Ihr550 imaging spectrometer

Transmission electron microscopic (TEM) images were taken with a H-7000 instrument (Hitachi, Tokyo, Japan) at an accelerating voltage of 100 kV. The dispersion of AuNPs was dropped on a carbon-coated copper grid, air-dried, and then used for the observation. Ultraviolet-visible-near infrared (UV-vis-NIR) absorption spectra were recorded with a V-670 spectrophotometer (JASCO, Tokyo, Japan) with quartz cells of 1 and 10 mm light path for the dispersion. Raman scattering was measured with an iHR550 imaging spectrometer (1800 gr/mm grating and slit opening of 300 μm) from Horiba Jobin Yvon (Kyoto, Japan) equipped with a confocal microscope (object lens: MPlan N 50X, Olympus, Tokyo, Japan, working distance of 0.38 mm).

Investigation of crystalline nature of as synthesized materials was done using D8 Bruker X-ray Diffractometer varying the incident angle from 20° to 80° using Cu-Kα radiation (λ = 1.5418 nm). XPS measurements were performed in ultra-high vacuum conditions using standard Omicron system equipped with monochromatic Al Kα 1486.7 eV X-ray source operated at 15 KeV at constant analyzer energy of 100 eV for survey scans and 20 eV for detailed scans. Morphology of fabricated photocatalysts was examined by scanning electron microscope (Hitachi S-4800 microscope operated at 20 kV) and JEOL-2100 TEM. The SEM was fitted with EDAX for elemental mapping of the synthesized materials. Raman spectroscopy was performed with a home-made confocal setup fitted with a 532 nm laser. The measurements were performed at 1 mW of excitation power and spectra recorded using an iHR550 imaging spectrometer (from Horiba Scientific). Surface area was calculated through nitrogen physisorption with Nova 2200e (Quantachrome). Diffuse reflectance was recorded in the wavelength ranging from 200 to 800 nm with PerkinElmer, Lambda 750 UV–Vis–NIR spectrophotometer, equipped with integrating sphere. Energy band gap of synthesized photocatalysts were calculated by Kubelka-Munk equation. Room Temperature PL spectra were measured with RF-5301 PC Fluorescence Spectrofluorophotometer (Shimadzu, Japan).