Abstract:

Polymeric carbon nitride（CN） has been widely studied and applied in the field of photocatalysis benefiting from its visible light response，high chemical stability，low cost，easy preparation and non-toxicity.However，its shortcomings，such as small specific surface area and easy recombination of electron-hole pairs，seriously limit its photocatalytic performance.Co doped CN was prepared by one-step calcination of urea and two widely used cobalt salts[CoCl₂ and Co（NO₃）₂] as precursors，and the effects of different Co sources on the photocatalytic CO₂ reduction performance of the products were studied.The results showed that the photocatalytic CO₂ reduction performance of CN doped with appropriate amount of Co by using CoCl₂ as Co source was improved.The CO generation rate was increased from 82.7 μmol/（g·h）for pure CN to 374.5 μmol/（g·h），and the CO selectivity was increased from 79.1% to 88.5%.By contrast，Co doped CN using Co（NO₃）₂ as Co source was tended to produce hydrogen，and its photocatalytic CO₂ reduction performance was not improved.The photocatalysts were characterized by inductively coupled plasma（ICP），X-ray diffraction（XRD），fourier infrared spectroscopy（FT-IR），X-ray photoelectron spectroscopy（XPS），UV-Vis diffusion reflection spectroscopy（UV-Vis DRS），scanning electron microscopy（SEM），physical adsorption，photoelectrochemical test and etc.，and the material structure and the reasons for the improvement of the photocatalytic performance were analyzed.

Key words: polymeric carbon nitride, metal doping, photocatalysis, carbon dioxide reduction