Researchers created a metal-free, light-driven material that can degrade many persistent water pollutants, including PFAS. The hybrid surface combines a covalent organic framework (COF) — a porous, high-surface-area material suited for photocatalysis — with a two-dimensional hexagonal boron nitride (hBN) film. Growing the COF directly onto the hBN produced a connected structure in which charges can move without becoming trapped.
The team used defect engineering to join the normally hard-to-combine materials: they etched microscopic scratches into the hBN so the COF could anchor and grow on top. At the interface, light-energized electrons and holes are driven in different directions, enabling chemical reactions that break down pollutants.
To assess practical performance, the researchers ran tests in vertical and horizontal flowing-water reactors that mirror setups used in water treatment facilities. The material worked consistently through repeated cleaning cycles and kept its structure and stability. The work, led by researchers at Rice with contributors from the University of Florida, was supported by the National Science Foundation, the Air Force Research Laboratory RISING Center at Rice, and the Welch Foundation. The authors take responsibility for the content and it does not necessarily reflect the official views of the funders.
Difficult words
- degrade — to break down into smaller chemical parts
- persistent — continuing to exist or last a long time
- covalent organic framework — porous material built from linked organic molecules
- photocatalysis — use of light to drive chemical reactions
- hexagonal boron nitride — a two dimensional ceramic material with hexagonal structure
- defect engineering — introducing controlled flaws to change material behavior
- interface — the boundary where two materials or phases meet
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Discussion questions
- What advantages could a metal-free, light-driven material offer for municipal water treatment systems?
- What practical challenges might engineers face when using defect engineering to produce this hybrid material at large scale?
- Why is it important that the material kept its structure and stability through repeated cleaning cycles? Give reasons.
