Mechanisms Leading to Alkali Oxidation on Metal Surfaces

The role of potassium promoter in surface carbon hydrogenation on Hägg carbide surfaces

“…Although many studies focused on promotion effect of alkali metals on metal surfaces [10][11][12], the mechanisms in affecting the performance of catalysts still remain controversially.…”

Theoretical study of the influence of Na on CO adsorption and dissociation on Pd(111): Long-range or short-range interactions between co-adsorbates?

“…Alkali metal (AM) additives, usually used as promoters in many catalytic reactions [1,2] have been always a hot topic both experimentally [3][4][5][6] and theoretically [7][8][9][10] in heterogeneous catalysis and surface science. Four types of interactions between AMs and co-adsorbates have been suggested to explain its promotional effects in literature so far: direct orbital overlap [7] between the AM and the adsorbate ($3 Å), short-range ($4 Å) electrostatic interaction [7,11,12] of the alkali-induced electric field with the adsorbate-surface bond, long-range indirect interaction through surface electrons [13], and non-local or long-range surface polarizability enhancement [10].…”

O2 dissociation in Na-modified gold ultrathin layer on Cu(111)

“…Thus this mode should not be observed in the scattering regime of these experiments. We assign this feature to the broad zone-center optical phonon [139,140] Beside the Na-Cu vibration [141][142][143], which shifted from 19 down to 17 meV upon CO adsorption due to the CO-induced lengthening of the alkali-substrate bond [144][145][146][147], also the Na-O vibration at 36 meV has been revealed [114,148]. This is ascribed to the dissociative adsorption of CO on alkali-promoted Cu(111) which we have recently demonstrated elsewhere [149].…”

“…A constant sticking coefficient was assumed to obtain other desired Au and Na coverage. A particular care has been devoted to avoid contamination of alkalis [16,114,132,135].…”

“…For these reasons, the study of alkali promotional effects on surfaces and interfaces continues to be one of the main topics of surface science [110][111][112][113][114][115][116][117][118][119][120][121].…”