Correlation of H Adsorption Energy and Nanoscale Elastic Surface Strain on Rutile TiO2(110)

Abstract

Scanning tunneling microscopy (STM) has been used to obtain the aerial distribution of bridge-bonded hydroxyl groups (HOb) on a rutile TiO2(110) surface, modified with a well-defined nanoscale strain field. Our study makes use of earlier findings that 5–30 nm wide locally strained areas of the surface can be formed via low-energy Ar-ion bombardment combined with a thermal treatment. These strained areas appear as protrusions in the STM images, resulting from subsurface argon-filled cavities. Our STM images show that the local surface concentration of OHb groups is lower on the protrusions. This lowering of concentration has been interpreted as a reduction in the local H absorption energy, ΔE, a result similar to that observed on metals. In this paper, analysis of the reduction in this O–H bond energy across the surface shows a strong correlation between ΔEOH and the characteristic surface strain value, S. The ΔEOH values have been calculated through a subtraction of the contribution of the repulsive dipol...