Herein, spectrally selective single-layered CuO nanocoatings were successfully demonstrated via green synthesis and deposited on stainless steel (SS) substrates using a spin coater at 700, 800, 900, and 1000 rpm. The morphological, structural, and compositional analyses of the obtained nanocoatings were studied using SEM, XRD, EDX, and Raman spectroscopy. The SEM images show nanorod-like structure surfaces with dense surface morphology. The XRD patterns confirmed the presence of peaks indexed to a monoclinic structural phase of CuO. The EDX spectra clearly revealed the presence of Cu and O elements, and XPS spectra showed peaks of Cu2p and O1s core levels, which are typical characteristics of Cu (II) and O(II), respectively, in CuO. The Raman spectra showed peaks at 305, 344, and 642 cm⁻¹ attributed to Raman active (A_g+2B_g) modes for Cu-O stretching. Rutherford backscattering spectrometry (RBS) determined the content of the elements and the changes in the thicknesses of the coatings with the rotational speed (RS) of the spin coater. The elemental content of Cu and O atoms were, respectively, 54 and 46%. The thicknesses were calculated to be 1.406 × 10¹⁸ atoms/cm² (296.3 nm), 1.286 × 10¹⁸ atoms/cm² (271.0 nm), 1.138 × 10¹⁸ atoms/cm² (239.8 nm), and 0.985 × 10¹⁵ atoms/cm² (207.5 nm) at 700, 800, 900 and 1000 rpm, respectively. The optical properties of the CuO nanocoatings were characterized using UV–Vis–NIR and FTIR spectrometers; its vital solar selectivity parameters of solar absorptance (α) and emissivity (ε) were evaluated in the ranges of 0.3–2.5 and 2.5–20 µm wavelengths, respectively. The obtained coatings exhibited solar parameters (α = 0.90, and ε = 0.31) associated with 700 rpm due to an intrinsic and interference-induced absorption as well as higher attenuation of light.

The aim of this work was to study structural and kinetic parameters as well as the mechanism of platinum nanoparticles (PtNP) reduced with sodium borohydride (NaBH4) and capped with polyvinyl pyrrolidone (PVP). The nanoparticles were supported on Pt electrode for ammonia oxidation in fuel cell application. X-ray diffraction (XRD) was used to study structural composition and high resolution transmission electron microscopy (HRTEM) was used for morphological study of the nanoalloy. The electrocatalysts were studied in alkaline solution of potassium hydroxide (KOH) by cyclic voltammetry (CV), square wave voltammetry (SWV) and electrochemical impedance spectroscopy (EIS). CV showed that the ammonia oxidation over potential for PtNP was -431 mV and with exchange current density of 1.726 × 10^-4 A. EIS showed that the charge transfer resistance (R_ct) of PtNP was the lowest (R_ct = 1.943 × 10⁶ Ω) compared to that of bare Pt working electrode (2.0604 × 10⁶ Ω), indicating that the Pt nanoparticles have good conductivity and played an important role in accelerating the transfer of electrons.