Springer Science and Business Media LLC

Knowledge, technology, and society as well as natural systems are increasingly coherent and complex, and new systems are continuously formed at their interfaces. Convergence is a problem-solving strategy to holistically understand, create, and transform a system for reaching a common goal, such as advancing an emerging technology in society. The systems may be either in natural, scientific, technological, economic, or societal settings. Convergence offers a unifying strategy applicable to all systems that can be modeled as evolving neural-like networks. The paper presents an overview of the convergence science including underlying theories, principles, and methods and illustrates its implementation in key areas of application. The convergence approach begins with deep integration of previously separated fields, communities, and modes of thinking, to form and improve a new system, from where solutions divergence to previously unattainable applications and outcomes. The worldwide science and technology (S&T) landscape is changing at the beginning of the twenty-first century because of convergence. First, there is the affirmation of three transdisciplinary general-purpose technologies—nanotechnology, digital technology, and artificial intelligence (AI). A second main characteristics is the deep integration of five foundational science and technology fields (NBICA: nanoscale, modern biology, information, cognition, and artificial intelligence) from their basic elements—atoms, genes, bits, neurons, and logic steps and their collective action—to address global challenges and opportunities. The affirmation of nanotechnology at the confluence of disciplines toward systematic control of matter at the nanoscale has been an enabling inspiration and foundation for other S&T fields, emerging industries, and convergence solutions in society. Several future opportunities for implementation of convergence principles are the global S&T system, realizing sustainable society, advancing human capabilities, and conflict resolution.

Engineered iron oxide (Fe3O4) nanoparticles (NPs) were synthesized with a silica shell using a modified alkylsilane approach with o-xylene, as a hydrocarbon media, and transmission electron microscopy (TEM) and single-particle inductively coupled plasma mass spectrometry (spICP-MS) were used to determine the particle size of the Fe3O4 core diameter. In contrast, mass concentrations of the Fe3O4 particles were determined using spICP-MS, using helium (He) as a collision gas to control spectral interferences from ArO and CaO on Fe at m/z 56. Different cell gas flow rates (3, 3.5, and 4 mL/min) and NP’s solution dilution factors from 1:20,000 up to 1:60,000 were investigated; He flow rate of 4 mL/min and a dilution factor of 1:20,000 were found as optimum. The spICP-MS method was calibrated by using gold nanospheres (polystyrene-coated) in toluene as reference material. For the engineered Fe3O4 nanoparticles, TEM. Results gave a (63 ± 6 nm) value for the Fe2O3 core diameter, while spICP-MS was 61.1 ± 4.5 nm (n = 36), demonstrating the excellent agreement among methods. The method was applied for the analysis Fe oxide NPs in petroluem hydrocarbon materials and data compared with TEM. Two standard reference materials (SRMs); NIST 2717a sulfur in residual fuel oil and NIST 8505 vanadium in crude oil were selected. spICP-MS results agreed pretty well among these techniques. These findings suggest that spICP-MS could be useful to characterize Fe-containing particles in complex solution media, such as petroleum hydrocarbons. Graphical abstract

Advances in nanoscale science and engineering suggest that many of the current problems involving the sustainable utilization and supply of critical materials in clean and renewable energy technologies could be addressed using (i) nanostructured materials with enhanced electronic, optical, magnetic and catalytic properties and (ii) nanotechnology-based separation materials and systems that can recover critical materials from non-traditional sources including mine tailings, industrial wastewater and electronic wastes with minimum environmental impact. This article discusses the utilization of nanotechnology to improve or achieve materials sustainability for energy generation, conversion and storage. We highlight recent advances and discuss opportunities of utilizing nanotechnology to address materials sustainability for clean and renewable energy technologies.

Electrical double-layer capacitors (EDLCs) using a biomass-derived activated carbon electrode with Na2SO4–NaI–KI as a redox additive electrolyte were investigated. Biomass-derived activated carbon materials from pomelo peels were prepared by chemical activation in potassium hydroxide followed by carbonization. The biomass-derived activated carbon has a high specific surface area of 1360 m2 g−1, which is suitable for electrode materials. Moreover, a stable couple inorganic redox additive electrolyte were studied by the addition of NaI and KI to Na2SO4 forming a redox additive electrolyte. The electrical double-layer based on activated carbon/Na2SO4–NaI–KI/activated carbon has an excellent specific capacitance (334.3 F g−1), which is 412% higher in comparison with that of activated carbon/Na2SO4/activated carbon (81.14 F g−1) at the same current density of 0.5 A g−1. The EDLC using Na2SO4–NaI–KI electrolyte has a high energy density of 22.75 W h kg−1, which is approximately four times higher than EDLCs based on Na2SO4 (5.52 W h kg−1).

Nanostructured porous films of carbon with density of about 0.5 g/cm3 and 200 nm thickness were deposited at room temperature by supersonic cluster beam deposition (SCBD) from carbon clusters formed in the gas phase. Carbon film surface topography, determined by atomic force microscopy, reveals a surface roughness of 16 nm and a granular morphology arising from the low kinetic energy ballistic deposition regime. The material is characterized by a highly disordered carbon structure with predominant sp2 hybridization as evidenced by Raman spectroscopy. The interface properties of nanostructured carbon electrodes were investigated by cyclic voltammetry and electrochemical impedance spectroscopy employing KOH 1 M solution as aqueous electrolyte. An increase of the double layer capacitance is observed when the electrodes are heat treated in air or when a nanostructured nickel layer deposited by SCBD on top of a sputter deposited film of the same metal is employed as a current collector instead of a plain metallic film. This enhancement is consistent with an improved charge injection in the active material and is ascribed to the modification of the electrical contact at the interface between the carbon and the metal current collector. Specific capacitance values up to 120 F/g have been measured for the electrodes with nanostructured metal/carbon interface.

Terbium fluoride nanocrystals, covered by a shell, composed of cerium fluoride were synthesized by a co-precipitation method. Their complex structure was formed spontaneously during the synthesis. The surface of these core/shell nanocrystals was additionally modified by silica. The properties of TbF3@CeF3 and TbF3@CeF3@SiO2 nanocrystals, formed in this way, were investigated. Spectroscopic studies showed that the differences between these two groups of products resulted from the presence of the SiO2 shell. X-ray diffraction patterns confirmed the trigonal crystal structure of TbF3@CeF3 nanocrystals. High resolution transmission electron microscopy in connection with energy-dispersive X-ray spectroscopy showed a complex structure of the formed nanocrystals. Crystallized as small discs, ‘the products’, with an average diameter around 10 nm, showed an increase in the concentration of Tb3+ ions from surface to the core of nanocrystals. In addition to photo-physical analyses, cytotoxicity studies were performed on HSkMEC (Human Skin Microvascular Endothelial Cells) and B16F0 mouse melanoma cancer cells. The cytotoxicity of the nanomaterials was neutral for the investigated cells with no toxic or antiproliferative effect in the cell cultures, either for normal or for cancer cells. This fact makes the obtained nanocrystals good candidates for biological applications and further modifications of the SiO2 shell. .

Atomic force microscopy (AFM) is typically used to measure the quantum dot shape and density formed by lattice mismatched epitaxial growth such as InAs on GaAs. However, AFM images are distorted when two dots are situated in juxtaposition with a distance less than the AFM tip width. Scanning electron Microscope (SEM) is much better in distinguishing the dot density but not the dot height. Through these measurements of the growth of InxGa1-xAs cap layer on InAs quantum dots, it was observed that the InGaAs layer neither covered the InAs quantum dots and wetting layer uniformly nor 100% phase separates into InAs and GaAs grown on InAs quantum dots and wetting layer, respectively.

Snowflake-like structural assembly of isotropic gold nanoparticles (GNPs) is reported. A modified polyamine method has been employed to synthesize positively charged GNPs in presence of a polymeric metaphosphate. This process yields fascinating dendritic self-assembled morphologies. Structural characterization revealed that there was aggregation of crystalline GNPs. The aggregates of GNPs formed in the initial stage of synthesis are assumed to act as the bulging seeds for final growth of complex morphologies at nanometer to micrometer length scale. Self-assembly of GNPs was found to be greatly influenced by the concentration of gold precursor. Diffusion limited aggregation of GNPs is suggested as the plausible mechanism for this nanoparticle self-organization process.

The transitions of metastable tetragonal phase as well as high-temperature tetragonal phase into the low-temperature monoclinic phase upon heating and cooling were thoroughly studied in zirconia nanoparticles. High-temperature X-ray diffraction, thermal analysis and Raman spectroscopy were used to provide the systematic approach to the investigation of zirconia nanoparticles thermal behavior. A phase transformation sequence in the ZrO2–H2O system was determined, and the mechanisms of tetragonal-to-monoclinic transition upon heating and cooling were suggested. Here, the phenomenon was found and described, which was determined as “self-powdering” of nanoparticles occurring during structural transition. This phenomenon was observed by in situ investigation of the evolution of crystalline nanoparticles from amorphous zirconium hydroxide during thermal treatment in air. The tetragonal-to-monoclinic phase transition, induced by cooling from the temperature of equilibrium of tetragonal zirconia (i.e., above 1170 °C), is accompanied by a significant crystallite size decrease (with corresponding 3–4 times decrease of crystallite volume). The experimental results facilitate applications of zirconia nanoparticles to obtain high-performance nanopowders for nanoceramics.