Promoting Oxygen Reduction Reaction by Inducing Out-of-plane Polarization in Metal Phthalocyanine Catalyst.

Abstract

Metal phthalocyanine (MPc) materials with well-defined MN4 moiety offers a platform for catalyzing oxygen reduction reaction (ORR), while their practical performances are often limited by the insufficient O2 adsorption due to the planar MN4 nature. Here, we proposed a design (called as Gr-MG -O-MP Pc) that the metal of MPc (MP ) is axially coordinated to a single metal atom in graphene (Gr-MG ) through a bridge-bonded oxygen atom (O), introducing effective out-of-plane polarization to promote O2 adsorption on MPc. Manipulating the out-of-plane polarization charge by varying types of MP and MG (MP = Fe/Co/Ni, MG = Ti/V/Cr/Mn/Fe/Co/Ni) in the axial coordination zone of -MG -O-MP - were examined by density functional theory simulations. Among them, the catalyst of Gr-V-O-FePc stands out with the highest calculated O2 adsorption energy, which was synthesized successfully and verified by systemic X-ray absorption spectroscopy measurements. Importantly, it delivered a remarkable ORR performance with half-wave potential of 0.925V (versus RHE) and kinetic current density of 26.7mA cm-2 . This thus demonstrates a new and simple way to pursue high catalytic performance by inducing out-of-plane polarization in catalysts. This article is protected by copyright. All rights reserved.