image: This illustration depicts dioxygen-bridged cobalt dual-atom sites embedded in hierarchically porous carbon nanospheres, enabling highly efficient four-electron oxygen reduction electrocatalysis via a side-on adsorption mechanism.
Credit: ©Science Bulletin
Efficient oxygen electrocatalysis is crucial for next-generation energy technologies such as fuel cells and metal-air batteries. However, the oxygen reduction reaction (ORR), a key process in these systems, typically suffers from sluggish kinetics that limit overall energy efficiency. Although platinum-based catalysts can accelerate the ORR, their high cost and limited availability hinder large-scale deployment.
To address this challenge, a research team from Wuhan Textile University and Nanyang Technological University has developed a cobalt-based dual-atom catalyst that significantly enhances ORR performance while avoiding the use of precious metals.
A new dual-atom catalyst design
The catalyst contains dioxygen-bridged cobalt dual-atom sites embedded within hierarchically porous carbon nanospheres, forming a material termed Co-O2-Co/HPCN. This structure is synthesized via a molecular precursor strategy that enables precise control over atomic coordination and dispersion. Unlike conventional single-atom catalysts, the new material features pairs of cobalt atoms bridged by oxygen atoms, enabling cooperative electronic interactions between neighboring metal centers. This configuration improves the adsorption and activation of oxygen molecules during catalysis. Meanwhile, the hierarchically porous carbon framework further enhances catalytic performance by providing interconnected micro- and mesopores that facilitate oxygen diffusion and expose abundant active sites.
ORR catalytic efficiency
Electrochemical measurements show that Co-O2-Co/HPCN delivers remarkable catalytic activity. The catalyst achieves an onset potential of 1.016 V and a half-wave potential of 0.916 V, both surpassing those of commercial Pt/C catalysts. In addition, it retains 96.6% of its initial current after 35,000 seconds of continuous operation, demonstrating excellent durability.
High-performance zinc-air batteries
The catalyst was further evaluated in zinc-air batteries, where it demonstrated outstanding energy performance. The device achieved a peak power density of 192 mW cm−2 and a specific capacity of 802 mAh gZn−1, outperforming platinum-based systems. Moreover, the battery exhibits exceptional long-term durability, sustaining stable performance for over 120 h at 10 mA cm−2 without noticeable voltage decay. Beyond conventional aqueous batteries, the team also demonstrated flexible quasi-solid-state zinc-air batteries using the new catalyst. These flexible devices maintained stable performance under bending and twisting conditions and were able to power LED panels, highlighting their potential for wearable electronics.
Understanding the catalytic mechanism
To understand the origin of the enhanced catalytic activity, the researchers combined theoretical simulations with in situ spectroscopic analysis. The results revealed that the dual-atom cobalt sites promote a side-on adsorption configuration of oxygen molecules, which stabilizes key reaction intermediates and breaks the traditional scaling relationship governing ORR catalysis. This mechanism effectively lowers the reaction energy barrier and accelerates the oxygen reduction process.
The researchers believe that this work provides a new strategy for designing high-performance dual-atom catalysts and could contribute to the development of sustainable energy technologies based on earth-abundant materials.