Metal organic framework-derived oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalysts

Access full-text files

Date

2019-08-22

Authors

Agarwal, Soham

Journal Title

Journal ISSN

Volume Title

Publisher

Abstract

The need for environmentally friendly, renewable energy had driven interest in metal-air batteries as energy storage devices due to their high energy density and better safety than lithium-ion batteries. Two reactions are key to the functioning of these systems: the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER), both of which suffer from sluggish kinetics and require catalysts to provide practical performance. Metal organic frameworks (MOFs) are a class of materials consisting of organic ligands linking metal centers and are very promising as precursors for development of new catalysts due to their ability to be modified both structurally and in terms of composition. In particular, metal-doped carbon catalysts for ORR and mixed-metal sulfides were studied in this work. Heteroatom-doped carbons have been shown to be excellent ORR catalysts due to the interaction between the carbon and the electron density of dopant atoms. MOFs are ideal materials to create doped-carbons due to their intrinsic structure and composition. This was combined with a sacrificial tellurium template in this work to create a “pseudo-carbon nanotube” doped with zinc, cobalt, and iron, which provides excellent stability for ORR catalysis and has an E [subscript 1/2] of 0.87 V vs RHE. The best current OER catalyst is iridium oxide, a precious metal containing compound, which is not viable for large-scale application due to cost restrictions. Previous research into alternative catalysts has focused on metal oxides using first-row transition metals. Metal sulfides provide superior conductivity compared to metal oxides and are a new frontier in the search for an affordable, active, and stable OER catalyst. By combining cobalt, iron, and nickel into a MOF structure, which is then sulfurized, a mixed-metal sulfide catalyst was made, which had an onset potential of 1.65 V vs RHE and exhibited remarkable stability over the course of 24 hours.

Description

Keywords

LCSH Subject Headings

Citation