Formation of isocyanate on Cu(100) from the oxidation of cyanogen and from the decomposition of isocyanic acid

Interaction of HNCO with Au(111) surfaces

“…1B). This vibration loss was detectable up to~430 K. The loss at 2170-2185 cm − 1 was also observed by different vibration spectroscopic studies on other metal single crystal surfaces, and was attributed to the asymmetric stretching of surface NCO species [14][15][16][17][18][19][20][21][22][23][24]. Accordingly adsorbed HNCO undergoes dissociation on Au(111) surface around 150 K, practically at the same temperature as the desorption of HNCO ( Fig.…”

“…The disappearance of the N\H stretching and the attenuation of the 510 and 2780 cm − 1 vibrations characteristic also to molecular HNCO, is in good harmony with the occurring of the dissociation process. This reaction proceeded easily on Pt metals [14][15][16][17][18][19][20][21][22][23][24][25], but on Cu(111) it required the presence of preadsorbed O atoms [45]. However, we cannot exclude the possibility that the method (EEL spectroscopy in the electronic range), applied earlier in the case of Cu(111) was much less sensitive than the HREEL spectroscopy used at the present.…”

“…The most important findings are as follows: (i) NCO surface species developed in the catalytic reduction of NO is formed on the metals, but after its formation it migrates onto the supports, where it is stabilized [9][10][11][12][13]. This spillover process was first clearly demonstrated in the case of Rh/SiO 2 [12], (ii) the position of the absorption band of NCO species in the IR spectra varies with the nature of oxidic supports (Al 2 O 3 , MgO, TiO 2 , CeO 2 , ZSM-5) and fell in the range of 2210-2315 cm − 1 [7][8][9][10], (iii) as was revealed by the studies performed on metal single crystals in UHV, the characteristic vibration of NCO bonded to the metals is at 2170-2190 cm − 1 , which is almost independent of the nature of the metals [14][15][16][17][18][19][20][21][22][23][24][25][26], (iv) in contrast to the NCO attached to the oxides, isocyanate on the metals is a rather unstable species, and decomposes completely around 300-330 K [14][15][16][17][18][19][20][21][22][23][24][25][26]. Theoretical calculation using the density functional formalism (DFT) disclosed more details on the adsorbate-substrate interaction on different sites of metals and greatly contributed to the better understanding of the chemistry of NCO on catalyst surfaces [27][28][29]…”

Theoretical Simulation of isocyanate (NCO) adsorption on the Ag(001) surface

“…It adsorbs dissociatively at temperatures above 120 − 140 K, yielding NCO and atomic H. The significant blue-shift of the asymmetric stretching band observed in the RAIRS spectra with increasing NCO coverage suggests a strong repulsive interaction between adsorbed NCO species. Similar RAIRS studies have also identified NCO species on Ru(100) [19,20] and Cu(100) [21] surfaces. The NCO obtained from both experiments was stable on each surface up to a temperature of 500 K.…”

Understanding and Controlling Cu-Catalyzed Graphene Nucleation: The Role of Impurities, Roughness, and Oxygen Scavenging

“…Oxygen desorbing from the surface may also oxidize adsorbed or surface bound carbon impurities, which then become volatile (in the form of CO and CO 2 25 ). In fact, our SIMS data shows evidence of increased levels of oxidized carbon species such as C 2 O and isocyanate (cyano groups have been shown to react in the presence of oxygen at elevated temperatures to isocyanate (NCO) 82−84 ) (see Figure S10). This represents a very effective way of removing deleterious carbon and to significantly reduce the GND.…”