Fig. 4: In situ UV-vis signal as a function of time, diffuse reflectance UV-vis spectra of TiO2 and Au/TiO2, and TEM image of Au/TiO2.

a UV-vis signal (integrated reflectance between 750 and 950 nm) as a function of time during CO oxidation, CO adsorption, and O2 adsorption at 20 and 100 °C. Experimental condition: 30 mL min−1 of 1% CO and/or 1% O2 in He were flowed through the cell during the first half-cycle; the modulation period was 200 s; 8 cycles were measured and averaged to enhance the signal. b Diffuse reflectance UV-vis spectra of TiO2 and Au/TiO2. c TEM image of Au/TiO2.