Surface electronic properties and CO hydrogenation activity of nickel deposited on rutile TiO₂(100) as a model supported catalyst

A combined ultrahigh-vacuum surface analysis-high-pressure cell system has been used to study the electronic properties and CO hydrogenation behavior of nickel deposited on single-crystal rutile TiO₂(100) as a model supported catalyst. Photoemission studies show that nickel atoms at the Ni TiO₂(100) interface are negatively charged. In situ CO hydrogenation studies at a total pressure of 80 Torr have been performed on Ni TiO₂(100) and Ni(111) from 170 to 270 °C. The methane turnover number of Ni TiO₂(100) is a function of the Ni coverage and attains a maximum at an average Ni thickness of 5 Å the methanation activity of 5 Å Ni TiO₂ is a factor 3.3-3.7 times that of Ni(111), with an accompanying shift of the product distribution toward higher hydrocarbons.