273714 CO2 Photoreduction Key Step Study: The Adsorption of CO2 On TiO2 Surfaces in the Presence of Co-Catalyst

Wednesday, October 31, 2012
Hall B (Convention Center )
Chi-Ta Yang1, Nianthrini Balakrishnan2, Babu Joseph2 and Venkat Bhethanabotla2, (1)Chemical and Biomedical Engineering, University of South Florida, Tampa, FL, (2)Chemical and Biomedical Engineering, Clean Energy Research Center, University of South Florida, Tampa, FL

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[1]. 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[3]. 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.

References

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2. Usubharatana, P., et al., Photocatalytic Process for CO2 Emission Reduction from Industrial Flue Gas Streams. Industrial & Engineering Chemistry Research, 2006. 45(8): p. 2558-2568.

3. Freund, H.J. and M.W. Roberts, Surface chemistry of carbon dioxide. Surface Science Reports, 1996. 25(8): p. 225-273.

4. Indrakanti, V.P., J.D. Kubicki, and H.H. Schobert, Quantum Chemical Modeling of Ground States of CO 2 Chemisorbed on Anatase (001), (101), and (010) TiO 2 Surfaces. Energy & Fuels, 2008. 22(4): p. 2611-2618.

5. Indrakanti, V.P., H.H. Schobert, and J.D. Kubicki, Quantum Mechanical Modeling of CO2 Interactions with Irradiated Stoichiometric and Oxygen-Deficient Anatase TiO2 Surfaces: Implications for the Photocatalytic Reduction of CO2. Energy & Fuels, 2009. 23(10): p. 5247-5256.

6. He, H., P. Zapol, and L.A. Curtiss, A Theoretical Study of CO2 Anions on Anatase (101) Surface. The Journal of Physical Chemistry C, 2010. 114(49): p. 21474-21481.

7. Mazheika, A.S., et al., Theoretical Study of Adsorption of Ag Clusters on the Anatase TiO(2)(100) Surface. Journal of Physical Chemistry C, 2011. 115(35): p. 17368-17377.

8. Dan C. Sorescu, W.A.A.-S., and Kenneth D. Jordan, CO2 adsorption on TiO2(101) anatase: A dispersion-corrected density functional theory study. Journal of Chemical Physics, 2011. 135(12): p. 17.

9. Dan C. Sorescu, J.L., Wissam A. Al-Saidi, and Kenneth D. Jordan, CO2 adsorption on TiO2(110) rutile: Insight from dispersion-corrected density functional theory calculations and scanning tunneling microscopy experiments. Journal of Chemical Physics, 2011. 134(10): p. 12.


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