Researchers at the Chinese Academy of Sciences have engineered a light-driven micromotor capable of navigating water and actively capturing uranium ions, marking a step forward in advanced materials for resource extraction. 

Developed at its Qinghai Institute of Salt Lakes, the system is based on a metal-organic framework (MOF) that converts light into motion, allowing it to function as a self-propelling collector at the microscale. 

Uranium remains the critical fuel for nuclear reactors, and despite an estimated 4.5 billion tonnes dissolved in seawater, its extremely low concentration has long made extraction technically complex and economically unviable.

Beijing looks to ocean-based solutions to secure nuclear fuel supply 

As China accelerates the build-out of its nuclear energy capacity, securing a stable uranium supply has become a strategic priority, particularly given its continued reliance on imports. This dependency adds urgency to efforts aimed at alternative extraction methods, including those that tap into ocean-based resources. 

According to Yongquan Zhou, who leads the research team, prior work on light-driven micromotors has largely stopped short of targeting uranium specifically. He noted that while the underlying technology is not new, its application to uranium extraction remains relatively unexplored, the South China Morning Post reported.

At the microscale, the team fabricated porous, sponge-like particles roughly 2 micrometres in diameter, significantly thinner than a human hair, and tuned their internal chemistry to maintain long-term stability in aqueous environments. These particles function as micromotors: when exposed to small amounts of hydrogen peroxide, they generate propulsion and move through water at speeds of about 7 micrometres per second, enabling active navigation rather than passive diffusion.

When exposed to light, the particles accelerate, nearly doubling their speed and gaining a solar-powered boost. In laboratory tests, they showed high efficiency in extracting uranium from water, capturing up to 406 milligrams per gram. The uranium is then converted into a stable mineralised form, making it easier to separate and safely store.

Departing from conventional adsorbents that rely on passive contact, the new system actively navigates through water to locate and capture uranium ions. As Zhou explained, the micromotor operates autonomously rather than remaining fixed in place. Powered by light, it can move on its own, offering a more energy-efficient and environmentally friendly approach compared with traditional, stationary materials.

In controlled experiments, the researchers documented emergent behaviors that mirror biological predator–prey dynamics. When active micromotors were combined with passive colloidal particles, the system displayed patterns akin to “hunting”, “escape” and coordinated swarm motion, with these interactions shifting in response to changes in fuel concentration.

Much of the experimental work was led by Ikram Muhammad, with Zhou noting that the underlying concept could be extended to recover other strategic elements such as rubidium and caesium. While the early results are promising, Zhou stressed that the technology is still in its infancy and faces significant scalability challenges. 

High-salinity environments, such as salt lakes, currently limit the micromotors’ operation. The Chinese scientist added that further refinement is ongoing, emphasizing that translating the system into real-world applications will require sustained research and engineering improvements.