나피온으로 개질된 Pd-TiO2 를 이용한 이산화탄소의 탄화수소 전환

Abstract

The photocatalytic reduction of CO2 is a promising method to reduce excess CO2 present in the atmosphere, and simultaneously produce solar fuels (e.g. CO, CH4 and CH3OH) by means of an environmental friendly (green chemistry) approach. In general, CO2 is reduced through proton-coupled multielectron transfer (PCET) to avoid low reduction potential of CO2 by one electron transfer. Therefore, the concentration of proton ion is one of key factor in CO2 reduction. In this study, Nafion (perfluorinated polymer with sulfonate groups) coated Pd-TiO2 (Nf/Pd-TiO2) was prepared and their reactivity for the photocatalytic CO2 reduction was estimated after the catalyst pretreatment. The Nf/Pd-TiO2 powder was characterized by HR-TEM, ELS, XPS, and zeta potential measurements. The role of the Nafion layer is to provide high proton concentration within the layer to facilitate PCET reactions and to retard the oxidative degradation of intermediates and products of CO2 reduction. Nf/Pd-TiO2 is more active than Pd-TiO2 for the photo-production of hydrocarbons (e.g., methane, ethane, and propane). The photosynthetic activity of Nf/Pd-TiO2 catalyst was maintained through repeated cycles of photoreaction, which confirms the stability of Nafion layer.