CO oxidation on nanosized Au/Al2O3 by surface hydroxyl groups and in the absence of O2, studied by inverse gas chromatography

Thermal CO Oxidation and Photocatalytic CO2 Reduction over Bare and M-Al2O3 (M = Co, Ni, Cu, Rh, Pd, Ag, Ir, Pt, and Au) Cotton-Like Nanosheets

“…The group 11 (Au, Ag, and Cu) and the period 4 (Co, Ni, and Cu) elements showed much poor catalytic activity on the Al 2 O 3 support. Additionally, the onset temperatures of Au and Ag-loaded Al 2 O 3 nanosheets were unexpectedly even higher than expected [ 6 , 10 , 15 ]. In other words, the Au- and Ag-loaded Al 2 O 3 nanosheets showed poorer CO oxidation activity.…”

“…This was attributed to metallic Ag [6,32,36]. The shoulder [15,31,32]. The corresponding satellite peaks for Ni 2+ were clearly observed around 880 eV and 862 eV.…”

“…For Ni-Al 2 O 3 nanosheets, Ni 2p 1/2 and Ni 2p 3/2 XPS peaks were observed at binding energies (BEs) of 873.4 eV and 856.1 eV, respectively, with a spin-orbit splitting of 17.3 eV. This could be attributed to Ni 2+ of NiO and Ni(OH) 2 [ 15 , 31 , 32 ]. The corresponding satellite peaks for Ni 2+ were clearly observed around 880 eV and 862 eV.…”

“…In reaction (3), gaseous CO and surface O reacted to release CO 2 [ 12 , 13 ]. When moisture was present in the reaction, the surface OH group was plausibly formed and CO might also react with the surface metal hydroxide to form the CO 2 in reaction (4) [ 15 ]. On the basis of the FT-IR spectra (Supporting Information, Figure S7 ), surface OH groups were observed in the as-prepared samples.…”

“…Aluminum oxide (Al 2 O 3 ) has extensively been used as a heterogeneous catalyst in diverse catalytic reactions of CO oxidation [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19], CO 2 reduction [20][21][22][23], CO 2 methanation/hydrogenation [20,[24][25][26][27], and preferential oxidation of CO [28,29]. The efforts to increase the catalytic activity of the metal oxide have been devoted to the modification of the metal surface by loading of transition metals in groups of 9 (Co, Rh, and Ir), 10 (Ni, Pd, and Cu), and 11 (Cu, Ag, and Au).…”