Insight into the enhanced CO2 photocatalytic reduction performance over hollow-structured Bi-decorated g-C3N4 nanohybrid under visible-light irradiation
Description
The morphology structure was investigated by scanning electron microscopy (SEM, HITACHI UHR FE-SEM, SU 8010) and transmission electron microscopy (TEM, H-600, Hitachi, Ltd., Japan, Voltage: 200KV). X-ray diffraction (XRD, Model D/max RA, Rigaku Co., Japan with Cu Kα radiation) analysis was performed to analyze the crystal phase of the as-synthesized samples. The surface properties were studied by X-ray photoelectron spectroscopy (XPS) on a Thermal ESCALAB 250 instrument with a monochromatic Al Kα source (150 W, 500 μm, 1486.6eV). The C1s level at 284.8 eV was used as the reference to calibrate the binding energy. The specific area and pore structure were calculated from the N2 adsorption–desorption isotherms by the multipoint Brunauer–Emmett–Teller (BET) method. UV-visible diffuse reflection spectra (UV–vis DRS) were recorded on a UV–vis spectrophotometer (TU-1901, China) equipped with an integrating sphere assembly. Photoluminescence (PL) spectra were acquired on a fluorescence spectrophotometer (FLS920, Edinburgh Instruments, UK) equipped with a xenon lamp at an excitation wavelength of 380 nm. The time-resolved fluorescence was measured using the same analytical instrument excited at 380 nm and monitored at 405 nm. Photoelectrochemical characterizations were performed on an electrochemical system (CHI-660B, China) in a three-electrode cell made of quartz containing a 0.2M Na2SO4 electrolyte solution. Platinum wire (CHI115) was used as the counter electrode, saturated Ag/AgCl (CHI111) as the reference electrode. The working electrode was prepared with a piece of ITO glass, in the middle of which, an area of 1×1 cm2 was coated with our samples with the help of a coating solution. Electrochemical impedance spectroscopy (EIS) measurements were carried out at 0.0 V on a 12608 W electrochemical system (Solartron Mobrey, England), with a sinusoidal ac perturbation of 5 mV applied to the electrode over the frequency range of 100 –1.8 M Hz. In-situ DRIFT spectra were recorded on a Tensor 27 spectrometer (Thermo Nicolet Corporation, USA) with a Harrick low-temperature chamber.