In this paper, we review the 1/f-type noise properties of nanoelectronic devices focusing on three demonstrative platforms: resistive switching memories, graphene nanogaps and single-molecule nanowires. The functionality of such ultrasmall devices is confined to an extremely small volume, where bulk considerations on the noise lose their validity: the relative contribution of a fluctuator heavily depends on its distance from the device bottleneck, and the noise characteristics are sensitive to the nanometer-scale device geometry and details of the mostly non-classical transport mechanism. All these are reflected by a highly system-specific dependence of the noise properties on the active device volume (and the related device resistance), the frequency, or the applied voltage. Accordingly, 1/f-type noise measurements serve as a rich fingerprint of the relevant transport and noise-generating mechanisms in the studied nanoelectronic systems. Finally, we demonstrate that not only the fundamental understanding and the targeted noise suppression is fueled by the 1/f-type noise analysis, but novel probabilistic computing hardware platforms heavily seek well tailorable nanoelectric noise sources.

Introducing suitable electrode materials and electrolytes for supercapacitors and next-generation batteries should be considered for the industrial application of these devices. Among the proposed materials for them, transition metal chalcogenides (TMCs), are attractive and efficient options due to their unique properties such as appropriate layered structure, good oxidation state of transition metals, high thermal and mechanical stabilities, etc. However, applying other layered materials with high electrical conductivity e.g. carbon-based materials can lead to producing remarkable results for the mentioned applications. However, an interesting point is how making TMCs composite with different types of carbon materials leads to improve electrochemical and structural properties of TMCs as active materials. In the present short review, the structural and electrochemical improvements of different types of TMC composites with carbon-based materials and their mechanism are investigated for supercapacitors and next-generation rechargeable batteries.

Near-infrared (NIR) photons are expanding advanced applications in optoelectronics. However, while 2D materials like graphene offer an attractive route for NIR photodetection, the alternative for high-performance NIR detection is still evolving. Hence, solution-processed n-Bi2Se3 /p-Si-based 2D heterojunction photodiodes have been fabricated here and used for high-performance NIR detection. Further, we report high photoresponsivity of 248 mA W−1 at 1100 nm, high external quantum efficiency of 22, 23 and 28% for Ag-loaded (at 5, 7.5 and 10%) Bi2Se3 and good stability. The chemical states of Bi2Se3 and Ag are detected using the core-level spectra of x-ray photoelectron spectroscopy. Photoresponse I–V characteristics are investigated under both dark and illumination; the high photocurrent achieved for Ag-loaded Bi2Se3 and the increase in the forward photocurrent under both dark and bright conditions are reported. The temporal photoresponse curve confirms the good stability (photoswitching behavior) and reproducibility with a response time of 0.74 s and a decay time of 0.18 s. Therefore, these unique performance and device parameters of a manufactured photodiode strongly recommend as a potential heterojunction photodiode for an NIR photodetector.

We study the impact of Al oxide/Poly(methyl methacrylate) (PMMA) interface on plasmonic emission enhancement of infrared semiconductor quantum dots (QDs). For this, PbS QDs embedded in PMMA matrix are deposited on the top of heterostructures consisting of a Au thin film, a dielectric spacer, and an ultrathin layer of Al oxide. Our results suggest that such structures can support an emission enhancement far more than what can be reached in the cases when the QDs/PMMA films are placed on Au thin film/dielectric spacer directly, i.e. in the absence of the Al oxide. We also demonstrate that Au/Si/Al oxide/PMMA heterostructures can increase the photo-induced fluorescence enhancement of PbS QDs, making them brighter as they are irradiated with a laser field. We discuss these results in terms of combined effects of plasmonic field enhancement (Purcell effect) and the carboxylate anion bonds formed at the Al oxide/PMMA interface.

The development of efficient photodetectors for color recognition is of great importance for many applications. In this paper, we report a novel bipolar dual-broadband photodetector equipped with a perovskite heterojunction, with bidirectional broadband responses in the short-wavelength and long-wavelength regions at zero bias voltage, enabled by a charge separation reversion mechanism. The unique aerosol–liquid–solid technique allowed the perovskite heterojunction to be fabricated by successively depositing wide-bandgap perovskite (WBP) and narrow-bandgap perovskite (NBP) layers directly on the transparent substrate. For photodetectors based on the perovskite heterojunctions, the short-wavelength photons were depleted by the bottom WBP layer and generated negative responses, while the long-wavelength photons were absorbed by the top NBP layer and generated positive responses. Moreover, the demarcation wavelength between the bipolar responses and the cut-off wavelength can be easily tuned by adjusting the bandgaps (or compositions) of the bottom and top perovskite layers.

Neuromorphic circuits based on spikes are currently envisioned as a viable option to achieve brain-like computation capabilities in specific electronic implementations while limiting power dissipation given their ability to mimic energy-efficient bioinspired mechanisms. While several network architectures have been developed to embed in hardware the bioinspired learning rules found in the biological brain, such as spike timing-dependent plasticity, it is still unclear if hardware spiking neural network architectures can handle and transfer information akin to biological networks. In this work, we investigate the analogies between an artificial neuron combining memristor synapses and rate-based learning rule with biological neuron response in terms of information propagation from a theoretical perspective. Bioinspired experiments have been reproduced by linking the biological probability of release with the artificial synapse conductance. Mutual information and surprise have been chosen as metrics to evidence how, for different values of synaptic weights, an artificial neuron allows to develop a reliable and biological resembling neural network in terms of information propagation and analysis.

Designing low-cost, Earth-abundant, and non-precious catalysts for electrochemical water oxidation reactions is particularly important for accelerating the development of sustainable energy sources and, further, can be fed to fuel cells. In the present work, we report the oxygen evolution reaction (OER) activity of a metal-oxide catalyst, Mn3O4, and study the effect of transition metal doping (Cu and Fe) on the OER activity of Mn3O4 in an alkaline medium. The Mn3O4 and transition metal (Cu and Fe) doped Mn3O4 catalysts were prepared using a hydrothermal reaction technique. Powder x-ray diffraction studies revealed that these compounds adopt a tetragonal spinel structure with an I41/amd space group, and this is further supported with Fourier transform infrared spectroscopic measurements. These results are further supported by high-resolution transmission electron microscopic measurements. The electrochemical measurements of these catalysts reveal that the transition metal (Cu and Fe) doped Mn3O4 catalysts show better OER activity than pristine Mn3O4 (MO). The transition metal (Cu and Fe) doped Mn3O4 catalysts exhibit lower overpotential for the OER (η MCO = 300 mV and η MFO = 240 mV) than the MO (η MO = 350 mV) catalyst. The better performance of Fe-doped Mn3O4 is further supported by turnover frequency calculations.

Efficient electrocatalysts are critical for the oxygen evolution reaction (OER) that occurs during water electrolysis. Herein, a simple and low-cost strategy of assembling CoNi nanowire arrays with NiFe nanosheets on flexible carbon cloth (CC) support as an efficient OER catalyst is developed. This unique ‘nanosheets on nanowires’ structure design increases its specific surface area, enabling access to more active sites. The resulting NiFe@H-CoNi/CC catalyst exhibits excellent OER activity (280 mV overpotential at 100 mA cm−2) with a Tafel slope of 36 mV dec−1 and also has outstanding durability at high current operation conditions (over 100 h at 100 mA cm−2). Moreover, in-situ Raman analysis suggests that the NiOOH is the realistic OER active phase. This ‘nanosheet on nanowire’ design gives a means for fabricating OER catalysts that are both high-performance and long-lasting.

Noble-metal-decorated semiconductor photocatalysts have attracted noticeable attention due to their enhanced photocatalytic activity. Herein, we have synthesized the pure rutile phase of TiO2 nanorods, with microflower morphology, using a hydrothermal method and decorated them with Au to observe plasmon-induced enhanced photocatalytic efficiency. The optical bandgap engineering through Au-decorated TiO2 introduces midgap states that help with charge compensation during photodegradation studies. The surface plasmonic resonance peak of Au is observed together with the defect peak of TiO2, extending the absorption of the solar spectrum from the UV to the visible region. The quenching in photoluminescence intensity with increased Au thickness indicates the formation of a Schottky junction at the interface of Au and TiO2 that helps to reduce photogenerated charge carrier recombination. The softening of the E g Raman mode and photothermal effects originate from the nonradiative decay of localized surface plasmons through electron–phonon and phonon–phonon relaxation. The photocatalytic degradation of Rhodamine 6G is monitored by exposing the sample to UV and visible light sources under Raman spectroscopy. The Au decoration plays a crucial role in promoting charge separation, Schottky junction creation, photothermal effects, and UV to visible light absorption to enhance photocatalytic activity, which can be explained on the basis of the charge transfer mechanism. Our in-situ photodegradation study at the interface of noble metal and semiconducting materials will pave the way toward improving the understanding of plasmon-enhanced photocatalytic applications.

Moiré patterns (MPs), arising from the superposition of two lattices with close periods, are tightly related to the physicochemical properties of bilayer nanostructures. Here, we develop the theory of complex MPs emerging in twisted bilayer graphene and planar nets of double-walled nanotubes at significant relative twist and/or deformation of layers. The proposed theory clarifies the physicochemical regularities arising at sorting of single-walled carbon nanotubes (SWCNTs) by organic molecules, which self-assemble in regular coatings on both the tubes and planar graphene. We introduce and consider an outer tubular virtual lattice that is a parent structure for the deposited coating and due to this fact, its existence is crucial for the coating formation. As we show, such outer lattices exist only for successfully sorted SWCNTs and the superposition between the outer lattice and SWCNT forms a specific long-period MP. We explain known experimental results of SWCNT sorting by molecules of flavin group, poly(9,9-dioctylfluorene-2,7-diyl), and poly [(m-phenylenevinylene)-alt-(p-phenylenevinylene)]. Also, our approach points out other organic molecules and polymers suitable for effective carbon nanotube sorting.

Two-dimensional transition metal dichalcogenides are regarded as the ideal hosts for zinc-ions. Herein, a facile hydrothermal method is proposed to fabricate the metallic phase (1T phase) MoS2/multi-walled carbon nanotube (MWCNT) hybrids serving as the cathode materials for zinc-ion batteries (ZIBs). By virtue of the exertion of phase engineering and the synergy between the 1T MoS2 nanosheets and MWCNT framework, the transfer kinetics of zinc-ions of the prepared hybrid are remarkably accelerated, leading to boosted electrochemical properties at both room temperature and low temperatures. The hybrid electrode delivers a high reversible capacity of 161.5 mAh g−1 after 100 cycles at 0.1 A g−1, and good cycling stability with a desired capacity retention of 84.6% over 500 cycles at 1 A g−1. Furthermore, its boosted capability of zinc-ion storage in a low-temperature atmosphere is revealed. This work not only provides an effective way to squeeze the values of phase engineering of MoS2 in ZIBs, but also reveals the great potential of MoS2-based composites in low-temperature energy storage devices.

We present a one-step hydrothermal synthesis of hybrids consisting of nickel sulfides in the form of Ni3S4–NiS (NN) and Ni3S4–NiS-rGO (NNR), i.e. with the addition of reduced graphene oxide (rGO), for application as catalysts. After accurate physical characterization and confirmation of successful synthesis, we evaluate the ability of these catalysts in the processes of methanol and ethanol oxidation. The precise electrochemical analyses show relatively good potential and excellent cyclic stability in methanol oxidation reaction (MOR) and ethanol oxidation reaction (EOR) processes. The comparison of the two catalysts shows the superiority of NNR over NN, confirming that rGO introduces a higher specific surface area and a higher electrical conductivity in the NNR structure. In the process of MOR, NNR has an oxidation peak at a current density of 55 mA cm−2 and a peak potential of 0.54 V. In EOR, this peak is located at a current density of 11 mA cm−2 and at a peak potential of 0.59 V. NNR has 97% and 94% stability in MOR and EOR after 1000 consecutive cycles, respectively, which are acceptable values.

Lignin is a natural renewable biopolymer with abundant reserves and great potential. As a by-product of the pulp and paper industry, the world can produce 150 billion tons of it every year, but it has not been effectively utilized. It was found that disordered and complex lignin can be converted into ordered and homogeneous nanoparticles by self-assembly, solvent exchange and acid precipitation. Lignin nanoparticles (LNPs) have the advantages of high stability, high activity, good biocompatibility and biodegradability, as well as improved structural and size control, antioxidant activity and other properties. LNPs have great potential for application not only as a natural alternative to traditional petroleum derivatives, biopharmaceutical carriers, but also in hydrogels. In recent years, the research of LNPs has received a lot of attention. It is hoped that more economical, environmentally friendly and high yielding methods for the synthesis of LNPs will be investigated in the future. This paper reviews the preparation methods of LNPs and their applications in various fields.

In recent years, two-dimensional (2D) plate materials have become the most attractive class of candidate materials for a wide range of potential applications due to their unique structural characteristics and physicochemical properties. Starting from graphene, 2D plate materials have become a large family with many members and diverse categories. Especially in recent years, we have made some significant breakthroughs in the field of 2D materials. Langmuir–Blodgett (LB) technology is an advanced technology for preparing ultrathin films with highly ordered molecules by using its unique dynamic interface in the preparation process, which can effectively control and adjust the film material with layered nanostructures. With the advancement of LB technology, different thin film materials need to be prepared to realize various functions. This paper summarizes the research progress and future perspectives of LB technology based on 2D materials.

Graphene-based thermal rectification was investigated by measuring the thermal transport properties of asymmetric suspended graphene nanomesh devices. A sub-10 nm periodic nanopore phononic crystal structure was successfully patterned on the half area of the suspended graphene ribbon by helium ion beam milling technology. The ‘differential thermal leakage’ method was developed for thermal transport measurement without disturbance from the leakage of electron current through the suspended graphene bridge. A thermal rectification ratio of up to 60% was observed in a typical device with a nanopore pitch of 20 nm. By increasing the nanopore pitch in a particular range, the thermal rectification ratio showed an increment. However, this ratio was degraded by increasing the environmental temperature. This experiment suggests a promising way to develop a high-performance thermal rectifier by using a phononic crystal to introduce asymmetry on homogeneous material.

Recently, single-atom catalysts (SACs) have been found to be promising candidates for oxygen electrocatalysis in rechargeable lithium–oxygen batteries (LOBs) owing to their high oxygen electrocatalytic activity and high stability, which originates from their unique coordination environments and electronic properties. As a new type of catalyst for LOBs, the advancements have never been reviewed and discussed comprehensively. Herein, breakthroughs in the design of various types of SACs as cathode catalysts for LOBs are summarized, including Co-based, Ru-based, and other types of SACs. Moreover, considerable emphasis is placed on the correlations between the structural feature of the SAC active sites and the electrocatalytic performance of LOBs. Finally, an overview and challenges of SACs for practical LOBs are also provided. This review provides an intensive understanding of SACs for designing efficient oxygen electrocatalysis and offers useful guidelines for the development of SACs in the field of LOBs.

The present work focuses on the synthesis and characterization of a sugar-glass nanoparticle (SGnP) based reservoir type protein delivery system pertinent to tissue engineering applications. The SGnP nanocarriers were prepared via inverse micelle of sodium bis(2-ethylhexyl) sulfosuccinate based on an anionic surfactant and subsequent flash-freezing technique. Initially, a total of five different grades of protein-free SGnPs have been prepared to examine the effects of systematic changes in starting concentrations of the aqueous phase, organic solvent, the molar ratio of water, and surfactant in controlling the size, shape, and uniformity of micelles. Evidently, the Fourier transform infrared (FTIR) and scanning electron microscope (SEM) results confirmed that the SGnP can be successfully prepared. Subsequently, SGnP based protein depot has been validated using bovine serum albumin (BSA), horseradish peroxidase (HRP) and growth and differentiation factor-5 (GDF-5). The particle size, morphology, protein encapsulation efficiency and in vitro release kinetics were assessed using SEM, FTIR, UV–visible spectroscopy and Bradford protein assays. Excellent encapsulation efficiency (93%–94%) and sustained release behaviour of BSA (∼22% protein release after 14 d) and GDF-5 proteins (∼29% protein release after 30 d) were exhibited by the optimal grades of SGnP constructs with an average particle size of 266 nm and 93 nm, respectively. Furthermore, FTIR, differential scanning calorimeter (DSC), polyacrylamide gel electrophoresis (PAGE) and NATIVE-PAGE studies results confirm successful encapsulation, stability and preserving the structural integrity of proteins placed into the core of the SGnP constructs. Evidently, a very high (93%) residual HRP enzyme activity signifies the capability of our SGnP system to protect the encapsulated proteins from process-related stresses. In vitro cytotoxicity and fluorescence cell morphology analyses using human adipose-derived mesenchymal stem cells affirmed good cytocompatibility of protein encapsulated SGnP. Overall, the study findings indicate SGnP nanocarrier-mediated protein delivery systems as a promising approach complementary to conventional techniques in tissue engineering and therapeutic applications.

Photocatalytic degradation has been demonstrated to be an efficient and eco-friendly method for the removal of dye pollutants. Herein, we report the synergetic effect of glutathione (GSH)-capped AgInS2-ZnS (AIS-ZnS) core–shell quantum dots (QDs) and titanium dioxide (TiO2) as a novel nanocomposite for the efficient photocatalytic treatment of methylene blue (MB). The AIS-ZnS core–shell QDs and the corresponding QD/TiO2 nanocomposites were synthesized directly in an aqueous medium followed by annealing. The optical properties of the AIS-ZnS core–shell QDs showed strong yellow photoluminescence, which decreased gradually with the addition of TiO2. Fourier transform infrared (FTIR) spectroscopy confirmed the GSH capping on the QDs and nanocomposites. X-ray diffraction and transmission electron microscopy revealed the nanocrystalline nature and shape of the as-synthesized materials and showed the integration of the QDs (3.9 nm) on the TiO2 particles after annealing. These materials were then investigated as a photocatalyst for MB degradation using visible light irradiation. The effect of TiO2 content in the catalyst, calcination, photoirradiation period, catalyst dose, and initial MB concentration on photodegradation of MB was studied. The results indicated that the AIS-ZnS QD/TiO2 nanocomposite exhibited better photodegradation performance compared to AIS-ZnS QDs and TiO2. The increasing TiO2 concentration in the nanocomposite also enhanced MB degradation efficiency (up to 99%). The kinetics of MB degradation follows a pseudo-first-order process. The prepared AIS-ZnS QD/TiO2 nanocomposite would serve as an effective and eco-friendly photocatalyst for MB degradation.

Conventional doping processes are no longer viable for realizing extreme structures, such as a δ-doped layer with multiple elements, such as the heavy Bi, within the silicon crystal. Here, we demonstrate the formation of (Bi + Er)-δ-doped layer based on surface nanostructures, i.e. Bi nanolines, as the dopant source by molecular beam epitaxy. The concentration of both Er and Bi dopants is controlled by adjusting the amount of deposited Er atoms, the growth temperature during Si capping and surfactant techniques. Subsequent post-annealing processing is essential in this doping technique to obtain activated dopants in the δ-doped layer. Electric transport measurement and photoluminescence study revealed that both Bi and Er dopants were activated after post-annealing at moderate temperature.

Titanium dioxide (TiO2) and holmium-doped titanium dioxide (Ho-TiO2) nanoparticles(NPs) were synthesized through a sol gel route. The synthesized NPs were characterized by ultraviolet-visible (UV–Vis) spectroscopy, x-ray diffraction (XRD), energy dispersive x-ray analysis, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, and photoluminescence (PL) spectroscopy. DNA binding, antibacterial, hemolysis, and antioxidant assays of the synthesized NPs were also carried out in order to find their therapeutic applications. Successful doping of TiO2 with Ho reduced the bandgap from 3.10 to 2.88 eV. SEM and XRD analysis showed that both TiO2 and Ho-TiO2 NPs exhibit a tetragonal structure and the morphology of the particles improved and agglomeration reduced as a result of doping. The PL emission intensity of TiO2 also reduced with doping. The degradation of Safranin O dye over both the catalysts followed first-order kinetics. The calculated activation energy for the photodegradation of the given dye was found to be 51.7 and 35.2 KJ mol−1 for bare TiO2 and Ho-TiO2 NPs, respectively. After 180 min, 84% and 87% dye degradation was observed using pure TiO2 and Ho-TiO2, respectively. A high percent of degradation of the dye was found at a low concentration (20 ppm) and at optimal dosage (0.035 g) of both the catalysts. The rate of Safranin O dye degradation was found to increase with an increase in temperature and pH of the medium. A DNA binding study revealed that Ho-TiO2 NPs are more capable of binding to human DNA. An antibacterial activity study showed that Ho-TiO2 NPs were more efficient against both gram-negative and gram-positive bacterial strains compared to pure TiO2. Hemolysis assay showed that TiO2 and Ho-TiO2 NPs are non-biocompatible. Ho-TiO2 NPs showed higher anti-oxidant activity compared to bare TiO2.