Second-harmonic generation and theoretical studies of protonation at the water/α-TiO2 (110) interface

The pH of zero net surface charge (pH(pzc)) of the alpha-TiO2 (110) surface was characterized using second-harmonic generation (SHG) spectroscopy. The SHG response was monitored during a series of pH titrations conducted at three NaNO3 concentrations. The measured pH(pze) is compared with a pH(pzc) value calculated using the revised MUltiSIte Complexation (MUSIC) model of surface oxygen protonation. MUSIC model input parameters were independently derived from ab initio calculations of relaxed surface bond lengths for a hydrated surface. Model (pH(pzc) 4.76) and experiment (pH(pzc) 4.8 +/- 0.3) agreement establishes the incorporation of independently derived structural parameters into predictive models of oxide surface reactivity. (c) 2005 Elsevier B.V. All rights reserved.