The dark adsorption experiments were firstly carried out to show the effect of the liquid-N2 quenching on the MB adsorption on TiO2 surface (see Fig. S4). The amounts of relative dark adsorptions of the nTiO2 and q-TiO2 are shown in Fig. 8 (A), which show that the MB dark adsorption on the n-TiO2 increases with the preannealing temperatures, while that on the q-TiO2 tends to decrease. The change in MB dark adsorption indicates an change in surface chemical structure, in good line with the above analysis. MB belongs to an anion dye favoring to combine with a negatively charged surface. Therefore, this result may imply that some negative charge species other than hydroxyl groups might be introduced onto TiO2 surface by the liquid N2 quenching, which cannot be detected by XPS.