Optimum molar ratio of H₂ and H₂O to reduce CO₂ using Pd/TiO₂

Abstract

This study investigated the optimum moral ratio of CO₂ and reductants H₂O and H₂ to obtain high CO₂ reduction performance of Pd/TiO₂ photocatalyst. The Pd/TiO₂ film photocatalyst is prepared by sol-gel and dip-coating process to form TiO₂ film and by pulse arc plasma method to dope Pd. The prepared Pd/TiO₂ film was characterized by SEM, EPMA and EELS. The impact of overlapping two Pd/TiO₂ films on CO₂ reduction performance was also investigated to utilize the light and prepared photocatalyst more effectively. Moreover, this study investigated the characteristics of Pd/TiO₂ film to reduce CO₂ under the illumination condition of Xe lamp with or without ultraviolet (UV) light. It is found when the moral ratio of CO₂/H₂/H₂O is set at 1:0.5:0.5, the best CO₂ reduction performance has been obtained under the illumination conditions of Xe lamp with and without UV light. It is revealed that the moral quantity of CH₄ per weight of photocatalyst for overlapped Pd/TiO₂ film is 8.14 μmol/g for the moral ratio of CO₂/H₂/H₂O of 1:0.5:0.5 under the illumination condition of Xe lamp with UV light, which is approximately 1.1 times larger than that for one Pd/TiO₂ film. It can be concluded that the optimum moral ratio of CO₂/H₂/H₂O, for the CO₂ reduction reaction, is 1:0.5:0.5.