Preferential oxidation of carbon monoxide in hydrogen using zinc oxide photocatalysts promoted and tuned by adsorbed copper ions

摘要

Preferential oxidation of CO (63 Pa) and O _2 (76 Pa) in H _2 (6.3 kPa) using spheroidal ZnO nanoparticles (22 nm × 47 nm) converted 52% of CO into CO _2, and selectivity to CO _2 was 92 mol% under UV-visible light for 5 h. When 0.5 wt.% of Cu ~(2+) was adsorbed on ZnO, 91% of CO was converted into CO _2 with a selectivity of 99 mol% under UV-visible light for 3 h. CO (63 Pa) was photocatalytically decreased to 2.3 mPa (0.35 ppm) in O _2 (150 Pa) and H _2 (6.3 kPa) for 5 h with a selectivity of 94 mol%. As evident from a XANES peak at 8983.1 eV, the surface Cu ~(II) sites trapped photogenerated electrons. Furthermore, O _2-derived species were reduced by accepting electrons from Cu ~I and protons from the neighboring formate species, as indicated by the FT-IR peaks at 2985, 2879, 1627, 1587, and 1297 cm ~(-1).