Jsm 6710f

The chemical compositions of the catalysts were characterized using SAED (SAED, TEM mode, JEOL 3010, 300 kV, 112 μA) and Raman spectroscopy (Modular System, Horiba Jobin Yvon). A He–Ne laser was used as the excitation source and the acquisition time was 10 seconds for each spectrum. A dry objective (Olympus MPlan N, 50×, numerical aperture = 0.75) and a water immersion objective (Olympus LUMFL, 60×, numerical aperture = 1.10) were, respectively, employed for ex situ and operando Raman spectroscopy. The morphologies of the catalysts were characterized by SEM (JEOL JSM-6710F, 5 kV). Their electrochemical-active surface areas were determined by their double layer capacitances in N₂-saturated 0.1 M KClO₄ (99.9%, Sigma Aldrich). A three-electrode setup was used with a Pt wire counter and a Ag/AgCl reference electrode (Saturated KCl, Pine). Cyclic voltammetry were performed in a non-faradaic region from −0.05 V to 0.05 V vs. RHE. The scan rates were 50, 100, 150, 200, 250, 300, 350, and 400 mV s⁻¹.

Structural and morphological characterization of as-synthesized CuO NPs were analyzed by various analytical techniques. The absorption spectra were recorded by an UV−visible Spectrophotometer (Thermo Scientific GENESYS 10S). The recombination of electron-hole pairs of the synthesized samples was investigated using photoluminance spectroscopy (Perkin Elmer LS 55 Fluorescence Spectrometer, Waltham, MA, USA) with excitation wavelength at 350 nm in the range 350–600 nm. FTIR studies were carried out at room temperature in the range of 400−4000 cm⁻¹ with resolution of 4 cm⁻¹ by using KBr pellets in a Perkin Elmer RX1 spectrophotometer. The X-ray powder diffraction patterns were taken in reflection mode with Cu Kα (λ = 1.5406 Å) radiation in the 2θ range from 10° to 80° by using a Shimadzu XRD 6000 (Kyoto, Japan) X-ray diffractometer by continuous scanning which was operated at 40 kV/30 mA and 0.02 min⁻¹. The X-ray photoelectron spectra was obtained using Perkin Elmer PHI5600 (ULVAC-PHI, Inc, Waltham, MA, USA). A FESEM [JEOL JSM-6710F, Kyoto, Japan combined with energy dispersive X-ray analyzer (X-max, 150 Oxford Instruments)] and HRTEM (JEOL JEM-3010) were used for morphological, microstructural and elemental compositional analysis of synthesized CuO NPs.

The selection of optimized parameters in green synthesizing ZnO-CuO NCs was based on their structural, morphological and optical properties. The absorption spectra were recorded by a UV-Visible (UV-Vis) spectrophotometer (Thermo Scientific GENESYS 10S, Waltham, MA, USA). The recombination of electron-hole pairs (e⁻/h⁺) of the synthesized samples was investigated using photo luminance (PL) spectroscopy (Perkin Elmer LS 55 Fluorescence Spectrometer, Waltham, MA, USA) with an excitation wavelength of 350 nm in the range of 350 to 600 nm. The Fourier Transform Infrared (FTIR) spectroscopy study was carried out at room temperature in the range of 4000 to 400 cm⁻¹ with a resolution of 4 cm⁻¹ by using KBr pellets in a Perkin Elmer RX1 spectrophotometer. X-ray powder diffraction (XRD) patterns were taken in the reflection mode with Cu Kα (λ = 1.5406 Å) radiation in the 2θ range of 10° to 80° by using a Shimadzu XRD 6000 X-ray diffractometer with continuous scanning which was operated at 40 kV/30 mA and 0.02 min⁻¹. The morphological, microstructural and elemental compositional of all synthesized samples was determined using a Field Emission Scanning Electron Microscope (FE-SEM) (JEOL JSM-6710F, Tokyo, Japan) with Energy Dispersive X-ray (EDX) analyzer (X-max, 150 Oxford Instruments, Abingdon-on-Thames, UK).

The morphology of the prepared sol-gel-coated AAO membrane was investigated by SEM (JSM-6710F, JEOL, Tokyo, Japan). After post-gelation, the samples were dried overnight in a vacuum chamber to eliminate water from the sol-gel matrix and thereafter transferred to the carbon tape on the SEM specimen stub. Subsequently, the prepared samples were coated with platinum to reduce the charging effects during SEM analysis. The structure of sol-gel nanocolumn defined by the AAO membrane was also observed by TEM (H-7650, Hitachi, Japan) after dissolving the AAO template using a 1 M NaOH solution for 3 h at 30 °C. The white precipitate upon completing the AAO dissolution reaction in the sample tube was collected by mild centrifugation with a washing step using filtered distilled water. Finally, the acquired sol-gel nanocolumn was dispersed by mild pipetting and drop-casted onto a carbon 200 mesh copper grid (Ted Pella, Redding, CA, USA). The prepared samples were dried overnight in a vacuum desiccator and observed by TEM under optimized conditions.