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

Abstract

Easier oxidation over gold with added water Gold adsorbed on metal oxides is an excellent catalyst for the room-temperature oxidation of CO to CO 2 . However, there has been continuing disagreement between different studies on the key aspects of this catalyst. Saveeda et al. now show through kinetics and infrared spectroscopy that the presence of water can lower the reaction activation barrier by enabling OOH groups to form from adsorbed oxygen (see the Perspective by Mullen and Mullins). The OOH then reacts readily with CO. It thus seems that the main role of oxide support and its interface with the metal is in activating water, but that the steps of the reaction that involve CO occur on gold. Science , this issue p. 1599 ; see also p. 1564

Paper‐Based N‐Doped Carbon Films for Enhanced Oxygen Evolution Electrocatalysis

“…Nowadays, there are extensive interests in studying some electrochemical reactions, such as oxygen evolution reaction (OER), hydrogen evolution reaction, oxygen reduction reaction (ORR), and carbon monoxide (CO) oxidation, which are core steps in many sustainable energy techniques 1, 2, 3, 4, 5, 6, 7. Besides enthusiastic efforts to search for new electrocatalysts to facilitate these processes, numerous studies are also devoted to making better use of the existing electrocatalysts for achieving optimal properties 2, 8, 9, 10, 11.…”

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] .…”

“…More-specific mechanistic PROX investigations by Widmann et al showed that H 2 promotes CO oxidation over Au and the same activated oxygen species is involved in both H 2 and CO oxidation 35 . There is a fairly clear consensus that, for low-temperature CO oxidation, the metal-support interface plays a critical role in the catalysis 11,30,[35][36][37][38] .…”

“…We refer to this as the 50/50 goal. Supported Au nanoparticles are wellknown to be highly active CO-oxidation catalysts [10][11][12] and notoriously poor hydrogenation catalysts 13 . They should be excellent PROX catalysts, but 20 years of research has produced very few catalysts capable of achieving the 50/50 goal (Fig.…”

On the Role of Water in Heterogeneous Catalysis: A Tribute to Professor M. Wyn Roberts

“…OH reaction pathway which other authors regard as the lowest energy pathway. Chandler and coworkers [22] express similar views to Okumura in their study of Au/TiO 2 surfaces with FTIR and isotope labelled water. They argue that there is no direct involvement of OH groups from the TiO 2 in the reaction mechanism, nor do they support the transfer of OH from TiO 2 to the gold.…”