273714 CO2 Photoreduction Key Step Study: The Adsorption of CO2 On TiO2 Surfaces in the Presence of Co-Catalyst
Using solar energy to convert to hydrocarbon fuels has been a promising area of research since it addresses two major challenges facing the planet: production of renewable energy while reducing CO2 emissions. However, the hydrocarbon production rate achieved so far is still in the µmol/hr range. Therefore it is desirable to search for new photocatalysts that can enhance the conversion of CO2. Titania with added metal co-catalysts is a promising approach for enhancing the reaction rate. It is believed that the reduction of to on the TiO2 surface is the first and important step for photoreduction mechanism[1, 2]. This key step relies on the adsorbed forms on the TiO2 surface. Smaller bond angles facilitates the transfer of photoexcited electrons from TiO2 to CO2 due to the lowering of LUMO energy level. Many research groups have studied the appropriate TiO2 surfaces for favored adsorbed forms which facilitate this electron transfer [4-6]. However the effect of co-catalyst on TiO2surfaces on the CO2 bond breaking have not been studied in the past.
The main objective of this work is to study the effect of Ag co-catalyst on TiO2 for photoreduction in order to design specific reaction surfaces that could interact sufficiently with the to form smaller angle adsorbed species. We consider (001), (101), and (100) surfaces of anatase, and (110) and (011) surfaces of rutile with Ag present. The adsorption sites for Ag and were chosen based on literature[6-9]. Gaussian (for cluster model) and Vienna Ab Initio Simulation package (VASP)(for periodic model), are both used to study the various adsorbed forms of CO2 on TiO2 . The existence of co-catalyst on the model surfaces influences the interactions between and TiO2 surfaces. The goal is to achieve a better understanding of the bond cleavage mechanism in order to design more efficient photocatalysts for reduction to light hydrocarbon fuels.
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