Accurate determination of the CO coverage at saturation on a cyanide-modified Pt(111) electrode in cyanide-free 0.5 M H2SO4

Quantitative Study of Non‐Covalent Interactions at the Electrode–Electrolyte Interface Using Cyanide‐Modified Pt(111) Electrodes

“…Experimental details have been reported previously [13][14][15][16]20] and can be found in the Supporting Information. All the potentials in the text are referred to the RHE.…”

“…As a consequence, trigonal adsorption and reaction sites are lacking on cyanidemodified Pt(111) electrodes while, at the same time, the uncovered Pt atoms in the troughs separating the hexagonal CN rings remain unaffected. [12][13][14] Thanks to this peculiar property, we have successfully used cyanide-modified Pt(111) electrodes as model surfaces to investigate the role of atomic ensembles in electrocatalysis [14][15][16] and to develop new concepts for the rational design of cathode catalysts for the ORR in phosphoric acid fuel cells (or in any environments containing strongly adsorbing tetrahedral anions, like the proton exchange membrane fuel cells, PEMFCs). [4] Herein we present a combined theoretical and experimental study of non-covalent interactions between alkaline metal cations and cyanide-modified Pt(111) electrodes, aimed at deepening our understanding of the factors governing non-covalent interactions in surface electrochemistry and at highlighting their often neglected importance.…”

“…[4,12,13] It has been shown that the cyanide adlayer on Pt(111) is remarkably stable, no change being observed in the CVs of the cyanide-covered electrode upon repetitive cycling between 0.05 and 1.10 V versus the reversible hydrogen electrode (RHE). A very interesting aspect is the 0.20 V positive shift of the onset of hydrogen adsorption [corresponding to a ca.…”

“…This behavior has been attributed to the formation of (CN ad ) x -H clusters due to non-covalent (electrostatic) interactions between the negative end of the CN ad dipole and the oppositely charged H + . [4] CN ad acts as an inert site blocker (third body effect) [4,[12][13][14][15][16] and, hence, will not affect the energetics of the PtÀH upd bond. The analysis of the density of states (DOS) for the topmost Pt atoms (Figure 1), shows that the DOS of the Pt atoms directly bonded to the CN ad is shifted to lower energies, this being consistent with a strong bonding (the binding energy was calculated to be À3.19 eV per CN).…”

Atomic Ensemble Effects in Electrocatalysis: The Site‐Knockout Strategy

“…Huerta et al [26d] were the first to realise, based on the fact that the hydrogen and OH adsorption regions can still be observed in the cyclic voltammogram of a Pt(111) electrode after adsorption of a saturated cyanide adlayer (see Figure 4), that a cyanide-covered Pt(111) electrode can be considered as a chemically modified electrode (hence the term cyanide-modified Pt(111) electrode introduced by us [30] ). Furthermore, it was found that cyclic voltammograms of a cyanide-modified Pt(111) electrode in 0.1 m HClO 4 and in 0.1 m H 2 SO 4 are nearly identical, [26d] which suggests that adsorbed CN groups act as a third body that blocks the sites necessary for the adsorption of sulphate on Pt.…”