Reduction of NO Adlayers on Pt(110) and Pt(111) in Acidic Media:  Evidence for Adsorption Site-Specific Reduction

Abstract

We present a combined in situ Fourier transform infrared reflection-absorption spectroscopy and voltammetric study of the reduction of saturated and subsaturated NO adlayers on Pt(111) and Pt(110) single-crystal surfaces in acidic media. The stripping voltammetry experiments and the associated evolution of infrared spectra indicate that different features (peaks) observed in the voltammetric profile for the electrochemical reduction of NO adlayers on the surfaces considered are related to the reduction of NO(ads) at different adsorption sites and not to different (consecutive) processes. More specifically, reduction of high- and intermediate-coverage (ca. 0.5-1 monolayers (ML)) NO adlayers on Pt(110) is accompanied by site switching from atop to bridge position, in agreement with the ultra-high-vacuum data. On Pt(111) linearly bonded (atop) NO and face-centered cubic 3-fold-hollow NO species coexist at high coverages (0.25-0.5 ML) and can be reduced consecutively and independently. On Pt(111) and Pt(110) electrodes, linearly bonded NO species are more reactive than multifold-bonded NO species. Both spectroscopic and voltammetric data indicate that ammonia is the main product of NO(ads) reduction on the two surfaces examined.

Redox transformations of adsorbed NO molecules on a Pt(100) electrode

“…The study was carried out using the technique of electrode surface preparation and cleaning developed in the works of Clavilier et al [22][23][24][25]. The electrode Pt(100) with the working surface area of 0.035 cm 2 was obtained after orientation, cutting and polishing of spherical single crystals.…”

“…Attention to these processes does not wane due to its fundamental and applied importance. As the reduction of nitrogen-containing compounds is a structure-sensitive process, the investigations performed at single crystal electrodes are of greatest interest [1][2][3][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35]. The use of the electrodes with clearly characterized surface structure allows revealing the correlations between electrochemical activity of adsorption sites and their structure.…”

Theoretical Studies of Substitutionally Doped Single-Walled Nanotubes

“…Nitrogen monoxide has a doublet ground state, and it is its radical character that dictates its role in biology [136]. Although Pt surfaces are known to interact with NO [188,[209][210][211], its use as a ligand for transition metal complexes is much less general (although the related NO + and NO − find widespread usage). Since the NO adsorbate has an unpaired electron, spin selection rules dictate that the resulting nanotubeadsorbate complex must also have an electronic state of doublet.…”

Atomistic Insights into Nitrogen-Cycle Electrochemistry: A Combined DFT and Kinetic Monte Carlo Analysis of NO Electrochemical Reduction on Pt(100)

“…Indeed, as we will show, the electrochemistry of NO has numerous analogies to CO 2 electroreduction, which is currently being studied by many research groups. [18][19][20][21][22] NO electroreduction has been studied under a variety of electrochemical reaction conditions, including reactions on different metal electrodes, 7,12,[23][24][25][26] varying NO concentrations, 11,27 and different liquid phase electrolytes. 23 This surface reaction has a rich chemistry and contains numerous reaction steps and intermediates.…”

“…[18][19][20][21][22] NO electroreduction has been studied under a variety of electrochemical reaction conditions, including reactions on different metal electrodes, 7,12,[23][24][25][26] varying NO concentrations, 11,27 and different liquid phase electrolytes. 23 This surface reaction has a rich chemistry and contains numerous reaction steps and intermediates. Thermodynamically, the most favorable product is N 2 ; in electrochemical experiments, however, other products, such as NH 4 OH + , NH 4 + , and N 2 O, 7,[9][10][11]28 are generally observed.…”