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Innovative Catalyst Structure Paves the Way for Affordable Hydrogen Production

Recent advancements in catalyst design present a promising approach to more economical hydrogen production through water electrolysis. This advancement involves a mesoporous single-crystalline Co3O4 catalyst that is enhanced with atomically dispersed iridium (Ir), specifically optimized for the acidic oxygen evolution reaction (OER).

Iridium is renowned for its exceptional performance in OER; however, its scarcity and high cost pose significant barriers to widespread application. A critical hurdle in scaling up electrolyzer technology is finding ways to efficiently utilize Ir while ensuring the catalyst’s stability. The study introduces a novel material that aims to maximize the efficiency of Ir at the atomic level.

The catalyst is characterized by a mesoporous spinel structure that accommodates a high loading of Ir (13.8 wt%) while preventing the formation of larger Ir clusters. This unique configuration fosters the creation of Co-Ir bridge sites, which are demonstrated to exhibit high intrinsic activity in acidic OER environments.

Through computational studies, it was determined that, under reaction conditions, the Co3O4 surfaces become covered with oxygen intermediates (O*), a process that typically leads to the passivation of cobalt sites. However, the introduction of Ir rejuvenates these sites and concurrently boosts the structural robustness of the catalyst.

The research indicates that leaching of both Ir and Co during the reaction process was significantly minimized. When compared to standard Ir/Co3O4 catalysts, losses of Ir and Co were decreased to approximately one-fourth and one-fifth, respectively. Notably, the catalyst maintained its performance for more than 100 hours, achieving an overpotential (η₁₀) of only 248 mV.

“The unique mesoporous structure is essential,” states Professor Hao Li, the principal investigator of the research. “It not only allows for single-atom Ir loading but also fosters a stable environment conducive to catalytic activity.”

This groundbreaking research harmonizes experimental insights with computational modeling, and the central findings are accessible via the Digital Catalysis Platform (www.digcat.org), a digital resource established by the Hao Li Lab to aid in catalyst discovery and development.

Supported by the Tohoku University Support Program, this research sets the foundation for future explorations aimed at optimizing doping levels, scaling up the synthesis of the catalyst, and assessing its integration into commercial electrolyzer systems.

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