Schematic illustration of the design concept for ripening-induced embedded catalysts. (Photo provided to chinadaily.com.cn)
A collaborative research team from Fudan University has achieved a breakthrough in green hydrogen production efficiency. The team's findings, published in the journal Science on Feb 14, detail the development of a novel embedded catalyst that significantly enhances the stability and performance of Proton Exchange Membrane Water Electrolyzer (PEMWE) technology, a cornerstone for generating green hydrogen.
The increasing demand for sustainable energy solutions has positioned green hydrogen as a promising energy carrier. The water electrolyzer technology, with its ability to efficiently split water into hydrogen and oxygen, plays a critical role in this domain.
However, the technology's reliance on expensive and scarce iridium-based catalysts for the oxygen evolution reaction (OER), a crucial step in the electrolysis process, has hindered its widespread adoption. The high cost and limited availability of iridium, coupled with the suboptimal performance of existing iridium-based catalysts, have posed significant challenges to the large-scale deployment of the water electrolyzer technology systems.
Addressing these limitations, the Fudan team, led by Zhang Bo, Xu Yifei, Duan Sai and Xu Xin, devised an innovative embedded catalyst design that enhances OER efficiency while minimizing the use of iridium.
The team employed a novel synthesis method they term "ripening-induced embedding", drawing inspiration from the structure of teeth embedded in gums. This method facilitates the embedding of iridium oxide nanoparticles, the key catalyst material, within a cerium oxide support, akin to the teeth anchoring in gums.
Advanced characterization techniques played a pivotal role in understanding and optimizing the catalyst's growth process. By utilizing cryo-transmission electron microscopy (CryoTEM) and cryo-electron tomography (CryoET), researchers could visually track the growth and embedding of iridium oxide nanoparticles within the cerium oxide support, capturing the real-time dynamics of the synthesis process.
The insights gained from these imaging techniques, combined with theoretical calculations using all-atom kinetic Monte Carlo (KMC) simulations, revealed the effectiveness of ultrasonic and heating treatments in accelerating the growth rate of the support material.
This precise control over both the support and catalyst growth rates proved crucial in achieving the optimal embedding of iridium oxide nanoparticles, ensuring their stability and preventing detachment during electrolysis.
The meticulous design ensured the optimal embedding of iridium oxide within the cerium oxide support and yielded a highly stable and efficient catalyst. Rigorous testing under the water electrolyzer technology operating conditions for an extended period of 6,000 hours demonstrated the catalyst's exceptional durability. It exhibited minimal voltage decay and maintained high activity, surpassing international performance standards.
Commenting on the significance of the breakthrough, Professor Zhang said, "Our findings mark a significant step towards commercially viable green hydrogen production. This catalyst design not only addresses the limitations of existing catalysts but also paves the way for the development of more cost-effective and efficient the water electrolyzer technology systems."
The team's research, backed by the National Natural Science Foundation of China and other key funding initiatives, holds substantial promise for the future of green hydrogen production.
Their plans include refining the catalyst research, exploring other cost-effective materials, and collaborating with industrial partners to accelerate the technology's commercialization and contribute to China's carbon neutrality goals.
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