We report cobalt oxide (Co3O4) and its composites with non-porous (NP) and porous (P) titanium dioxide (TiO2) as electrode materials for enhanced electrochemical performance and efficient charge transfer kinetics and oxygen evolution (OER)/hydrogen evolution (HER) reactions electrocatalysis. The surface area of the porous composite is 59.7 m2/g, and that of the non-porous (50.6 m2/g), as determined by Brunauer-Emmet-Teller analysis. Therefore, porous composite exhibits better electrochemical properties with an excellent specific capacitance (Cs) of 522 F/g at 0.5 A/g, and exhibits superior OER and HER with an overpotential of 493 mV at 150 mA/cm2, a low Tafel slope (42 mV/dec) and 366 mV at 50 mA/cm2 and a Tafel slope of 191 mV/dec, respectively. Real-time device testing, a hygrometer and 10 light-emitting diodes were powered on for 24 and 3 min, respectively. These results highlighted that the composite with TiO2(P) are a viable option for energy storage and water-splitting applications.

This study presents the design and synthesis of ternary SnO2/Co3O4/ZnO heterostructured nanofibers fabricated through electrospinning and wet-chemical techniques for high-performance asymmetric supercapacitors (ASCs). Structural analyses confirmed the successful formation of coupled oxide phases with uniform elemental dispersion in a porous fibrous network. The unique core–shell configuration and hierarchical architecture enabled efficient charge transport, high surface area, and abundant electroactive sites. Electrochemical evaluation revealed superior performance of the SnO2/Co3O4/ZnO electrode compared to binary counterparts, achieving a specific capacitance of 275 F/g at 1 A/g, an energy density of 36.6 Wh/kg, and excellent cycling stability with 89.6

We report crystalline cubic structured cobalt-based Prussian blue analogues (Co-PBAs), exhibiting excellent electrochemical and biomedical performance due to their electroactive redox centers. The Co-PBA exhibited excellent performance electrochemical performance in potassium hydroxide (KOH) electrolyte as compared to sodium hydroxide (NaOH) and lithium hydroxide (LiOH). The pseudocapacitive nature of Co-PBA was observed from cyclic voltammetry (CV) measurements in a three-electrode configuration, resulting a specific capacitance (Cp=378 F/g). Co-PBAs exhibited outstanding electrocatalytic performance, validated through oxygen evolution reaction (OER), achieving a overpotential of 335 mV at 30mA/cm2 and Tafel slope of 71 mV/dec. The Asymmetric device configuration shows a high specific capacitance (Cp) of 105 F/g at 1 A/g with an energy density of 70 Wh/kg, while the device maintains capacitive retention up to 92.35 % after 3000 charge discharge cycles. A coin cell setup was used to test the prototype, the LEDs and humidity sensors were run for 2 and 9 min respectively. As a good biomedical agent, Co-PBA exhibited excellent anti-bacterial activity against Escherichia coli (E. coli) having maximum inhibition zone of 20 mm at 40 & micro;g/mL. In vitro anti-inflammatory exhibited inhibition (85.5 %) of human red blood cell (HRBC) membrane lysis, compared to diclofenac sodium (88.3 %). They also demonstrated improved glucose uptake, ranging from 11.5 %-83.3 % at 10-80 & micro;g/mL concentrations, which is comparable to the standard drug (metronidazole). These results highlight the unique combination of electrochemical and biomedical demonstrating their potential applications in both supercapacitors and therapeutics.

This study presents the current-voltage (I-V) characteristics under dark conditions of the poly(3-hexylthiophene) (P3HT)-based diode fabricated by using electrospray-deposition (ESD). I-V curves under forward bias exhibited space-charge-limited current (SCLC) behavior. In the low-current region, the Shockley equation was applied while in the higher electric field region, the SCLC model was utilized to examine the various diode parameters related to the transport mechanism. The field-dependent hole mobility (µo) and electric field activation (γ) parameters were obtained from the I-V, resulting a 2.7 × 10⁻⁷ cm²/Vs (µo) and 3.45 × 10⁻⁴ (m/V)0.5 (γ), which aligns with values reported in the literature. Furthermore, the forward (FR) and reverse (RV) I-V scans revealed the evidence of deep localized states within the materials, resulting the impact of these trap states on carrier transport mechanism. These results demonstrate the deep insights and understanding of transport properties of the diode and highlighting its potential for use in organic semiconductor-based devices.

Natural organic/inorganic materials with rational cooperative formations have long been of enormous interest owing to their hybrid self-assembling properties. Natural biomolecules are expected to produce attractive superstructures capable of sensing their environment, following their inherent biological functions and high biocompatibility. However, understanding their assembly strategies with inorganic materials is often challenging. Herein, we investigated the bioactive assembly of natural eumelanin superstructures. modulated by chemical functionalization of micronized graphene oxide, to study their strong structural affinity by analysing their vibrational-structural correlations. The application of complementary experiments of high-resolution electron nanoimaging coupled with vibrational Raman spectroscopy revealed intriguing and unique features of this complex hybrid material. In particular, high-resolution nanodiffraction/imaging analysis provided evidence of new nanocrystalline domains of pure natural eumelanin with different and irregular orientations forming irregular nanosheets. Interestingly, a hierarchical reassembly process of eumelanin units are actually evident not only on the oxide graphene surface but also located in high amounts on the edge of vertical graphene oxide, concretely supported by the analytical changes of the predominant resonance bands (D, D**, and G). This confirmed the ability of eumelanin to reassemble in spherical and elongated nanostructures when induced by an external stimuli of graphene oxide in an aqueous solution at room temperature. Thus, this work highlights the assembling mechanisms for designing a strategy to control bioactive molecules through environment modification.

In the framework of the Circular Economy this study provides a detailed analysis of water-based suspensions of two biopolymers derived by sustainable processes: eumelanin from insect farming and keratin from chicken feathers. The latter material was obtained via two different extraction procedures. Colloidal-like suspensions were produced in water either as a single component system or a mixture of both in selected ratios, taking advantage of their high solubility. The suspensions were examined using a comprehensive set of chemical, structural and dielectric techniques to gather information on their properties. Small-Angle x-ray Scattering results provided insights into the elemental polymer sections within the suspension, while Transmission Electron Microscopy images indicate that keratin is the component driving the shape of the aggregation structure in a colloidal environment, and, in some cases, eumelanin internalization. Furthermore, the co-presence of both polymers in water determines the aggregation dimensions and shapes. The discussion focuses on the influence of the aggregation on the dielectric proper-ties by comparing the former to the AC dynamic response returned by Broadband Dielectric Spectroscopy (BDS). Within the BDS framework various items are highlighted including dielectric relaxations, screening effects, counterion condensation and ionic charge transport. The results shown in this work let to foresee the adoption of water or biofriendly aqueous BSF-EuM:Keratin suspensions in the production of devices and sensors with low environmental impact.

Hybrid systems between batteries and supercapacitors are designed to bridge the gap between both technologies, developing high-power, high-energy, and long cycle life energy storage devices. Moreover, in the urgent need to transition to a more sustainable energy model, sodium-based chemistries are an excellent alternative to lithiumbased technologies. While various approaches have been tried in Na-ion capacitor (NIC) cell design, the upsidedown NIC configuration remains underexplored. This consists of using a Na-containing battery-type cathode instead of an anode, which eliminates problems such as the need for pre-sodiation or Na-plating. This setup also allows the electrolyte concentration to stay stable, with ions exhibiting a rocking-chair motion, ensuring stable ionic conductivity during cycling. However, the potential window of these systems can be limited by the formation of the SEI on the capacitive negative electrode. Therefore, the aim of this paper is to explore the limitations of activated carbon (AC) in upside-down NICs through ex-situ X-ray photoemission spectroscopy (XPS) characterization and comprehensive monitoring of the electrode under various full-cell conditions, thereby assessing how far this configuration can be pushed in terms of energy. The proposed system features a high-rate capability cathode, a Na3V2O2(PO4)2F/C composite prepared via a novel one-step microwave synthesis, which delivers 64 mAh g- 1 at 50C. The negative electrode employs a dried olive pits-derived AC with a surface area of 2138 m2 g- 1. Together, they enable a full cell achieving up to 69 Wh kg- 1 at 19 W kg- 1 and 29 Wh kg-1 at 4915 W kg- 1, with an impressive capacity retention of 74 % after 10,000 charge-discharge cycles.

The modifications in the electronic properties induced by the thickness and size of an individual flake of transition-metal halides on different substrates (silicon oxide or In-doped tin oxide) are of particular technological interest, even more in the case of chromium trihalides (CrX3, X = Cl, Br, and I), whose longer lifetime under ambient conditions is particularly intriguing. By using synchrotron-based scanning photoelectron microscopy with a resolution of 0.1 μm and Kelvin probe force microscopy, we evaluated the surface modification reaction and the surface potential. Our results established the correlations of the two latter properties with the thickness of flakes, observing a natural tendency to preserve their characteristic when the flakes have significantly less thickness. This is in contrast to thicker flakes, which show alteration patterns similar to those observed in bulk-cleaved samples (Kazim, S.; Mastrippolito, D.; Moras, P.; Jugovac, M.; Klimczuk, T.; Ali, M.; Ottaviano, L.; Gunnella, R. Phys. Chem. Chem. Phys. 2023, 25, 3806-3814. https://doi.org/10.1039%2FD2CP04586A%29. This preliminary study investigates interfaces made by dry transfer of CrCl3 flakes in an atmospheric environment. Cl vacancies and the formation of O/CrCl3 are induced, serving as dissociation centers that facilitate the migration of Cl vacancies between the top and bottom surfaces. By manipulating 2D atomic layers via surface oxidation or the introduction of surface vacancies, a novel and versatile approach is unveiled for the development of low-dimensional multifunctional nanodevices.

Zinc-based Prussian blue analogues (Zn-PBAs) are emerging as versatile materials, showcasing remarkable potential in both energy storage and biomedical fields. Synthesized through co-precipitation, these materials exhibit a highly crystalline single-phase structure with polyhedron morphology that enhances their functionality. Electrochemical analysis reveals pseudo capacitive behavior with an impressive specific capacitance of 68 F/g, and excellent oxygen evolution reaction (OER) performance, achieving a low overpotential of 320 mV and a Tafel slope of 70 mV/dec in KOH electrolyte solution. A prototype device powered by Zn-PBAs ran a hygrometer and red LEDs. Additionally, Zn-PBAs exhibit significant biomedical properties, including antibacterial activity against Gram-negative pathogenic bacterial strains such as Escherichia coli (E. coli), and anti-inflammatory activity in vitro, where they stabilize cell membranes by reducing red blood cell lysis. They also demonstrate the ability to stabilize Human Red Blood Cell (HRBC) membranes, achieving 74.53 % inhibition compared to the standard drug, diclofenac sodium, which showed 83.54 % inhibition. Furthermore, Zn-PBAs enhanced glucose absorption by 8.6 %, with glucose uptake levels increasing from 8.55 % to 81.58 %, compared to the standard drug metronidazole, which ranged from 15.65 % to 88.74 % at concentrations of 10 mu g/mL to 80 mu g/mL. This ability to enhance glucose metabolism suggests Zn-PBAs as promising candidates for the diabetes management. Overall, the findings highlight Zn-PBAs as promising candidates for diverse applications in both energy storage and biomedicine.

Two-dimensional borophene nanosheets are sensitive to oxygen, which has hindered their development and use in scientific research and subsequent applications. Conventional methods of borophene synthesis are based on its epitaxial growth on single-crystal metal substrates by using molecular beam epitaxy (MBE). The electron deficiency of boron atoms in the borophene structure has made the use of metal substrates in the growth process inevitable. Hence, a method to stabilize the borophene sheets for further applications seems necessary. In this work, the oxidation arrangement of Al-activated chemical vapor deposition (CVD) of borophene sheets was investigated via scanning photoemission microscopy (SPEM). This method allows the investigation of oxidation ordering via its high spatial resolution and elemental sensitivity. The results indicate the persistence of the borophene chi 3 (and some beta 12) phase after exposure to air. The formation of boron oxide is primarily limited to the Al aggregated islands and the edges while maintaining the borophene configuration intact. Our results show that the electronic exchange between the Al aggregates and the interface of boron atoms at the edges of the borophene sheet can prevent the oxidation process and preserve the borophene sheets for long periods. The lower oxidation tendency of the Al-saturated borophene was confirmed via density functional theory calculation, showing a lower oxygen binding energy on Al/borophene compared with that of the metal-free borophene. The oxidation-resistive borophene can be exploited in innovative high-efficiency catalytic, electronic, and sensing devices.

Single-photon detectors have gained significant attention recently, driven by advancements in quantum information technology. Applications such as quantum key distribution, quantum cryptography, and quantum computation demand the ability to detect individual quanta of light and distinguish between single-photon states and multi-photon states, particularly when operating within waveguide systems. Although single-photon detector fabrication has been established for some time, integrating detectors with waveguides using new materials with suitable structural and electronic properties, especially at telecommunication wavelengths, creates more compact source-line-detector systems. This review explores the state of the art of single-photon detector research and examines the potential breakthroughs offered by novel low-dimensional materials in this field.

Integrated photonics on Silicon-On-Insulator (SOI) substrates is a well developed research field that has already significantly impacted various fields, such as quantum computing, micro sensing devices, biosensing, and high-rate communications. Although quite complex circuits can be made with such technology, everything is based on a few ’building blocks’ which are then combined to form more complex circuits. This review article provides a detailed examination of the state of the art of integrated photonic building blocks focusing on passive elements, covering fundamental principles and design methodologies. Key components discussed include waveguides, fiber-to-chip couplers, edges and gratings, phase shifters, splitters and switches (including y-branch, MMI, and directional couplers), as well as subwavelength grating structures and ring resonators. Additionally, this review addresses challenges and future prospects in advancing integrated photonic circuits on SOI platforms, focusing on scalability, power efficiency, and fabrication issues. The objective of this review is to equip researchers and engineers in the field with a comprehensive understanding of the current landscape and future trajectories of integrated photonic components on SOI substrates with a 220 nm thick device layer of intrinsic silicon.

Eumelanin is a black-brown biopigment that provides photoprotection and pigmentation in mammals, insects, and invertebrates. It can be obtained by oxidative polymerisation of 5,6-dihydroxyindole (DHI) and its 2-carboxylic acid (DHICA). Due to its unique physical and chemical properties and its biocompatibility, eumelanin is a promising biomaterial for applications in energy storage, biomedicine, and sensing. However, poor solubility in water and lack of sustainable and low-cost sources of eumelanin have so far limited the full exploitation of this biomaterial. Insect farming is rapidly emerging as an alternative source of eumelanin. Unlike other types of eumelanin, BSF eumelanin, which is extracted from the exoskeleton of the black soldier fly (BSF, Hermetia illucens), is water-dispersible; however, its fundamental chemical properties are not completely understood. Here, we report the characterisation of BSF eumelanin using various spectroscopy techniques. Contrary to what is known about other insect eumelanins, which are believed to contain exclusively DHI, our results indicate that BSF eumelanin may contain both DHI and DHICA moieties. We discuss the potential reasons for this discrepancy.

This study conducted a comparative analysis of graphene oxide (GO) surfaces generated using the modified Hummers method at low temperature, employing spheroidal, flake, and micronized graphite with d50 values of approximately 49 mu m, 330 mu m and 7 mu m, respectively. The characterization of the resulting GOs involved TGA, HRTEM, AFM, as well as UV-vis, FTIR, XPS and Raman spectroscopy. Spheroidal graphite produced GO sheets with a thickness of only 1 nm, displaying a zeta potential of -41 mV after 3 h of intercalation and oxidation reaction. In contrast, flake and micronized graphite also yielded 1-nm-thick GO sheets but exhibited a wider size distribution, with zeta potential values of -32 mV and -35 mV, respectively. Moreover, the GO surface derived from spheroidal graphite showed an increased presence of epoxy groups and a reduced concentration of oxidative debris compared to GOs from other graphite types. The curvature of graphite crystals within spheroidal graphite had a more pronounced impact on graphite oxidation than on graphene layer exfoliation. This research highlights the significance of considering graphite sheet curvature as a crucial variable in GO production, providing insights into the novel and noteworthy role that graphite sheet curvature can play in GO materials.

Integrated photonic platforms have rapidly emerged as highly promising and extensively investigated systems for advancing classical and quantum information technologies, since their ability to seamlessly integrate photonic components within the telecommunication band with existing silicon-based industrial processes offers significant advantages. However, despite this integration facilitating the development of novel devices, fostering fast and reliable communication protocols and the manipulation of quantum information, traditional integrated silicon photonics faces inherent physical limitations that necessitate a challenging trade-off between device efficiency and spatial footprint. To address this issue, researchers are focusing on the integration of nanoscale materials into photonic platforms, offering a novel approach to enhance device performance while reducing spatial requirements. These developments are of paramount importance in both classical and quantum information technologies, potentially revolutionizing the industry. In this review, we explore the latest endeavors in hybrid photonic platforms leveraging the combination of integrated silicon photonic platforms and nanoscale materials, allowing for the unlocking of increased device efficiency and compact form factors. Finally, we provide insights into future developments and the evolving landscape of hybrid integrated photonic nanomaterial platforms.

Black soldier fly (BSF) melanin is a new supply of the brown-black pigment eumelanin. Given that eumelanin is a model bioelectronic material for applications such as medical devices and sensors, understanding BSF melanin's electrical properties is important to confirm its viability as an advanced material. Presented here is a systematic, hydration dependent alternating current study of BSF melanin utilising both H2O and D2O vapours. There is a clear difference between the vapours, enabling a thorough analysis including Nyquist plots with model circuit analysis, broad band dielectric spectroscopic modelling as well as applying the Trukhan model to understand free ion concentration and mobility changes as a function of hydration. We find that BSF melanin behaves similarly to previous reports on synthetic systems, and the analysis here sheds additional light on potential charge transport changes. Significantly, a key finding is that there are two different mobility mechanisms for ion transport depending on hydration.

The atomic composition and electronic structure of topological insulators (TI) Bi2Se3 grown by the two-temperature Physical Vapor Deposition on n-type Si patterned substrates, have been followed in details during slight variations of the growth temperatures and values of thickness close to that of the topological transition (about 6 nm), by means of submicron lateral probe photoemission with enhanced surface sensitivity (less than 1 nm). Raman and atomic force microscopy together with Kelvin probe microscopy provide a coherent picture where the fine tuning of Se doping and of the growth temperatures constrain the on–set of the gapless state at the exact middle point of the gap.

Single-photon sources are important for integrated photonics and quantum technologies, and can be used in quantum key distribution, quantum computing, and sensing. Color centers in the solid state are a promising candidate for the development of the next generation of single-photon sources integrated in quantum photonics devices. They are point defects in a crystal lattice that absorb and emit light at given wavelengths and can emit single photons with high efficiency. The landscape of color centers has changed abruptly in recent years, with the identification of a wider set of color centers and the emergence of new solid-state platforms for room-temperature single-photon generation. This review discusses the emerging material platforms hosting single-photon-emitting color centers, with an emphasis on their potential for the development of integrated optical circuits for quantum photonics.

Protein gels prepared by keratin extracted from chicken feathers show potential applications as engineered materials. Feathers are an abundant waste material, whose principal component is keratin, which may have gelling properties not yet sufficiently studied so far which are strongly dependent on the extraction method adopted. The aim of the study is to explore the properties of gels obtained through mercaptoethanol extraction and dialysis process and to evaluate their structural characteristics. The keratin hydrogels were characterized with Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy through which it was possible to identify the secondary structure of the protein on hydrated and dry gel. Moreover, the morphological analysis by scanning electron microscopy (SEM) combined with the rheological analysis showed how the consistency of the gels is maintained on a wide range of loads and frequencies. Furthermore, the biocompatibility of the gels was investigated for the release of subcutaneous drugs using curcumin, an antioxidant polyphenol compound. The fastest release was obtained at pH 7.4, corresponding to physiological conditions.

We investigate the experimentally challenging CrCl3 surface by photon energy dependent photoemission (PE). The core and valence electrons after cleavage of a single crystal, either in a ultra-high vacuum (UHV) or in air, are studied by keeping the samples at 150 °C, aiming at confirming the atomic composition with respect to the expected bulk atomic structure. A common spectroscopic denominator revealed by data is the presence of a stable, but only partially ordered Cl-O-Cr surface. The electronic core levels (Cl 2p, Cr 2p and 3p), the latter ones of cumbersome component determination, allowed us to quantify the electron charge transfer to the Cr atom as a net result of this modification and the increased exchange interaction between metal and ligand atoms. In particular, the analysis of multiplet components by the CMT4XPS code evidenced the charge transfer to be favored, and similarly the reduced crystal field due to the established polarization field. Though it is often claimed that a significant amount of Cl and Cr atomic vacancies has to be included, such a possibility can be excluded on the basis of the sign and the importance of the shift in the binding energy of core level electrons. The present methodological approach can be of great impact to quantify the structure of ordered sub-oxide phases occurring in mono or bi-layer Cr trihalides.