서강대학교

초록/요약

In this study, {110} crystal facet exposed CeO2 rod was used for CO2 reduction because it has the best photocatalytic property among the all kinds of crystal facets of it. It was applied and modulated with p-type NiO and rGO layer to suppress the charge carrier recombination by interface junction with NiO and to enhance multi-electrons shuttling with rGO. NiO/CeO2/rGO photocatalyst showed an enhanced photocurrent density of 13.2 μA/cm2 and short life-time of excited electron as 2.16 ns measured with time resolved photoluminescence (TRPL). Comparative in-situ XAFS plots give the evidence for the oxygen vacancy generation, which can function for CO2 activation on the {110} crystal facet of CeO2 by decreasing activation energy of photocatalytic CO2 reduction. XANES proved the increased intensity of Ce3+ and decreased intensity of Ce4+ during solar light irradiation. Through EXAFS spectra, CO2 adsorption on ceria was also confirmed by the changed bond distance between Ce-O during CO2 adsorption. Synthesized NiO/CeO2/rGO photocatalyst converted CO2 to formaldehyde in a rate of 421.09 μmol g-1 h-1. Obtained solar to fuel efficiency was 0.526%. Through in-situ FT-IR analysis, it is confirmed that CO2 reduction reaction on NiO/CeO2/rGO photocatalyst follows formaldehyde pathway.