*4.3. Characterization of the Materials*

The crystalline structure of the catalysts was measured by powder X-ray diffraction XRD (D8 Advance system, Bruker, Billerica, MA, USA), using a Cu Kα radiation source with a wavelength of λ = 0.154178 Å over a 2θ range from 20◦ to 100◦, with a 0.011◦ step width. The morphology of the prepared materials was determined using a scanning electron microscope (SEM), employing a JEOL JSM-6700F field emission instrument (Tokyo, Japan) with a resolution of 100 nm and 1 μm using an EDXS detector. Measurements of X-ray photoelectron spectra were carried out using a Leybold Heraeus (Cologne, Germany) with X-ray source, Mg & Al anode, nonmonochromatic, hemispherical analyzer, 100 mm radius. Data analysis was performed using XPSPEAK 4.1 software (Hong Kong, China). The energy of the C1s-line was set to 284.8 eV and used as reference for the data correction. Diffuse reflectance UV–Vis spectroscopy was employed using a spectrophotometer (Varian Spectrophotometer Cary-100 Bio, Agilent technologies, Santa Clara, CA, USA) at room temperature. Barium sulfate was used as a standard for 100% reflection. The specific surface area (SSA) of the samples was calculated by N2 adsorption–desorption measurements, employing the Brunauer-Emmet-Teller (BET) method using a FlowSorb II 2300 apparatus from Micromeritics Instrument Company (Corp., Norcross, GA, USA). Prior to these measurements, the samples were evacuated at 180 ◦C for 1 h. Measurements of photocurrents and flat band potentials were performed with an electrochemical analyzer using three electrodes employing an Iviumstat potentiostat (Ivium Technologies bv, Eindhoven, The Netherlands). Films of the samples were used as the working electrode, after being coated on cleaned fluorine doped tin oxide (FTO) coated glass using the doctor blade method and calcinated at 400 ◦C for 2 h. These working electrodes were prepared by grinding 100 mg of the photocatalysts and 50 mg polyethylene glycol with one drop of Triton, followed by addition of 200 μL of deionized water and a sufficient amount of ethanol. An Ag/AgCl electrode (3 M NaCl, +209 mV vs. NHE) and a platinum coil were used as the reference electrode and the counter electrode, respectively. Potassium nitrate aqueous solution (0.1 M) was used as the electrolyte. The impedance spectra were recorded in the range between the chosen potential from −1 V to +1 V at frequencies of 10, 100, and 1000 Hz with 20 mV amplitude vs. Ag/AgCl. The capacitance was plotted against V, and the flat band was calculated from the intercept of the plot. (i.e., a plot of C−<sup>2</sup> vs. V, where C was the capacitance and V was the potential across the space charge layer).

### *4.4. Photocatalytic Measurements*
