Subsurface Carbon: A General Feature of Noble Metals

Ain't Misbehavin': Accurate density functional simulations on suited surface and nanoparticle atomistic models establish the energetic and kinetic feasibility of subsurface C atoms in Cu, Ag, and Au noble coinage metals. The subsurface carbon can thus be regarded as a key player in heterogeneously catalysed surface processes.

Abstract

Carbon moieties on late transition metals are regarded as poisoning agents in heterogeneous catalysis. Recent studies show the promoting catalytic role of subsurface C atoms in Pd surfaces and their existence in Ni and Pt surfaces. Here energetic and kinetic evidence obtained by accurate simulations on surface and nanoparticle models shows that such subsurface C species are a general issue to consider even in coinage noble‐metal systems. Subsurface C is the most stable situation in densely packed (111) surfaces of Cu and Ag, with sinking barriers low enough to be overcome at catalytic working temperatures. Low‐coordinated sites at nanoparticle edges and corners further stabilize them, even in Au, with negligible subsurface sinking barriers. The malleability of low‐coordinated sites is key in the subsurface C accommodation. The incorporation of C species decreases the electron density of the surrounding metal atoms, thus affecting their chemical and catalytic activity.

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