Carbon on transition metal surfaces

The review surveys the conditions of formation and properties of four forms of surface carbon on transition metals, to wit, adsorbed atoms and clusters, surface carbide and graphite, and their role in the physical and chemical processes on the surface. The first-order phase transition in the adlayer, when graphite islands coexist with carbon gas, are considered. The effect of intercalation, when atoms (Cs, K, Na, Ba, Pt, Si) penetrate spontaneously under the graphite islands physisorbed on the metal, and its mechanism are discussed. An analysis is made of the poisoning of platinum-group metal catalysts in the reaction of dissociation, when graphite islands characterized by extreme adsorption and catalytic passivity form in the adlayer. The method of CsCl dissociation to probe the surface carbon is treated. Attention is drawn to the adsorption of a number of atoms (Cs, K, Ba, Pt) on a graphite monolayer on metals, and the properties of such systems are discussed. The effects observed in coadsorption of CsCl molecules with K, Na, Ba, Tm atoms on a graphite monolayer on metals are covered. By analogy with the bulk carbides, surface carbides of fixed stoichiometry and very strong metal-carbon bonding have been revealed to form on the surface of transition metals (W, Re, Mo). The effect of displacement of surface carbon into the bulk of the metal stimulated by the adsorption of some atoms (Si, S, O) is discussed. The carbon clusters adsorbed on metals are considered. The transport of surface carbon, its desorption and diffusion between the surface and the bulk of the metal with a single- and double-phase adlayer are reviewed.