Since the industrial revolution, an increased demand on fossil fuels as the predominant source of global energy have brought upon many harmful consequences, such as environmental pollution, climate change, and depletion of Earth’s non-renewable natural resources. Proton-Exchange Membrane (PEM) fuel cells are being researched as an alternative to generate electricity and hydrogen gas is used as fuel. However, hydrogen gas is not abundant in nature and has to be derived from hydrogen containing molecules like fossil-fuel hydrocarbons. Complex alcohols and carbohydrates are a sustainable alternative. These compounds contain long chains of hydrogen, oxygen, and carbon atoms. Transition metal catalysts, such as rhodium (Rh), can be used to break the C-H, O-H, and C-C bonds of these molecules to release hydrogen gas as byproduct. But a better understanding of the catalytic reaction mechanisms is needed to fully utilize complex alcohols for hydrogen generation. For this research, the computational method periodic density functional theory (DFT) is used to investigate C-H and O-H bond cleavage over a Rh metal catalyst. There are different types of catalytic metal lattice structures, such as planar, stepped, and kink surfaces. Recent studies have shown that the stepped and kink surfaces are more reactive and allow compounds to bind much stronger to the metal surface. By using periodic DFT, this project will investigate the reaction mechanisms for breaking C-H and O-H bonds of alcohols using an extended stepped Rh(211) catalyst surface. The results will be compared to previous research done on the O-H and C-H bond cleavage of the same alcohols on a planar Rh(111) surface to further understand the catalytic properties of the stepped rhodium surface.
