Photocatalytic reduction of CO2 using Pt doped C3N4 photocatalyts
K. Kočía*, H. V. Dangb, M. Edelmannováa, M. Relia, J. C.S. Wub,
aInstitute for Environmental Technology, VŠB-Technical University of Ostrava, 17. listopadu 15, Ostrava-Poruba, Czech Republic
bDepartment of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan
C3N4 is an abundant carbon based, conjugated polymer with attractive electronic band structure and increased physicochemical stability. C3N4 constitutes a photocatalyst with a lot of photoredox applications in artificial photosynthesis, environmental remediation and degradation of pollutants. As far as the photocatalytic CO2 reduction is concerned, the adsorption of CO2 on the surface of C3N4 based photocatalyst is the first step of the reaction mechanism. In case of the combination of C3N4 with metal complexes such as those of Pt, C3N4 acts as a visible light harvesting system and catalyst whereas Pt complex provides the CO2 active sites. The complex method of photocatalytic reduction of CO2 emissions in the presence of photocatalyst can be done using previously published methods. The pristine C3N4 (g-C3N4 and p-C3N4) and platinum doped C3N4 photocatalysts with 3 wt. % of Pt were prepared by two different ways. The prepared photocatalysts were investigated for the photocatalytic reduction of CO2 in a custom-built batch photoreactor irradiated by 8W Hg lamp. The main reaction products were detected methane, hydrogen and carbon monoxide which were analyzed in a gas chromatograph with a barrier discharge detector (BID). The physico-chemical properties of photocatalysts were characterized in detail by low-temperature nitrogen physisorption, X-ray powder diffraction and diffuse reflectance UV-Vis spectroscopy. The highest yields of CH4, H2 and CO were achieved in the presence of 3 wt. % Pt/p-C3N4. The correlation between the textural, optical and photoelectrochemical properties and the photocatalysts activity was a subject of this research.