On the mechanism of photocatalytic CO₂ reduction with water in the gas phase

• Published in: Catalysis today Vol. 181; no. 1; pp. 82 - 88
• Main Authors: Uner, Deniz, Oymak, Mert Mehmet
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 12-02-2012
• Subjects: catalytic activity; glass; hydrogen; methane; methane production; photosynthesis
• ISSN: 0920-5861; 1873-4308
• DOI: 10.1016/j.cattod.2011.06.019

The mechanism of photocatalytic reduction of CO₂ with H₂O over Pt–TiO₂ films produced by the sol–gel deposition over glass beads was investigated. The accumulation of significant amount of carbonaceous intermediate on the surface followed by deactivation indicated the rate limiting reaction is the water splitting reaction, similar to the natural photosynthetic systems. When gas phase hydrogen was allowed in the system, the carbonaceous intermediates were converted to methane at rates higher than the artificial photosynthesis conditions. In the presence of hydrogen, formation of methane reaction proceeded in the dark albeit at lower rates. The progress of the reaction is very similar to the natural photosynthetic reactions however the rates are seven orders of magnitude slower than the reactions in the natural photosynthetic processes. Furthermore, the role of spilled over hydrogen in the reaction was also demonstrated.