*2.5. Preparation of TiO2/rGO/Ag Hybrid Nanostructure by In Situ Growth*

The TiO2/rGO/Ag hybrid nanostructures were synthesized by an in situ hydrothermal process. In this procedure, 10 mg of silver nitrate was dissolved in 60 mL of DI water (30 mL) and ethanol (30 mL), and then 0.2 g of the prepared TiO2/rGO was added to the above solution under continuous stirring for 1 h. The net solution was transferred into an autoclave and kept at 180 ◦C for 4 h. The final product was washed with DI water and dried at 60 ◦C.

#### *2.6. Characterization*

Structural analysis was conducted using X-ray diffraction (XRD; PANalytical, Malvern, UK) with Cu Kα radiation (λ = 1.5406 Å) in the 2-theta range between 10◦ and 80◦ with a scanning rate of 0.02◦/min. Raman spectra of the prepared sample were obtained using a micro-Raman spectrometer (LABRAM HR Evolution, Horiba, Longjumeau, France) with an excitation wavelength of 532 nm. The surface morphology of the prepared samples was analyzed using high-resolution scanning electron microscopy (HR-SEM; Apreo S, Thermo Fisher Scientific, Hillsboro, OR, USA) with an acceleration voltage of 15 kV. Further analysis of the surface morphology was conducted using high-resolution transmission electron microscopy (HR-TEM; JEM-2100, JEOL, Tokyo, Japan) with an acceleration voltage of 200 kV to reveal the atomic interplanar morphology and the elemental composition of the prepared samples. Ultraviolet-visible diffuse reflectance spectroscopy (UV-DRS, V-750, JASCO, Tokyo, Japan) measurements were conducted in the range of 200 nm to 800 nm. To analyze the emission properties of the prepared sample, photoluminescence (PL; FP8600, JASCO, Tokyo, Japan) spectra were measured at room temperature. The surface area and pore size distribution of the samples were characterized by the BET (Brunauer–Emmett–Teller) and BJH (Barrett–Joner–Halenda) methods (Autosorb IQ series, Quantachrome Instruments, Boynton Beach, FL, USA). X-ray photoelectron spectroscopy (XPS) was performed via a Kratos analytical instrument (ESCA 3400, Shimadzu Corporation, Kyoto, Japan). The percentage of mineralization efficiency was determined from total organic carbon (TOC) measurements (TOC-L, Shimadzu, Kyoto, Japan). Photovoltaic characterization of the fabricated devices was performed using a solar simulator (Sciencetech, Class A, Lamp: 300 W, London, ON, Canada). The I-V measurement and incident photocurrent efficiency (IPCE) of fabricated devices was measured using the same solar simulator over the wavelength range of 200 nm to 800 nm.
