水和碳酸盐对二氧化碳光催化成甲烷的影响.pdf

ARTICLE /JACS Role of Water and Carbonates in Photocatalytic Transformation of CO2 to CH4 on Titania Nada M. Dimitrijevic,*,†,‡ Baiju K. Vijayan,# Oleg G. Poluektov,† Tijana Rajh,‡ Kimberly A. Gray,# Haiying He,§ and Peter Zapol§,† †Chemical Sciences and Engineering Division, ‡Center for Nanoscale Materials, and §Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, United States #Department of Civil Environmental Engineering, Northwestern University, Evanston, Illinois 60208, United States S Supporting Information b ABSTRACT: Using the electron paramagnetic resonance technique, we have elucidated the multiple roles of water and carbonates in the overall photocatalytic reduction of carbon dioxide to methane over titania nanoparticles. The formation of H atoms (reduction product) and •OH radicals (oxidation product) from water, and CO - radical anions (oxidation product) from carbonates, was detected in CO -saturated 3 2 titania aqueous dispersion under UV illumination. Additionally, methoxyl, •OCH , and methyl, •CH , 3 3 radicals were identified as reaction intermediates. The two-electron, one-proton reaction proposed as an initial step in the reduction of CO2 on the surface of TiO2 is supported by the results of first-principles calculations. ’INTRODUCTION potentials are presented in reference to NHE at pH 7. Photocatalytic reducti