Non-Precious Electrocatalysts for Anion Exchange Membrane Water Electrolysis Cell

Abstract

The hydrogen has been recognized as a clean, nonpolluting and unlimited energy source that can solve fossil fuel depletion and environmental pollution problems at the same time. Water electrolysis has been the most attractive technology in a way to produce hydrogen, because it does not emit any pollutants compared to other methods such as natural gas steam reforming and coal gasification etc. In order to improve efficiency and durability of the water electrolysis, comprehensive studies for highly active and stable electrocatalysts have been performed. The platinum group metal (PGM; Pt, Ru, Pd, Rh, etc.) and its oxide catalysts showed a higher activity and stability compared with other non-precious catalysts in operating condition. It is necessary to develop non-precious catalysts with high activity and durability because the PGM catalysts are expensive materials with insufficient it’s reserves. In the water electrolysis field, the numerous researchers have been focused on the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) because the OER and HER are a key process (slow kinetics) compared with other resistances such as bubble, electrolyte, diaphragm, membrane, etc. On a point of view of a catalyst, slow kinetics and the use of precious metal (PGM) for high performance should be solved to popularize water electrolysis. The target of this study is the development of non-precious catalysts with high activity via simple and efficient synthesis method that is a wet-chemical based method. The Ni-LaCeO/C (HER catalysts) and CuCoO (OER catalyst) were synthesized through the co-precipitation with oxidation and reduction heat treatment. The catalysts were characterized by various physicochemical analyses such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). To investigate electrocatalytic properties of prepared catalysts, we carried out electrooxidation activity measurements such as cyclic voltammetry (CV), linear sweep voltammetry (LSV), long-term stability test, and electrochemical impedance spectroscopy (EIS). The relationship between their physicochemical properties and electrocatalytic activities will be explored and discussed.