Mechanistic insights into biomimetic CO2hydration activity of titania nanoclusters

Anatase TiO2, a widely used semiconductor metal oxide support, was tested for biomimetic carbonic anhydrase activity catalyzing the reversible hydration of CO(2)to bicarbonate ions. Owing to superior photocatalytic response of nanoclusters of TiO(2)and its apparent role in catalyzing CO(2)hydration, (TiO2)(15)nanocluster was tested for the reaction using density functional theory calculations. Free energy landscape of the reaction was developed following the biological mechanism consisting of H2O adsorption, deprotonation, CO(2)complexation, CO(2)bending, intramolecular proton transfer, and bicarbonate ion displacement. The identity of the intermediates of the mechanistic cycle was further confirmed by computational nuclear magnetic resonance and infrared spectroscopic studies. A close correspondence of the computational and reported experimental spectroscopic analyses confirmed the identity of the intermediates and the presence of biomimesis over the TiO2 cluster.