Journal of Nano Research Vol. 79

Abstract: Photocatalytic CO₂ reduction to solar fuel is a potential way to overcome the problem of high carbon dioxide concentrations; however, the process still faces enormous challenges, such as the low light absorption efficiency and high carrier recombination rates. This work synthesized tetraphenylporphyrin-based carbon dots (TPP-CDs) for the photocatalytic CO₂ reduction to CH₃OH under simulated sunlight to extend the absorption region of the CDs. The conduction band of the TPP-CDs has a sufficiently negative reduction potential to reduce CO₂. TPP-CDs containing 1 wt.% TPP achieved an optimum CH₃OH production rate of 173.35 μmol·g_cat^-1·h^-1, with a remarkable 2.06-fold increase compared to pristine CDs without TPP. In this study, TPP-CDs were synthesized by changing the CD precursors to improve the utilization of visible light and apply them to the photocatalytic reduction of CO₂.

Abstract: Using a facile hydrothermal method, ZnO nanomaterials with various morphological structures (nanowires, nanodiscs, and nanostars) were produced. An investigation was conducted into the relationships between the exposed polar facets and the photocatalytic activities. Based on XPS, Pl, and structural analysis, it was discovered that the exposed facets’ chemsorption ability of the different ZnO nanomaterials with different morphologies plays a vital role in their photocatalytic properties. Zinc-terminated surfaces had the highest chemsorption ability and consequently the ZnO nanodiscs with the highest fraction of exposed Zinc-terminated facets were the ideal photocatalysts from the tested morphologies. This work emphasises the important influence of rational control over the nanomaterial morphology on its physical and chemical properties and therefore on its performance in various practical applications.

Abstract: Industrial dyes contained a wide range of organic compounds that could affect the environment and high dimensional challenges to humans. In recent years, the environmentally safe and inexpensive quaternary copper-based chalcogenide Cu₂ZnSnS₄ (CZTS) has emerged as a material for photovoltaics and photocatalysis. CZTS nanoparticles were prepared in this investigation using the hydrothermal route at 210 °C for 24 h without the addition of a surfactant or capping agents. Rhodamine B (RhB), a carcinogenic dye, was degraded using the synthesized material through a photocatalytic process. The structural, morphological, optical, and photocatalytic characteristics of CZTS nanoparticles were examined using X-ray diffraction (XRD), Raman spectroscopy, Field emission scanning electron microscopy (FE-SEM), and UV-vis spectroscopy. The average particle size of CZTS is found to be 31 nm with crystalline nature have been characterized by XRD. The results demonstrate that the synthesized sample has mixed morphological structures such as clew-like and flower-like structures and a bandgap of 1.50 eV. CZTS nanoparticles were used as photocatalysts under direct sunlight for Rhodamine B degradation, with the fastest degradation efficiency of 72% at 50 minutes. The results show that surfactant-free hydrothermally synthesized CZTS nanoparticles are a very promising material for the degradation of RhB dye due to the rapid degradation rate and high degradation efficiency.

Abstract: The article presents the investigation of the effect of the modulation period of the nanomultilayer CrN/TiN coatings, deposited by arc-PVD technology, on the coatings' mechanical and tribological properties. The studied modulation period was in the range from 6 to 16.5 nm. The measured coatings hardness was in the range of 26 - 29 GPa, and the plasticity index was 0.07. The tribological properties were measured against Al₂O₃ and ZrO₂ counterparts. The lowest value of wear rate was measured at the CrN/TiN nanomultilayer costing with modulation period of 8.4 nm.

Abstract: Mesoporous silica nanoparticles were synthesized via sol–gel method to produce uniform size nanoparticles using n-Octadecyl-trimethoxy silane which gives a good dispersion of silica nanoparticles in hydrophobic mediums. Scanning electron microscopy (SEM), infrared spectroscopy, X-ray diffraction (XRD), thermal gravimetric analysis, and nitrogen adsorption-desorption tests were used to thoroughly investigate the nanocomposites' morphology and structure. BET results show a high surface are of 760 m²/g and specific high pore size (30Ȧ) and pore volume (0.336 cm³/g). The SEM results present that the mesoporous silica nanoparticles possess a well dispersed and uniform particle morphology and FTIR interpenetrating the well-prepared silica nanoparticles which possess Si-O-Si and Si-O bond. The XRD analysis confirmed the amorphous nature silica nanoparticles. The electrochemical properties of silica nanoparticles were evaluated in a potassium chloride solution. With the advantages of a large specific surface area and a suitable pore size distribution, a pair of broad and symmetric redox peaks centred at -0.15 V and 0.6 V appears. Mesoporous silica with a large effective specific surface area demonstrated excellent electrochemical performance, making them excellent candidates for supercapacitors and fuel cells.

Abstract: Raw pumice samples were modified with nano carbon black, borax, and nano carbon-borax using the sol-gel method by applying surface modification processes, and the changes in the thermal behavior of the surface modification of the raw pumice were studied by characterizing them with FE-SEM, EDX, FT-IR, XRD, BET and TGA-DTA. In the analyses made with FE-SEM, it was observed that the surface and pore structure of the raw pumice changed after the modified process, and in the EDX analysis, it was determined that nano carbon black and borax adhered to the surface of the raw pumice. In the XRD results, no change in the crystal structure of the raw pumice was observed after the modified treatment. TGA-DTA analysis showed that the mass loss of raw pumice (P) was greater than pumice-nano carbon black (PC), pumice-borax (PB), and pumice-borax-nano carbon black (PBC). Accordingly, raw pumice showed a mass loss of approximately 25%, pumice-borax (PB) and pumice-nano carbon black (PC) 0.45%, and pumice-borax-nano carbon black (PBC) nearly 3%. According to the BET analysis results, it was determined that the raw pumice has a surface area of 28.126 m²/g. After the surface modification process, the surface area of the raw pumice was determined as 52.127 m²/g in the pumice-nano carbon black sample, 49.125 m²/g in the pumice-borax sample, and 32.523 m²/g in the pumice-borax-carbon black sample. Considering the data obtained, the best surface properties were showed in pumice-nano carbon black (PC). Research results showed that; the modification process with nano carbon black and borax changed the thermal behavior of raw pumice.

Abstract: The bending response of two-dimensional (2D) functionally graded (FG) nonlocal strain gradient nanobeams is explored analytically in this work. The longitudinal and transverse orientations vary in material gradation and material characteristics. Kinematic relations of nanobeams are proposed according to hybrid hyperbolic-parabolic functions. The virtual work principle obtains the equilibrium equations, which are then solved using Navier's method. The accuracy and dependability of the suggested analytical model are demonstrated by comparing the results to predictions made in the literature. A thorough parametric study also determines how sensitive the material distribution, the nonlocal length-scale parameter, the strain gradient microstructure-scale parameter, and the geometry are to how the bending response and stresses of 2D FG nanobeams. The results obtained provide benchmark results, which can be used in the design of composite structures.