Co-adsorption and mutual interaction of nCO + mH2 on the Fe(1 1 0) and Fe(1 1 1) surfaces

Abstract

Spin-polarized density functional theory computations have been performed to investigate nCO+mH2 co-adsorption and mutual interaction on the Fe(110) and Fe(111) surfaces. It is found that CO pre-coverage affects hydrogen adsorption strongly, while H pre-coverage hardly affects CO adsorption. It is possible to have CO+H2 co-adsorption on Fe(110), while very strong preference of CO pre-coverage on Fe(111) has been found. On Fe(111), it is also found that each CO molecule blocks on average 2H adsorption sites at all CO pre-coverage. All these findings are consistent with available experimental results. Compared with CO/H2 ratios in gas phase, CO/H2 surface ratios are very different and much more sensitive to temperature than pressure. Our results provide the basis for exploring the mechanisms of iron-catalyzed conversion of synthesis gas.