Gold Nanoparticles Supported on Carbon Nitride: Influence of Surface Hydroxyls on Low Temperature Carbon Monoxide Oxidation

Abstract

This paper reports the synthesis of 2.5 nm gold clusters on the oxygen free and chemically labile support carbon nitride (C 3 N 4 ). Despite having small particle sizes and high enough water partial pressure these Au/C 3 N 4 catalysts are inactive for the gas phase and liquid phase oxidation of carbon monoxide. The reason for the lack of activity is attributed to the lack of surface −OH groups on the C 3 N 4 . These OH groups are argued to be responsible for the activation of CO in the oxidation of CO. The importance of basic −OH groups explains the well documented dependence of support isoelectric point versus catalytic activity.

Controlling activity and selectivity using water in the Au-catalysed preferential oxidation of CO in H2

“…Surface hydroxyl groups on the support are clearly necessary for the most-active catalysts [24][25][26] , and we showed 11 , following work by the Haruta 27,28 , Davis 26,29 , Fujitani 30 and Iglesia 31 groups, that water greatly enhances reaction rates. Several groups also suggested that oxygen vacancies on the support play in important mechanistic role [32][33][34] .…”

BiOBr/protonated graphitic C3N4 heterojunctions: Intimate interfaces by electrostatic interaction and enhanced photocatalytic activity

“…However, the poor separation rate of photoinduced carriers seriously limits its photocatalytic activity [28]. For further improving the photocatalytic activity of g-C 3 N 4 , varieties of methods have been proposed, such as doping with metal or nonmetal [29][30][31][32], introduction of mesoporosity [33,34], as well as compositing with other semiconductors. The key to fabrication of g-C 3 N 4 based heterojunctions is to seek heterogeneous semiconductors that possess overlapping band structure with g-C 3 N 4 .…”

The critical role of water at the gold-titania interface in catalytic CO oxidation

“…Experimental studies indicate that materials lacking OH groups are inactive (24,25), yet, the dominant mechanistic models vary in the suggested role of support OH groups and generally highlight the possible role of oxygen vacancies (16,17,(22)(23)(24)26). Computational models also have not indicated a clear mechanistic role for the support OH groups, and isotopelabeling studies indicate that CO and O 2 react without incorporating oxygen from the support (21,27).…”