Synthesis of bornite Cu5FeS4 nanoparticles via high energy ball milling: Photocatalytic and thermoelectric properties

Incorporation of Cu5FeS4 QDs with Abundant Oxygen Vacancy TiO2 QDs/TiO2 OVs: Double S-Scheme Photocatalysts for Effectual N2 Conversion to NH3 under Simulated Solar Light

Photocatalytic N2 conversion to NH3 is a green, sustainable pathway with renewable energy sources and carbon neutrality. In this research, ternary TiO2 QDs/TiO2 OVs/Cu5FeS4 nanocomposites were prepared by an easy and affordable procedure and utilized to produce clean ammonia energy without a sacrificial agent. The amount of produced green ammonia by the optimum nanocomposite achieved was 17,274 μmol L-1 g-1, which was approximately 20.9, 6.48, 4.45, 2.26, and 1.45 times higher than those of commercial TiO2, TiO2 QDs, TiO2 OVs, Cu5FeS4, and TiO2 QDs/TiO2 OVs photocatalysts, respectively. Lattice compatibility through the developed homojunction within TiO2 QDs/TiO2 OVs and the integration of Cu5FeS4 nanoparticles led to the establishment of a double S-scheme homo/heterojunction system, which improved the photocatalytic activity by maintaining electrons and holes with high oxidation and reduction power and greatly reduced the recombination of charges, which led to the acceleration of charge transfer and migration. Besides, the promoted surface area compared to the pure components, introducing oxygen vacancies, and reducing the particle size boosted the photocatalytic N2 conversion to NH3. The results of this research are a basis for the rational design of homojunction/heterojunction visible-light-responsive systems for photocatalytic nitrogen fixation reactions.

Biogenic synthesis of novel nanomaterials and their applications

Despite the many benefits derived from the unique features and practicality of nanoparticles, the release of their toxic by-products or products from the synthesis stage into the environment could negatively impact natural resources and organisms. The physical and chemical methods for nanoparticle synthesis involve high energy consumption and the use of hazardous chemicals, respectively, going against the principles of green chemistry. Biological methods of synthesis that rely on extracts from a broad range of natural plants, and microorganisms, such as fungi, bacteria, algae, and yeast, have emerged as viable alternatives to the physical and chemical methods. Nanoparticles synthesized through biogenic pathways are particularly useful for biological applications that have high concerns about contamination. Herein, we review the physical and chemical methods of nanoparticle synthesis and present a detailed overview of the biogenic methods used for the synthesis of different nanoparticles. The major points discussed in this study are the following: (1) the fundamentals of the physical and chemical methods of nanoparticle syntheses, (2) the use of different biological precursors (microorganisms and plant extracts) to synthesize gold, silver, selenium, iron, and other metal nanoparticles, and (3) the applications of biogenic nanoparticles in diverse fields of study, including the environment, health, material science, and analytical chemistry.

Peptide-metal nanohybrids (PMN): Promising entities for combating neurological maladies

Nanotherapeutics are gaining traction in the modern scenario because of their unique and distinct properties which separate them from macro materials. Among the nanoparticles, metal NPs (MNPs) have gained importance due to their distinct physicochemical and biological characteristics. Peptides also exhibit several important functions in humans. Different peptides have received approval as pharmaceuticals, and clinical trials have been commenced for several peptides. Peptides are also used as targeting ligands. Considering all the advantages offered by these two entities, the conjugation of MNPs with peptides has emerged as a potential strategy for achieving successful targeting, diagnosis, and therapy of various neurological pathologies.

Recent advances in metal sulfide nanoparticle-added bionanocomposite films for food packaging applications

Metal sulfide nanoparticles have recently attracted much attention due to their unique physical and functional properties. Metal sulfide nanoparticles used as optoelectronic and biomedical materials in the past decades are promising for making functional nanocomposite films due to their low toxicity and strong antibacterial activity. Recently, copper sulfide and zinc sulfide nanomaterials have been used to produce food packaging films for active packaging. Metal sulfide nanoparticles added as nanofillers are attracting attention in packaging applications due to their excellent potential to improve mechanical, barrier properties, and antibacterial activity. This review covers the fabrication process and important applications of metal sulfide nanoparticles. The development of metal sulfides reinforcing mainly copper sulfide and zinc sulfide nanomaterials as multifunctional nanofillers in bio-based films for active packaging applications has been comprehensively reviewed. As the recognition of metal sulfide nanoparticles as a functional filler increases, the development and application potential of active packaging films using them is expected to increase.

Synthesis of nanomaterials using various top-down and bottom-up approaches, influencing factors, advantages, and disadvantages: A review

Nanotechnology is one of the emerging fields of the 21st Century. Many new devices and patentable technology is based on nanomaterials (NMs). One of the dominant factors in the use of nanomaterials and their applications in various fields is the synthesis and growth mechanism of nanostructures and nanomaterials. A nanostructured material may have been a good candidate in one application but could be more useful in a different application if synthesized by a different mechanism and technique. Similarly, the structure and morphology of a nanomaterial also depend upon the method of growth and synthesis. For example, it is easy to grow and synthesize amorphous nanostructured thin film using the plasma magnetron sputtering technique, but it may be difficult to obtain a similar structure using the thermal evaporation process due to the nature of the technique itself. In this study, the Top-down and Bottom-up methods and techniques of synthesizing nanostructured materials are reviewed, compared, and analyzed. Both approaches are critically analyzed, and the influencing factors on the synthesis of different nanomaterials, the advantages, and disadvantages of each technique are reported. This review also provides a step-by-step analysis of the choice of method for the synthesis of namomaterials for specific applications.

Metal Sulfide Nanoparticles: Precursor Chemistry

Fascination with and the need for evermore increasing efficiency, power, or strength have been the cornerstones for developing new materials and methods for their creation. Higher solar cell conversion efficiencies, increased battery storage power, and lightweight strong materials are some that have been at the forefront of attention for these efforts. Materials created for most applications start as simple chemical compounds. A study of how these chemicals have been used in the past can be used to create new materials and new methods of production. Herein, a class of materials that are valuable in a multitude of applications, metal sulfide nanoparticles, are examined, along with how they are being produced and how new methods can be established that will help to standardize and increase production capabilities. Precursor–solvent combinations that can be used to create metal sulfide nanoparticles in the gas phase are also explored.

Low-Toxic, Earth-Abundant Nanostructured Materials for Thermoelectric Applications

This article presents recent research directions in the study of Earth-abundant, cost-effective, and low-toxic advanced nanostructured materials for thermoelectric generator (TEG) applications. This study's critical aspect is to systematically evaluate the development of high-performance nanostructured thermoelectric (TE) materials from sustainable sources, which are expected to have a meaningful and enduring impact in developing a cost-effective TE system. We review both the performance and limitation aspects of these materials at multiple temperatures from experimental and theoretical viewpoints. Recent developments in these materials towards enhancing the dimensionless figure of merit, Seebeck coefficient, reduction of the thermal conductivity, and improvement of electrical conductivity have also been discussed in detail. Finally, the future direction and the prospects of these nanostructured materials have been proposed.

Structural Core-Shell beyond Chemical Homogeneity in Non-Stoichiometric Cu5FeS4 Nano-Icosahedrons: An in Situ Heating TEM Study

Thermal stability of core-shell structured nanoparticles is of vital importance to their practical applications at elevated temperature. Understanding the evolution of chemical distribution and the crystal structure of core-shell nanostructures with temperature variation at the nanoscale will open the route for practical applications and property enhancement of nanoparticles through proper design of new nanomaterials. In this study, core-shell non-stoichiometric Cu₅FeS₄ icosahedral nanoparticles were investigated by in situ heating transmission electron microscopy. Compared to the high structural and compositional stability at room temperature, the interdiffusion of Cu and Fe atoms became significant, ending up with disappearance of chemical difference in the core and shell over 300 °C. In contrast, different crystal structures of the core and shell were preserved even after heating at 350 °C, indicating the high structural stability. The inconsistency between chemical composition and crystal structure should be ascribed to the interaction between the intrinsic strain existing in the icosahedrons and various structures of this material system. In other words, the geometrically intrinsic strain of the nano-icosahedrons is helpful to modulate/maintain the core-shell structure. These findings open new opportunities for revealing the thermal stability of core-shell nanostructures for various applications and are helpful for the controllable design of new core-shell nanostructures.

The puzzling structure of Cu5FeS4 (bornite) at low temperature

The crystal structure of Cu₅FeS₄ (bornite) has been investigated using synchrotron X-ray powder diffraction at temperatures between 10 and 275 K. Diffraction data confirm that bornite crystallizes in the orthorhombic space group Pbca at 275 K. The unit-cell volume decreases continuously on cooling, but undergoes an abrupt contraction below ∼65 K, where a first-order Pbca→Pca2₁ structural transition takes place. The primary active mode yielding the observed ordered structure corresponds to the irreducible representation Γ₂^-, with wavevector (0,0,0). Pair distribution function analysis shows strong discrepancies between the local and the average structure. The average Fe-S bond length obtained through the EXAFS local probe is consistent with the values independently provided by X-ray powder diffraction data, strongly supporting the preferred location of Fe.