Non-Precious-Metal-based Oxygen Evolution Electrocatalysts for Anion Exchange Membrane Water Electrolysis

Abstract

Renewable energy resource-driven hydrogen(H2) production via water electrolysis provides a promising way to achieve a sustainable energy future with zero carbon emission in the environment. However, the sluggish and energy-intensive anodic oxygen-evolution reaction remains a significant roadblock to the economic feasibility of such systems. Hydrogen, a carbon-free versatile energy carrier, has generated a great deal of interest in searching for alternative fuel for future energy needs due to its high specific energy density. In this context, water electrolysis is considered a promising method for practical H2 production with zero impact on the environment. However, the shortage of sustainable and cost-effective water electrolyzers restricts the commercialization of hydrogen-based energy conversion/storage technologies, especially for the transport and industrial sector. Hence, studies in this research were aimed at developing non-precious metal electrocatalysts and designing an optimum electrolyte/electrode interface for water oxidation at a much faster rate than existing water electrolyzers. The research is detailed in this doctoral dissertation is organized into several chapters:

Chapter 1 discusses the fundamentals of water oxidation reactions, factors considering while fabricating the oxygen evolution reaction (OER) electrode materials, and also illustrates the advantages and disadvantages of existing water electrolyzers for practical H2 production.

Chapter 2 comprehensively reviews research works published on the Ni-based electrocatalysts for water oxidation. In chapter 3, we describe the synthesis of graphene nanoplatelet supported-NiFe-based metal-organic frameworks for OER using trimesic acid as an organic ligand and further describe its application as a high-efficient and ultra-durable O2 evolution electrode for water-fed alkaline anion exchange membrane water electrolyzer(AEMWE). Most importantly, Chapter 3 deals with a break-through membrane electrode assembly (MEA) fabrication strategy that we introduced to achieve a highly durable AEMWE for large-scale H2 production. In Chapter 4, we report the fabrication of energy-efficient and durable ultra-pure water-fed AEMWE using the Ni/NiXFe1-XOOH catalyst prepared through the electrodeposition method for practical H2 production. The water-fed AEMWE fabricated with Ni/NixFe1-xOOH/CFP anode exhibits high electrolyzer efficiency, which outperforms so far reported advanced OER catalysts. These findings highlight the cost-effective fabrication of high-efficient OER catalysts and represent a significant advancement in the utilization of NixFe1-xOOH based catalysts for commercial applications.