K alpha type

The normal and popular characterization procedures were adopted to identify the synthesized nanoparticles as follows: X-ray diffraction (XRD) analysis that applied to detect the crystalline phase (using Bruker axis D8 with Cu Kα radiation instrument at RT). Nanostructure and surface morphologies were checked out applying JEOL-JEM-1230 transmission electron microscopy (TEM). To perform this measurement, the specimens were suspended in ethanol and subjected to ultrasonicator for nearly 30 min, after that; a tiny dose of the suspended and sonicated solution was left to dry on a copper grid coated with carbon and loaded into the TEM instrument. A Thermo Scientific spectrometer (K-ALPHA-type) was adopted to perform the X-ray photoelectron spectroscopy (XPS) measurements. Surface characterization was accomplished applying Nitrogen-adsorption assessments on the specimens with a Chromatech instrument (Nova 2000 series). On the other hand, a fluorescence spectrophotometer (Shimadzu RF-5301) was adopted to display the Photoluminescence emission spectra (PL). Whereas, UV-Vis-NIR spectrophotometer (V-570, Jasco, Japan) was supported in order to estimate the band gap performance from the UV-Vis diffuse reflectance spectra (UV-Vis-DRS); the experiment was performed in normal condition (air) at ambient temperature to identify absorption from 200 up to 800 nm.

The characterization of the catalyst mainly included crystal structure, microscopic morphology, element composition, and pore size distribution. The X-ray diffractometer model DX-2700 (Dandong Fangyuan Instrument Co. LTD, Dandong, China) was used for testing. The X-ray tube was copper palladium (λ = 1.5417 Å), the scanning step width was 0.02°, and the scanning angle was 10°~80°. The tube voltage and tube current were set to 40 kV and 30 mA, respectively. A scanning electron microscope (SEM, Zeiss SIGMA 300 field-emission, Oberkochen, Germany) characterized the microscopic morphology of the catalyst. Transmission electron microscopy (TEM) (FEI Tecnai G2 F20, FEI, Eindhoven, The Netherlands) collected information at a voltage of 200 kV. An inductively coupled plasma optical emission spectrometer (ICP-OES) measurement was performed with Agilent 720ES (Santa Clara, CA, USA), and the actual proportion of iron in the catalyst with different iron precursor content was determined. The K-Alpha type of Thermo Scientific (Waltham, MA, USA) was used to test the catalyst to obtain the valence state and surface energy state distribution of the catalyst by analyzing the X-ray photoelectron spectroscopy (XPS) (Thermo Scientific, Waltham, MA, USA).