O₂Activation by Metal Surfaces: Implications for Bonding and Reactivity on Heterogeneous Catalysts

Abstract

The activation of O on metal surfaces is a critical process for heterogeneous catalysis and materials oxidation. Fundamental studies of well-defined metal surfaces using a variety of techniques have given crucial insight into the mechanisms, energetics, and dynamics of O adsorption and dissociation. Here, trends in the activation of O on transition metal surfaces are discussed, and various O adsorption states are described in terms of both electronic structure and geometry. The mechanism and dynamics of O dissociation are also reviewed, including the importance of the spin transition. The reactivity of O and O toward reactant molecules is also briefly discussed in the context of catalysis. The reactivity of a surface toward O generally correlates with the adsorption strength of O, the tendency to oxidize, and the heat of formation of the oxide. Periodic trends can be rationalized in terms of attractive and repulsive interactions with the d-band, such that inert metals tend to feature a full d band that is low energy and has a large spatial overlap with adsorbate states. More open surfaces or undercoordinated defect sites can be much more reactive than close-packed surfaces. Reactions between O and other species tend to be more prevalent than reactions between O and other species, particularly on more reactive surfaces.

The Metal Type Governs Photocatalytic Reactive Oxygen Species Formation by Semiconductor‐Metal Hybrid Nanoparticles

“…Bard and co‐workers reported on H 2 O 2 production on different electrocatalyst materials concluding that the number of transferred electrons to O 2 molecule is closer to 4 in the case of Pt (forming 2H 2 O) while for Au it is closer to 2 (forming H 2 O 2 ) . Although the decrease in metal size in these HNPs in comparison to the reported literature is known to activate the metal surface, the selectivity towards H 2 O 2 is still preserved in the nano‐size regime . This is also consistent with the prior report of better photocatalytic H 2 O 2 formation on TiO 2 ‐Au compared to TiO 2 ‐Pt …”

Regulating the Catalytic Dynamics Through a Crystal Structure Modulation of Bimetallic Catalyst

“…Pt or Pd alloys containing transition metals (e.g., Co, Ni, Fe, Cu, Mn, etc.) have represented the most excellent ORR/OER activities, which are well demonstrated from a traditional viewpoint that the electronic structures of catalysts are closely related to the contents of transition metals . Recently, the research on the surface structure of solid catalysts has drawn a great interest because the active sites and adsorption behaviors of key reactants highly depend on catalyst surface .…”

Surface Modification for Promoting Durable, Efficient, and Selective Electrocatalysts

“…The nanostructuring of noble and non‐noble metals with the manipulation of particle shape/size or the engineering of topmost layers with sub‐monolayer of foreign metals is the subject of ongoing research. These strategies allow great progress in the field and have been extensively reviewed, e. g . to quote a few.…”