Ankit Kumar Verma

In Silico Investigation of Molybdenum Oxide as a Potential Catalyst for Electrochemical Oxygen Evolution

Hydrogen (H2) has emerged as a promising alternative to fossil fuels. Its applications extend far beyond fuel cells, encompassing many industries such as fertilizer manufacturing, metal processing, and steam reforming. However, efficiently producing green and clean H2 at a commercial scale to meet the growing demand represents a crucial challenge. The electrochemical water-splitting method offers a promising way of enabling the conversion of renewable electricity into H2, thereby facilitating effective energy storage and conversion. The hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are fundamental half-cell reactions involved in water splitting. Notably, the OER exhibits kinetically sluggishness due to the presence of four proton-coupled electron transfer steps, which hinder both the advancement and scalability of water-splitting technology. Developing and exploring stable, economically viable, and highly efficient catalysts for the OER beyond the conventional iridium and ruthenium-based oxide catalysts is of utmost significance in generating environmentally friendly H2. Therefore, our work focused on exploring transition metal-based catalysts that could serve as viable alternatives to Ru, and Ir-based catalysts in terms of cost, activity, and stability. Specifically, we present our findings on molybdenum oxide (MoO3) and doped MoO3 catalysts for the OER. Density functional theory is utilized to analyze the energetics of intermediates in the OER mechanism. This approach allowed us to identify the most favorable active site and dopant that can significantly enhance the OER activity of MoO3. Among all the explored dopants (iron, nickel, manganese, and cobalt) and active sites (symmetric oxygen, asymmetric oxygen, terminal oxygen, and metal), the Co-doped MoO3 catalyst demonstrated the highest OER activity at the symmetric oxygen active site. The findings are rationalized using oxidation state changes at the active transition metal centers. Our research primarily centers on using computational methods to explore innovative materials for enhancing the water-splitting technique, ultimately leading to cleaner hydrogen generation.