Characterizations

The molar ratios of the samples were determined by Atomic Absorption Spectrometer (AAS Various 6, Analytik Jena AG, German). X-ray diffraction (XRD) patterns were collected on a MiniFlex600 desktop X-ray diffractometer operated at 30 kV and 10 mA using Cu Kα irradiation (Wavelength = 1.5406 Å). Scanning electron microscopy (SEM) images were recorded on a S-4800 scanning electron microscope at an accelerating voltage of 200 kV. Fourier transform infrared (FTIR) spectra were recorded on a Brook Tensor 27 Fourier transform infrared spectrometer) using the KBr pellet technique. UV-vis diffuse reflectance spectra were recorded on a Perkin Elmer Lambda 950 ultraviolet spectrophotometer. N₂ adsorption-desorption isotherms were conducted at 77 K using an Accelerated Surface Area and Porosimetry Analyzer (ASAP2010, Micromeritics) after degassing the samples at 100 °C for 4 h. The specific surface areas were determined by the Brunauer-Emmett-Teller (BET) methods. The CO₂ adsorption capacity was calculated from the weights of the samples before and after CO₂ adsorption in a home-made quartz fixed bed reactor (Fig. 8).

Schematic of the apparatus for CO₂ adsorption and photocatalytic CO₂ reduction.