Population growth increases the disposal of organic pollutants in aqueous environments, including anionic and cationic dyes. Tungsten trioxide (WO3) and copper tungstate (CuWO4) have been considered as photocatalysts for the degradation of these pollutants by photoelectrocatalysis. However, these semiconductors used individually have some properties that reduce their potential for application in photoelectrocatalysis. Thus, this work proposed the in-situ synthesis of a WO3/CuWO4 heterojunction film for photoelectrocatalysis of anionic and cationic dyes. The structural characterization showed the monoclinic and triclinic phases in the nanocomposite corresponding to WO3 and CuWO4, respectively. The optical characterization revealed a better visible light absorption for the heterojunction film. The film formed nanoplates grown perpendicular on the conductive substrate, which can mitigate the charge recombination process. The photoelectrochemical characterizations showed superior photoelectrochemical stability for the WO3/CuWO4 film and the best activity to remove cationic dyes.

Bismuth–carbon-based materials have recently gained much attention because of their excellent physicochemical properties, possessing favourable characteristics for many crucial applications. Recent literature has documented several achievements, especially on the degradation of drugs and dyes. Regarding the potential applications of bismuth carbon-based photocatalytic materials for wastewater treatment-based environmental remediation, no study has been performed. The outstanding characteristics of carbon materials, including their distinctive nanocrystal formations, high electrical conductivity, inherent hydrophobicity and customizable surface properties, make them ideal for various catalytic techniques, including photocatalysis. Bismuth–carbon-based compounds are available in nature and are ecologically beneficial, making them an excellent alternative to conventional photocatalysts. The goal of this review is to present a thorough analysis of the current developments of the various bismuthal materials and the synthesis of bismuth carbon-based photocatalysts, with a particular focus on the possibilities for the photodegradation of a variety of organic contaminants. Initially, numerous synthetic methods, various bismuthal materials and the properties of carbon materials are methodically discussed. Recent developments are highlighted in the manufacturing of bismuth–carbon-based materials for photocatalytic performance applications.

The synthesis and modification of polymeric carbon nitride nanosheets (NPCN) and their exploration toward enhanced thermal and mechanical properties of acrylonitrile butadiene styrene (ABS) nanocomposites are described. Polymeric carbon nitride was synthesized by the thermal treatment method and subsequently modified using polydopamine (PDA) through a simple chemical treatment. Both raw and modified fillers (NPCN and PDA@NPCN) were characterized using detailed spectroscopic analyses. The modified filler was then used to fabricate composites with an ABS polymer matrix, targeting the improvement of various properties of the resulting nanocomposites. Although NPCN has been used to modify various polymer matrices, NPCN modified with polydopamine via. non-covalent interactions has not been reported to date for modifying the properties of polymers. Here, the non-covalent interaction developed via a promising eco-friendly bioinspired method has a positive impact on improving the performances of the ABS matrix. The major objective of the current study is to investigate the interfacial interaction between polydopamine modified polymeric carbon nitride nanosheets and the ABS matrix, and to determine its influence on the thermal, frictional and mechanical performance of the developed nanocomposite. Preliminary analyses indicated the successful incorporation and interaction between PDA@NPCN and ABS. The mechanical studies of the nanocomposites revealed that the tensile strength and frictional behavior improved up to 29 and 51%, respectively, with the lower addition of PDA@NPCN content. Pyrolysis-combustion flow calorimetric studies showed that NPCN had no negative effect on the flammability of ABS. This approach finds potential applications in enhancing the bearing nature of the polymer system without affecting its thermal stability and flammability.

Zinc oxide (ZnO) is known to exhibit multifunctional properties for a variety of applications, including gas sensing, light-emitting diodes, optoelectronics and transparent electronics. Doping in ZnO may induce defect states, thereby influencing its physical properties. Here, the simultaneous substitution with Al and Cu is attempted in ZnO in order to tune its optical properties. The morphological, structural, optical and photoluminescence properties were thoroughly investigated using different characterization tools. The phase purity of the Al and Cu co-doped ZnO nanoparticles is confirmed by X-ray diffraction, Fullprof, XPS and Raman spectroscopy. The nanoparticles possess an agglomerated spherical-shape-like morphology, as evident from SEM images. The co-doped ZnO nanoparticles reveal a band gap of ∼3.2 eV. Photoluminescence and time-resolved photoluminescence spectroscopy show the presence of various defect states in ZnO which can tune its optical properties as per the desired application.

We have investigated the dependence of the magnetization switching behavior on the structure, size and nonmagnetic Cu layer thickness (tCu) in Ni/Cu/M (M = Ni, Co) cylindrical nanowires fabricated by electrodeposition using porous polycarbonate templates. The crystal structure of the Ni nanowires was (111)- or (200)-oriented polycrystalline fcc, while that of Co nanowires was (100)- or (101)-oriented hcp and/or (111)-oriented polycrystalline fcc. When the wire diameter (d) was 50 nm, the squareness ratio (Mr/Ms) for M = Ni, as estimated from the magnetization curve, is almost constant at Mr/Ms∼0.79 (Mr/Ms∼0.64 for M = Co) when tCu increases from 0 to 500 nm. When d=100nm, Mr/Ms decreases by 41% from 0.71 to 0.42 with increasing tCu from 0 to 700 nm for M = Ni, while Mr/Ms decreases by 25% from 0.53 to 0.40 with varying tCu from 0 to 500 nm for M = Co. The threshold Cu layer thickness (tCuth) beyond which Mr/Ms becomes constant at d=100nm is ∼500 nm for M = Ni and ∼300 nm for M = Co. The results are qualitatively consistent with those obtained from our micromagnetic simulation and analysis. The observed difference in the tCuth dependence of Mr/Ms between M = Ni and Co is attributed to the change in the magnetic domain structure of the nanowires as it sensitively varies with the magnetocrystalline anisotropy. On the other hand, the coercive force of the nanowires shows a small tCu dependence for both d=50 and 100 nm. These results indicate that the layered structure in the nanowires governs the magnetic domain structure, though the effect on the magnetization switching behavior is indeed relatively small.

Today, there is a continuous rise in the requirement for upgraded healthcare systems that are self-driven, dynamic and very low in maintenance. With a steep rise in the evolution of devices and their applications, such as sensors, there is an increment in the supply of sustainable energy without the replacement and recharging of the installed charge storage devices. Among the various energy scavengers, triboelectric nanogenerators (TENGs) have garnered huge attention as they have a high instantaneous output power and can be developed from a broad selection of available materials, like aluminium (Al) and copper (Cu) metal films, fluorinated ethylene propylene (FEP), polytetrafluoroethylene (PTFE) and green materials like cellulose-based materials. TENGs have a great ability to convert extracted mechanical energies into electrical energies very effectively due to the coupling effects of contact electrification and electrostatic induction. They have tremendous potential in a diverse range of applications, such as medical therapies that include biomedical applications, energy scavenging and active sensing. TENGs are devices made of self-energizing materials that are non-polluting, long-lasting and small sized. They can be developed through inexpensive fabrication processes and are environmentally friendly. In this paper, the mechanism by which the triboelectric nanogenerators perform their applications and how strategies are being developed to improve their performance have been discussed. We have also discussed the future research directions that are being undertaken to advance development in this field. So far, TENGs have mainly been used as mechanical and chemical stimuli to detect sensors and as an electrical source for electronic equipment and devices. Most of the studies found in the literature have reported that TENGs are primarily focused on optimization of systems and circuit designs or on the application of TENGs. A thorough review of the fundamentals of TENGs has been presented here.

Dealloying is already being used as a method for manufacturing structured binary and multicomponent metal nanoparticles. In such a process, one of the metals, e.g. the less noble one, is selectively removed from the alloy, while the atoms of the more noble metal diffuse and reorganize into a particular structure, e.g. a porous structure or a core–shell structure. Usually, dealloying is provided by an electrochemical method. Binary Ni–Pt and Cu–Pt nanoparticles with an initial number of atoms N = 3000, equiatomic composition and uniform distributions of components over the volume were chosen as objects of atomistic simulations. In the course of simulation, Ni or Cu atoms, respectively, were gradually removed until 1200 atoms were removed. For the removal, at each step of the iterative process, an atom with the smallest absolute value of the potential energy was selected. The simulation was carried out using two alternative simulation methods (molecular dynamics (MD) and Monte Carlo (MC)). An integrated approach to the simulations allows us to increase the reliability of the results and to prevent the appearance of artifacts. The interatomic interaction in the simulated systems was described by the many-particle Gupta potential (tight-binding potential). A drop in energy was observed for Cu–Pt nanoparticles, while for the Ni–Pt nanoalloy, the MD method predicts a similar behavior, but the MC method predicts an increase in the energy of the nanoclusters after the removal of 400 atoms. Analysis of the structure showed that, at this moment, active pore formation begins in the Ni–Pt nanoparticles, both in the surface layers and in their central regions.

In this paper, ion irradiation of thin metallic layers is reviewed. The main phenomena occurring are dewetting of the layer into spheres, alongside diffusion, ballistic ejection and precipitation of satellite nanoparticles. When irradiation is pursued long enough, the nanoparticle population created by dewetting reduces its mean size due to ballistic mixing. Eventually, if the dose rate is high enough, this population size will stabilize with the satellite precipitate size. The resulting mean radius depends on the balance between retro diffusion and ballistic ejection. As the ballistics effects could be scaled by ion beam parameters (intensity, ion type, energy, …) these phenomena could technically be used to tailor the size of the nanoparticles. This would have applications in the plasmonic field as nanoparticles’ optical properties are determined, among other things, by their size.Next, different models concerning nanoparticle size evolution during irradiation are discussed. Among these models, one is compared to experimental data from the literature. Our model is then added to increase compliance with experimental data.

In this study, a new concept is explored for an electrolyte-free microcapacitor fabrication based on mesoporous silicon (mPSi) and zinc oxide (ZnO) electrodes, separated by aluminum oxide (Al2O3) as a dielectric layer. For this conception, we gathered various techniques in order to have the best system, namely: •Electrochemical etching to form mPSi.•Aluminum (Al) thin film deposited on mPSi by physical vapor deposition (PVD).•Oxidation of Al in a rapid thermal processing (RTP) furnace heated to 600 °C under pure oxygen gas injection for 300 s.•Coating the ZnO layer on the assembly electrochemically. The designed device was characterized under DC and AC currents with a specific capacitance of 160 nF/cm2 for a DC of 40 nA/cm2, low series resistance (38.7 Ω) and high ohmic resistance (1.69 MΩ). The latest value of Rox indicates a very high ohmic resistance across the Al2O3 dielectric layer. The studied device shows good stability for galvanoplastic charge–discharge cycles exceeding 1200 cycles with an efficiency of about 60%. In AC, the decrease of the capacitance values with a frequency increase indicates the presence of numerous charge traps near the interface of Al2O3 with the electrodes. The conductance measurements demonstrate a high interface state density (Nss) value of 1.6 × 1012 cm−2. The calculated leakage current was about two to three times higher than that obtained in the literature.

We have used the electrospinning method to fabricate a polyvinylidene fluoride (PVDF) membrane, bismuth vanadate-polyvinylidene fluoride (BiVO4-PVDF, referred to as BV-PVDF) and bismuth vanadate-reduced graphene oxide-polyvinylidene fluoride (BV-rGO-PVDF) composite membranes. Compared to costly noble metals such as platinum (Pt), rGO is a more economical and ecologically friendly alternative for enhancing photocatalytic activity. After characterization, the fiber membranes were used as a catalyst material to investigate the relationship between the structure and catalytic activity with a 10 ml solution of 5 mg/L methylene blue (MB) dye. Furthermore, ethylenediaminetetraacetic acid (EDTA), benzoquinone (BQ) and isopropanol (IPA) scavengers were utilized to investigate the degradation intermediates. It has been discovered that the electrospun BV-rGO-PVDF composite has piezocatalytic and photocatalytic capabilities that are superior to those of PVDF and BV-PVDF. The degradation process is carried out with MB as a model dye, and we discovered that the BV-rGO-PVDF composite leads to a maximum dye degradation of 82% in under 180 min of process time, with a degradation rate of 0.0088 min−1. Consequently, we concluded that the hybrid 1D structure of the piezocatalytic and photocatalytic material is appropriate for the breakdown of organic contaminants.

Anodization of titanium is used to form dual scale nanoporous titanium oxide surfaces (NanoTi) that are highly stable, relatively low cost and exhibit unique optoelectronic properties. Due to their high biocompatibility, electrical conductivity and surface area, NanoTi surfaces also promise to be useful electrode materials for biosensors. In this study, we investigated the feasibility of using NanoTi surfaces as a size-selective electrode material for the detection of nano-sized objects. Gold nanoparticles ranging from 16 to 69 nm in diameter were used to model the binding behaviors of bioanalytes, such as enzymes, exosomes and viruses. A size-dependent, steric-like exclusion phenomenon appears to determine the binding location of the nanoparticles within the dual scale nanostructure present on the NanoTi surfaces. Nanoparticles smaller than the pore diameter were observed to bind to ridges between pores, while larger nanoparticles bound onto the pores. The binding events were monitored by Electrochemical Impedance Spectroscopy (EIS), which highlighted that the electrochemical signal measured was dependent on the location of the nanoparticle upon binding. On-pore binding reduced the overall system resistance, while on-ridge binding increased it. These proof-of-concept results indicate that NanoTi surfaces could be used in the development of electrochemical sensors that intrinsically promote the binding of a nano-analyte within a certain size range.

An increasing number of scientific publications on magnetic quantum dots (MQDs) have revealed the growing interest of scientific society in this area. MQDs with a size of a few nanometers can show the quantum confinement effect far superior to their bulk counterparts. Quantum confinement enhances the energy of a particle, which depends on excitonic processes and can dramatically change the optical properties of a QDs. Magnetic quantum dots are the combination of the ability of two materials (magnetic nanoparticles and quantum dots) which respond as a universal tool for theragnosis. This review summarizes the optical and magnetic properties of magnetic quantum dots that permit visualization, imaging, magnetic separation and may have a therapeutic benefit. It also highlights the recent advances made in the research field of multifunctional magnetic quantum dots in catalysis, sensor, magnetic resonance imaging, cancer treatment and environmental remediation. Challenges still exist with QDs, especially a major obstacle is toxicity when contemplating various applications.

Hydrothermal synthesis was used to obtain pure, doped and composite semiconductor oxide materials. We synthesized ZnO, CuO, Cu doped ZnO with 1, 2 and 3 wt %, and for Cu additions at 6, 8, 10, 15, 30 and 50 wt% this resulted in ZnO–CuO composites with different morphologies. X-ray diffraction (XRD) showed hexagonal and monoclinic crystalline phases for pure ZnO and CuO, respectively. Electron microscope images showed two-dimensional (2D) shaped particles. The Cu element could dope ZnO up to 3 wt%, whilst above this value, composites of ZnO–CuO were generated, with two segregated phases having flake-like shaped elongated particles. The visible-light absorption increases for the doped samples, being directly proportional to the Cu content for the dopant and the composite particles, showing a broad absorption range between 200 and 800 nm. Two bandgap energy values of 3.22 and 1.45 eV were determined for the ZnO–CuO samples. The samples were studied by X-ray photoelectron spectroscopy (XPS) in order to understand the doping process and composite formation.

With a focus on catalysis, pollution and energy, this review presents significant and insightful methodological advancements and techniques in the field of applied nanotechnology. We investigate novel nanomaterials, such as “smart” metal–metal oxides (MeOs) and Metal Organic Frameworks (MOFs), for their contribution to sustainable and renewable resources in light of detrimental climate change and the depletion of fossil fuels. Researchers have spent the last ten years creating novel and fundamental chemistries that will revolutionize the field of nanotechnology and benefit the human race. This transition is driving the investigation of green chemistry to mitigate environmental problems, replace traditional methods with novel designs and ultimately replace unsustainable chemistries. The review aims to discusses various synthetic strategies for developing transition metal, carbon material and electrocatalysts in storage and conversion systems. With this consideration, the preparation of catalytically-active bio-inspired MeOs (Cu/Cu2O/CuO and Cu/Cu2O/CuO/ZnO) and MOFs (Zr-MOFs and Fe-MOFs) using plant biological entities and waste materials as an eco-friendly, green route are explored. Meanwhile, innocuous solvents like water and cheap, renewable and recyclable starting materials such as polyethylene terephthalate (PET) are conferred to ensure sustainability for large scale MOF production and commercialization.

The present work involves a method for synthesizing metallic Ti nanoparticles in the liquid phase. A deep eutectic solvent (DES) composed of ethylene glycol and choline chloride was used as the solvent for electrolytic dissolution. A nanoparticle colloid solution was prepared from a titanium chloride/DES solution by a flowing electric current, where metallic Ti plates were used as the anode and cathode under ultrasonic irradiation in water at room temperature. The nanoparticulate powder had the crystal structure of hexagonal Ti. The nanoparticle sizes were in the range 4.0–114.0 nm and the metallic Ti nanoparticles were chemically stable in ambient atmosphere. Chemically stable metallic Ti nanoparticles are expected to be applied in fields such as aeronautics, solar cells, molding, etc.

In the present work, a visible to ultraviolet C (UVC) up-conversion Er3+ doped yttrium aluminium garnet (YAG) ceramic phosphor was developed by a high temperature solid state reaction method. The structural characterization of the prepared phosphor was carried out using X-ray diffraction analysis and transmission electron microscopy techniques. The up-conversion behaviour of the phosphor was studied by recording the emission spectra of the phosphor under a 460 nm blue LED source. The emission spectrum was obtained in the UV region containing peaks centred at 217, 256, 275 and 312 nm. The emitted UV radiation belongs to the germicidal UV wavelength; therefore this behaviour of the phosphor was applied for the inactivation of surface born microbes through the emitted radiation. The emission behaviour of the phosphor was further investigated by LED encapsulation. The up-conversion emission increases with an increase in the crystal size.

The availability of a simple, economical and well-controlled method for producing nanoparticles is beneficial to researchers working in various fields of nanotechnology. Many top down and bottom up physical and chemical production processes have been developed for the commercial manufacturing of nanoparticles, however, the bulk of these processes require complex precursors and procedures that affect the performance and applicability of the generated nanomaterials. Additionally, these processes are often expensive, labour-intensive and environmentally harmful. In this study, a novel, well-controllable and economical approach to produce oxide nanoparticles has been established. Iron–nickel nano-oxides were synthesized in order to support the feasibility of the developed method. The generated iron–nickel oxide nanoparticles showed a quite narrow particle size distribution, with the majority of the collected particles falling in the size range between 3 and 15 nm, with a median size of about 5 nm. These produced materials are effective and sought-after candidates for a variety of commercial applications, including catalysis, imaging, optics, medical applications, water splitting, energy research and environmental remediation.

This study reports the generation of polyvinyl pyrrolidone (PVP)-capped ZnS nanospheres using the solvothermal method with PVP as a surfactant. Field emission scanning electron microscopic examination of the prepared sample verified its nanosphere form. The elemental composition was confirmed using EDX and elemental mapping. The effectiveness of the synthesized material’s ability to bind mercury was examined using a variety of isotherm and kinetic models, and it was found that the Freundlich isotherm model and pseudo-second-order kinetics, respectively, govern the mercury removal adsorption process. The prepared sample eliminated 95.8% of the mercury from the aqueous solution in 6 h. PVP-capped ZnS nanospheres showed the highest adsorption efficacy of 319 mg/g towards the mercury removal process.

Nanogenerators are widely used in harvesting and converting mechanical or thermal energy into electric energy. It is a promising way to capture energy from the surrounding environment as portable power supplies and self-powered systems, offering great versatility and feasibility. Current studies focus on designing nanogenerator structures and materials with high power outputs, multifunctionality and low-cost characteristics. In this review, we will introduce the technological advances of three common nanogenerators, namely, triboelectric, piezoelectric and pyroelectric nanogenerators. The fundamental components, including the working mechanism, structure design, materials selection and main applications, are compared and systematically discussed. Current challenges and future perspectives are highlighted with a focus on offering new insights into developing the next generation nanogenerators that are highly integrated, multifunctional and of upgraded performance.

The mass production of human induced pluripotent stem cells (hiPSCs) is important in the area of regenerative medicine. During proliferation, stem cells metabolize D-glucose into L-lactate, the accumulation of which in a cell culture medium impairs the mass production of cells. It is therefore important to supply D-glucose and remove L-lactate from the cell culture medium to ensure that the stem cell mass culture can be achieved. In the present study, L-lactate-selective Mg-Al layered double hydroxide (LDH) adsorbents containing celL-culture-compatible exchangeable anions were designed. More specifically, different stem cell nutrients (i.e., L-alanyL-L-glutamine, L-glutamine, L-serine, L-methionine, L-cysteine, L-glutamate and α-ketoglutarate) and the cell culture buffer component (i.e., 4-(2-hydroxyethyl)-1-piperazineethanesulfonate (HEPES)) were incorporated into the Mg-Al LDHs via a rehydration method. The orientations of the organic guests and the host–guest interactions were characterized using a range of analytical and computational techniques. It was deduced that the L-lactate adsorption ability of the LDHs and the selectivity over D-glucose depended on a number of factors, including the charge density of the LDH guest relative to L-lactate, the guest orientation and the hydrogen bonds formed in the host–guest, guest–guest and guest–host–glucose complexes. Overall, this study provides insights into the design of effective and potentially biocompatible adsorbents for cell culture media regeneration to promote the cost-effective mass production of stem cells.