Amorphous-crystalline transition-driven synthesis of Co single-atom catalysts on MoO₃ for enhanced hydrogen evolution in acidic and alkaline media

Single atom catalysts (SACs) dispersed in metal oxide supports offer not only maximized catalyst utilization but also extended modulation capabilities through interactions between the SA and its support. However, achieving facile preparation and ensuring electrochemical durability of such SACs, particularly for hydrogen evolution reaction (HER) applications, remain formidable challenges. Our study addresses these issues by employing an amorphous-to-crystalline phase transition in MoO₃ to synthesize a cobalt (Co) SA catalyst. This method facilitates the production of highly selective SA catalysts at low temperatures and ensures their enhanced stability in HER applications. The Co SA MoO₃ catalyst exhibits superior performance in HER, operating effectively in both acidic and alkaline environments. Significantly, it maintains stable HER activity across these diverse electrolytic conditions. Our Density Functional Theory (DFT) calculations provide insights into the exceptional HER performance of Co SA MoO₃. These calculations reveal that the strong affinity for hydrogen and water, facilitated by the modulation of the p-band orbitals at specific oxygen sites adjacent to the Co SA, establishes a thermoneutral pathway for HER. This study represents a pivotal advancement, showcasing a highly practical and robust single-atom catalyst, marking a significant stride towards sustainable energy solutions.