Decoding d-Band Effects: Impact of Diverse Environments on Cobalt's Catalytic Performance in Oxygen Reduction Reaction

Abstract

The oxygen reduction reaction (ORR) is a pivotal process in energy transformation technologies such as fuel cells and metal–air batteries. Despite their efficiency, the widespread adoption of these technologies is hindered by the high cost and shortage of precious metal catalysts. Cobalt, with its intrinsic catalytic activity, cost-effectiveness, and abundance, has emerged as a promising alternative. This review explores the advancements in cobalt-based catalysts, focusing on the adjustment of their d-band center (ε_d), a vital factor influencing catalytic activity. By tailoring the electronic structure through strategies such as nitrogen doping, alloying with transition metals, and surface engineering, significant improvements in ORR efficiency and stability have been achieved. Insights from density functional theory (DFT) have been instrumental in elucidating the relationship between the ε_d and the adsorption/desorption dynamics of oxygen intermediates. This study highlights the synergistic effects of cobalt with other elements, which enhance electron transfer and optimize binding energies, achieving near-ideal catalytic performance. Furthermore, the review features the challenges of translating these materials to practical applications, emphasizing the need for scalable synthesis methods, enhanced durability, and environmentally sustainable practices. These findings establish cobalt-based catalysts as high-performance alternatives to precious metals, paving the way for their integration into next-generation energy systems.