A Study on the Improvement of Water Splitting Performance of Transition Metal-Based Electrocatalysts

Abstract

Hydrogen energy is attracting attention not only due to its various applications but also because it is a green and sustainable energy source. Water splitting is an efficient method for producing hydrogen. Therefore, identifying suitable electrocatalysts for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) in the water splitting process is essential. Despite the effectiveness of noble metal-based electrocatalysts, their high cost and scarcity pose significant challenges. Hence, there is a critical need for active, stable, and cost-effective electrocatalysts for water splitting. Driven by this challenge, this study focused on improving transition metal-based electrocatalysts for water splitting applications, with a particular emphasis on reducing costs and enhancing sustainability compared to noble metal-based electrocatalysts. Through various methodologies, including the optimization of activity and stability in both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), significant progress was made. We synthesized heterostructure catalysts, combining multiple components to leverage synergistic effects and overcome individual limitations. Furthermore, we explored depositing active component catalysts onto supported two-dimensional (2D) materials to enhance catalytic activity, stability, and mass transport properties. Additionally, modulation of electronic structures was investigated by introducing rare element-based materials as promoter components to enhance electrocatalyst activity and stability. Moreover, we investigated the benefits of atomic geometries of the compounds containing anion phosphate group and cation transition metals. The flexible coordination of this anion and the various oxidation states of transition metal can stabilize the intermediates in water splitting reactions, facilitating favorable adsorption and oxidation of water molecules. These findings collectively demonstrate promising advancements in transition metal- based electrocatalysts for water splitting, highlighting their potential for widespread adoption in green hydrogen technologies. Through cost-effective and sustainable approaches, this research contributes to the advancement of efficient and scalable methods for hydrogen production.