In situ infrared study of photoreaction of ethanol on Au and Ag/TiO2

• Au and Ag increased surface hydroxyl groups and the adsorption of monodentate ethoxy.
• Au and Ag enhanced electron–hole transfer rate and promoted the product formation.
• Au and Ag accelerated the formation of formate and acetate on TiO2.

An in situ IR technique was used to study the role of Au and Ag additives on photocatalytic reaction of ethanol on TiO2 at 300 K. Au and Ag additives increased water/ethanol coverage and decreased the rate of ethanol's CH scission, a step involving in scavenging photogenerated holes. Au and Ag promoted adsorption of ethanol as monodentate ethoxy, accelerated its conversion to formate (HCOO−ad) and acetate (CH3COO−ad). In contrast, adsorbed ethanol on TiO2 did not produce IR-observable products and exhibited a Stark effect with a decreased CH intensity upon accumulation of photogenerated electrons.

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