synthesized TeNWs were subsequently subjected to surface modification involving sulfur moieties. Our findings demonstrate that sulfur passivation not only effectively safeguards the nanowires from environmental degradation but also significantly augments their thermoelectric properties. Notably, the highest recorded values were achieved at 560 K for passivated tellurium nanowires, exhibiting a Seebeck coefficient of 246 μV/K, an electrical conductivity of 14.2 S/cm, and power factors of 86.7 μW/m-K 2 . This strategy presents a promising avenue for the development of advanced thermoelectric materials for applications in energy harvesting, waste heat recovery, and sustainable energy conversion technologies.

Organic-inorganic hybrid thermoelectric (TE) materials have attracted tremendous interest for harvesting waste heat energy. Due to their mechanical flexibility, inorganic-organic hybrid TE materials are considered to be promising candidates for flexible energy harvesting devices. In this work, enhanced TE properties of Tellurium (Te) nanowires (NWs)- poly (3-hexylthiophene-2, 5-diyl) (P3HT) hybrid materials are reported by improving the charge transport at interfacial layer mediated via controlled oxidation. A power factor of ≈9.8 µW (mK 2 ) -1 is obtained at room temperature for oxidized P3HT-TeNWs hybrid materials, which increases to ≈64.8 µW (mK 2 ) -1 upon control of TeNWs oxidation. This value is sevenfold higher compared to P3HT-TeNWs-based hybrid materials reported in the literature. MD simulation reveals that oxidation-free TeNWs demonstrate better templating for P3HT polymer compared to oxidized TeNWs. The Kang-Snyder model is used to study the charge transport in these hybrid materials. A large σ E0 value is obtained which is related to better templating of P3HT on oxygen-free TeNWs. This work provides evidence that oxidation control of TeNWs is critical for better interface-driven charge transport, which enhances the thermoelectric properties of TeNWs-P3HT hybrid materials. This work provides a new avenue to improve the thermoelectric properties of a new class of hybrid thermoelectric materials., (© 2024 The Author(s). Advanced Science published by Wiley‐VCH GmbH.)

We report the first result of a study in which molecular iodine has been incorporated via incipient wetness impregnation into the two-dimensional semiconducting metal-organic framework (MOF) Cu 3 (2,3,6,7,10,11-hexahydroxytriphenylene) 2 Cu 3 (HHTP) 2 to enhance its thermoelectric properties. A power factor of 0.757 μW m -1 K -2 for this MOF was obtained which demonstrates that this provides an effective route for the preparation of moderate-performance thermoelectric MOFs.

In this work we demonstrate a new approach towards the electroless deposition of tellurium nanowires in deep eutectic solvents. Unlike most electroless deposition where the substrate is sacrificed to drive the reduction, our process uses immobilised silver epoxy islands on gold films to give localised galvanic displacement of the silver, resulting in an even growth of wires across the entire gold electrode surface. We demonstrate the strong dependence of the nanostructure on the experimental conditions, with changes in bath temperature, tellurium concentration and the halide component of the solvent leading to sizeable alterations in the nanowire geometry. This demonstrates electroless deposition as a promising synthetic route towards low-dimensional tellurium nanostructures., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

In this work, a switch from n-type to p-type conductivity in electrodeposited Cu 3 (2,3,6,7,10,11-hexahydroxytriphenylene) 2 [Cu 3 (HHTP 2 )] has been observed, which is most likely due to oxygen molecular doping. The synthesis of electrically conductive 2D metal-organic frameworks (MOFs) has been achieved through the introduction of highly conjugated organic linkers coordinated to their constituent metal-ion centers. However, the porous structure and unsaturated metal sites in MOFs make them susceptible to ambient adsorbates, which can affect their charge transport properties. This phenomenon has been experimentally investigated by GIXRD, Hall effect and Seebeck measurements, and X-ray photoelectron spectroscopy.

The discovery of novel materials for thermoelectric energy conversion has potential to be accelerated by data-driven screening combined with high-throughput calculations. One way to increase the efficacy of successfully choosing a candidate material is through its evaluation using transport descriptors. Using a data-driven screening, we selected 12 potential candidates in the trigonal ABX 2 family, followed by charge transport property simulations from first principles. The results suggest that carrier scattering processes in these materials are dominated by ionised impurities and polar optical phonons, contrary to the oft-assumed acoustic-phonon-dominated scattering. Using these data, we further derive ground-state transport descriptors for the carrier mobility and the thermoelectric powerfactor. In addition to low carrier mass, high dielectric constant was found to be an important factor towards high carrier mobility. A quadratic correlation between dielectric constant and transport performance was established and further validated with literature. Looking ahead, dielectric constant can potentially be exploited as an independent criterion towards improved thermoelectric performance. Combined with calculations of thermal conductivity including Peierls and inter-branch coherent contributions, we conclude that the trigonal ABX 2 family has potential as high performance thermoelectrics in the intermediate temperature range for low grade waste heat harvesting.

The best known thermoelectric material for near room temperature heat-to-electricity conversion is bismuth telluride. Amongst the possible fabrication techniques, electrodeposition has attracted attention due to its simplicity and low cost. However, the measurement of the thermoelectric properties of electrodeposited films is challenging because of the conducting seed layer underneath the film. Here, we develop a method to directly measure the thermoelectric properties of electrodeposited bismuth telluride thin films, grown on indium tin oxide. Using this technique, the temperature dependent thermoelectric properties (Seebeck coefficient and electrical conductivity) of electrodeposited thin films have been measured down to 100 K. A parallel resistor model is employed to discern the signal of the film from the signal of the seed layer and the data are carefully analysed and contextualized with literature. Our analysis demonstrates that the thermoelectric properties of electrodeposited films can be accurately evaluated without inflicting any damage to the films.

Direct patterning of thermoelectric metal chalcogenides can be challenging and is normally constrained to certain geometries and sizes. Here we report the synthesis, characterization, and direct writing of sub-10 nm wide bismuth sulfide (Bi 2 S 3 ) using a single-source, spin-coatable, and electron-beam-sensitive bismuth(III) ethylxanthate precursor. In order to increase the intrinsically low carrier concentration of pristine Bi 2 S 3 , we developed a self-doping methodology in which sulfur vacancies are manipulated by tuning the temperature during vacuum annealing, to produce an electron-rich thermoelectric material. We report a room-temperature electrical conductivity of 6 S m -1 and a Seebeck coefficient of -21.41 μV K -1 for a directly patterned, substoichiometric Bi 2 S 3 thin film. We expect that our demonstration of directly writable thermoelectric films, with further optimization of structure and morphology, can be useful for on-chip applications.

Tin selenide (SnSe) has attracted much attention in the thermoelectric community since the discovery of the record figure of merit (ZT) of 2.6 in single crystal tin selenide in 2014. There have been many reports since of the thermoelectric characterization of SnSe synthesized or manufactured by several methods, but so far none of these have concerned the electrodeposition of SnSe. In this work, stoichiometric SnSe was successfully electrodeposited at -0.50 V vs SCE as shown by EDX, XPS, UPS, and XRD. The full ZT of the electrodeposits were then measured. This was done by both a delamination technique to measure the Seebeck coefficient and electrical conductivity which showed a peak power factor of 4.2 and 5.8 μW m -1 K -2 for the as deposited and heat-treated films, respectively. A novel modified transient 3ω method was used to measure the thermal conductivity of the deposited films on the deposition substrate. This revealed the thermal conductivity to be similar to the ultralow thermal conductivity of single crystal SnSe, with a value of 0.34 W m -1 K -1 being observed at 313 K.

Aggregation is a pathological hallmark of proteinopathies such as Alzheimer's disease and results in the deposition of β-sheet-rich amyloidogenic protein aggregates. Such proteinopathies can be classified by the identity of one or more aggregated proteins, with recent evidence also suggesting that distinct molecular conformers (strains) of the same protein can be observed in different diseases, as well is in subtypes of the same disease. Therefore, methods for the quantification of pathological changes in protein conformation are central to understanding and treating proteinopathies. In this work, the evolution of Raman spectroscopic molecular signatures of three conformationally distinct proteins, bovine serum albumin (α-helical-rich), β2-microglobulin (β-sheet-rich), and tau (natively disordered), was assessed during aggregation into oligomers and fibrils. The morphological evolution was tracked using atomic force microscopy and corresponding conformational changes were assessed by their Raman signatures acquired in both wet and dried conditions. A deconvolution model was developed which allowed us to quantify the conformation of the nonregular protein tau, as well as for the oligomeric and fibrillar species of each of the proteins. Principle component analysis of the fingerprint region allowed further identification of the distinguishing spectral features and unsupervised distinction. While an increase in β-sheet is seen on aggregation, crucially, however, each protein also retains a significant proportion of its native monomeric structure after aggregation. Thus, spectral analysis of each aggregated species, oligomeric, as well as fibrillar, for each protein resulted in a unique and quantitative "conformational fingerprint". This approach allowed us to provide the first differential detection of both oligomers and fibrils of the three different amyloidogenic proteins, including tau, whose aggregates have never before been interrogated using spontaneous Raman spectroscopy. Quantitative "conformational fingerprinting" by Raman spectroscopy thus demonstrates its huge potential and utility in understanding proteinopathic disease mechanisms and for providing strain-specific early diagnostic markers and targets for disease-modifying therapies.

DNA-mediated self-assembly of nanoparticles has been of great interest because it enables access to nanoparticle superstructures that cannot be synthesized otherwise. However, the programmability of higher order nanoparticle structures can be easily lost under DNA denaturing conditions. Here, we demonstrate that light can be employed as an external stimulus to master the stability of nanoparticle superlattices (SLs) via the promotion of a reversible photoligation of DNA in SLs. The oligonucleotides attached to the nanoparticles are encoded to ligate using 365 nm light, effectively locking the SLs and rendering them stable under DNA denaturing conditions. The reversible process of unlocking these structures is possible by irradiation with light at 315 nm, recovering the structures to their natural state. Our work inspires an alternative research direction toward postassembly manipulation of nanoparticle superstructures using external stimuli as a tool to enrich the library of additional material forms and their application in different media and environments.

We report a simple, single-cycle synthetic method for forming highly-crystalline, micron-sized monolayer domains of phase-pure MoS 2 . This method combines liquid chemistry with discrete, layer-by-layer deposition from a novel Mo precursor. Single-crystalline MoS 2 with domain sizes up to 100 μm have been obtained and characterised by optical and electron microscopy as well as Raman and photoluminescence spectroscopy.

Fuel cells are a key new green technology that have applications in both transport and portable power generation. Carbon-supported platinum (Pt) is used as an anode and cathode electrocatalyst in low-temperature fuel cells fueled with hydrogen or low-molecular-weight alcohols. The cost of Pt and the limited world supply are significant barriers to the widespread use of these types of fuel cells. Comparatively, palladium has a 3 times higher abundance in the Earth's crust. Here, a facile, low-temperature, and scalable synthetic route toward three-dimensional nanostructured palladium (Pd) employing electrochemical templating from inverse lyotropic lipid phases is presented. The obtained single diamond morphology Pd nanostructures exhibited excellent catalytic activity and stability toward methanol, ethanol, and glycerol oxidation compared to commercial Pd black, and the nanostructure was verified by small-angle X-ray scattering, scanning tunneling electron microscopy, and cyclic voltammetry.

ZnO nanotubes were prepared by selective dissolution of electrodeposited nanorods. The effect of solution pH, rod morphology, and chloride ion concentration on the dissolution mechanism was studied. The selective etching was rationalized in terms of the surface energy of the different ZnO crystal faces and reactant diffusion. The nanorod diameter and chloride concentration are the most influential parameters on the dissolution mechanism because they control homogeneous dissolution or selective etching of the (110) and (002) surfaces. Bulk solution pH only has an effect on the rate of dissolution. By accurate control of the dissolution process, the nanomorphology can be tailored, and the formation of rods with a thin diameter (10-20 nm), cavity, or ultra-thin-walled tubes (2-5 nm) can be achieved.

We have investigated the influence of the symmetry of the side chain substituents in high-mobility, solution processable n-type molecular semiconductors on the performance of organic field-effect transistors (OFETs). We compare two molecules with the same conjugated core, but either symmetric or asymmetric side chain substituents, and investigate the transport properties and thin film growth mode using scanning Kelvin probe microscopy (SKPM) and atomic force microscopy (AFM). We find that asymmetric side chains can induce a favorable two-dimensional growth mode with a bilayer structure, which enables ultrathin films with a single bilayer to exhibit excellent transport properties, while the symmetric molecules adopt an unfavorable three-dimensional growth mode in which transport in the first monolayer at the interface is severely hindered by high-resistance grain boundaries.

Thermodynamic instability is a problem when assembling and purifying complex DNA nanostructures formed by hybridization alone. To address this issue, we have used photochemical fixation and orthogonal copper-free, ring-strain-promoted, click chemistry for the synthesis of dimeric, trimeric, and oligomeric modular DNA scaffolds from cyclic, double-stranded, 80-mer DNA nanoconstructs. This particular combination of orthogonal click reactions was more effective for nanoassembly than others explored. The complex nanostructures are stable to heat and denaturation agents and can therefore be purified and characterized. They are addressable in a sequence-specific manner by triplex formation, and they can be reversibly and selectively deconstructed. Nanostructures utilizing this orthogonal, chemical fixation methodology can be used as building blocks for nanomachines and functional DNA nanoarchitectures.