H, OH and COOH functionalized magnesium phthalocyanine as a catalyst for oxygen reduction reaction (ORR) – A DFT study

Abstract

Platinum is an efficient catalyst for a fuel cell, however of its high cost and rarity on Earth, it becomes necessary to predict an effective, low cost, and abundantly available catalyst. Here, hydrogen (H), hydroxyl (OH) and carboxyl (COOH) group functionalized magnesium phthalocyanine (MgPc) are considered as catalysts to enhance oxygen reduction reaction (ORR) mechanism via direct four-electron reduction reaction. The density functional theory (DFT) based results show that the reactions occur on the top site of the magnesium (Mg) metal center than the edge site of the phthalocyanines (Pcs). From thermochemical parameters, the reactions are highly exothermic, hence feasible. The atoms in molecules (AIM) analysis reveals that the adsorbates stabilize over catalysts through ionic, covalent, hydrogen and weak interactions. The adsorption energy and reversible potential of the intermediates and product on phthalocyanines shows that MgPc(OH)16 is a better catalyst for the ORR process. Conclusively, this study establishes that phthalocyanines are promising materials as a catalyst for ORR which is vital for fuel cell applications.