Cooperative Surface‐Particle Catalysis: The Role of the “Active Doughnut” in Catalytic Oxidation

Abstract

We consider the factors that govern the activity of bifunctional catalysts comprised of active particles supported on active surfaces. Such catalysts are interesting because the adsorption and diffusion steps, which are often discounted in “conventional” catalytic scenarios, play a key role here. We present an intuitive model, the so‐called “active doughnut” concept, defining an active catalytic region around the supported particles. This simple model explains the role of adsorption and diffusion steps in cascade catalytic cycles for active particles supported on active surfaces. The concept has two important practical implications. First, the reaction rate is no longer proportional to the number of active sites, but rather to the number of “communicative” active sites—those available to the reaction intermediates during their respective lifetimes. Second, it generates an important testable prediction concerning the dependence of the total reaction rate on the particle size. With these tools at hand, we examine six experimental examples of catalytic oxidation from the literature, and show that the active doughnut concept gives valuable insight even when detailed mechanistic information is hard to come by.

Selective Aerobic Oxidation of Lactate to Pyruvate Catalyzed by Vanadium‐Nitrogen‐Doped Carbon Nanosheets

“…Note that vanadia supported on pure carbon nanosheets showed the highest selectivity to ethyl pyruvate of 91 %, confirming our earlier observations that the presence of carbon favors the production of ethyl pyruvate . We therefore conclude that combining vanadia active sites with nitrogen‐rich carbon support creates cooperative catalysts, boosting the catalytic oxidation of ethyl lactate to ethyl pyruvate.…”

Escaping Scaling Relationships for Water Dissociation at Interfacial Sites of Zirconia-Supported Rh and Pt Clusters

“…1,7 Numerous studies strongly advocate the vital role of support, and the metalsupport interface, for the overall catalytic activity. 6,[8][9][10][11][12] Therefore, both the metal and the support should be considered when investigating such systems computationally. The choice of the supported metal catalyst model is non-trivial; typical models employ either supported finite clusters or nanorods, and different metal-support combinations have been investigated (e.g.…”

A Multi‐Doped Electrocatalyst for Efficient Hydrazine Oxidation

“…hydrazine synthase and dehydrogenase,a nd nitrogenase) contain redox-active and earth-abundant elements such as Fe,Mo, Vand Cu, and nonmetals N, Oa nd S. [10] Importantly,s everal elements are intimately bound in these catalytic. [11,12] In this work, we focused on emulating ak ey feature of nitrogen-cycle enzymes:h aving multiple elements doping as ingle catalytic site. Moreover,e ven if several dopants are present, their separation in space prevents true cooperativity.For example,even in multi-doped particle/support HzOR catalysts, [7] only reactants located near the base of each particle base can interact with both particle and support surfaces,u nless the particles are very small.…”