Enhanced OER activity of FePc molecule by substrate effects: A first principles study

Electrolysis of water is a clean, sustainable and efficient way to produce hydrogen, and will be indispensable among the production of renewable energy in the future. The oxygen evolution reaction (OER) plays a key role of water decomposition. Here, we attached iron phthalocyanine to graphene, and explored the influence of different graphene substrates to catalytic activity using the first-principles methods based on density functional theory. Graphene improves the dispersion and electrical conductivity of iron phthalocyanine molecules, and facilitates its OER activity. The introduction of substrate promotes the electron transfer between FePc and the oxygen-containing intermediates. The results indicated that the iron phthalocyanine exhibits different OER activity on various graphene substrates, among which the defective graphene most promoted the OER activity. The improved activity is originated from the axial interaction between the iron and carbon atoms on the defective graphene, leading to a moderate adsorption of oxygen-containing intermediates. Our study provides a reference for the regulation of molecular catalyst activity.