Scientists use light to destroy forever chemicals in water

A team at Rice University has created a material that does something remarkably simple: it uses sunlight to break down the chemicals we can't get rid of any other way.

Those chemicals are called PFAS—per- and polyfluoroalkyl substances—and they're in our water, our blood, our soil. They don't degrade naturally, which is why they earned the nickname "forever chemicals." They're in non-stick cookware, water-resistant fabrics, firefighting foam. Useful stuff, but also a problem we've been stuck with.

The new material works by combining two things: a porous framework called a covalent organic framework (COF) and a thin film of hexagonal boron nitride. When light hits the COF, it knocks electrons loose, creating charged gaps. These gaps are what actually do the work—they tear apart the molecular bonds in PFAS and other stubborn pollutants like pharmaceutical waste and synthetic dyes.

The tricky part was getting these two materials to stick together. They don't naturally bond well. So the Rice team used what's called "defect engineering"—deliberately scratching microscopic imperfections into the boron nitride surface. Those tiny flaws became the anchor points where the COF could attach and grow. It sounds counterintuitive: you make something imperfect to make it work better. But by creating those defects, they also created a pathway for electrons and holes to move in opposite directions, which amplifies the cleansing effect.

"By growing them directly together rather than simply mixing them, we created a connected structure where charges could travel easily without getting trapped," says Yifan Zhu, the postdoctoral researcher who led the work. The approach had never been tried before with this particular pair of materials, partly because boron nitride is notoriously difficult to modify.

Testing in the Real World

What matters isn't just that it works in the lab—it's that it works where water actually gets treated. The team tested their material in reactors that mimic how water treatment facilities operate, with water flowing vertically and horizontally through the system. The material held up. It stayed stable across repeated cycles, maintaining its structure and its ability to break down pollutants.

There's no metal involved, which means nothing toxic leaches into the water as a byproduct. Just light, a safe material, and chemistry that finally breaks the bonds in chemicals designed never to break.

This doesn't solve the PFAS problem overnight. But it points toward something practical—a low-cost, metal-free way to actually remove these chemicals from water instead of just moving them around. For communities dealing with contaminated groundwater or industrial facilities needing to clean their discharge, that's a real shift.