The team utilized microwave plasma chemical vapor deposition (MPCVD) to fabricate diamond coatings, introducing methane and hydrogen gases into a chamber and generating carbon atoms that formed a diamond layer on a silicon wafer. By adjusting the surface chemistry during postgrowth, they tested how these changes affect mineral scale formation.
A nitrogen-terminated diamond variant exhibited superior resistance to scaling, accumulating over an order of magnitude less deposit compared to surfaces with oxygen, hydrogen, or fluorine terminations. Microscopy revealed only scattered mineral clusters on the nitrogen-treated diamond, whereas other variants showed dense scale layers.
Molecular simulations provided insight into the mechanism. Nitrogen modification promoted the creation of a tightly bound water layer on the diamond surface, which acts as a barrier to mineral ion attachment and scale buildup.
The study also confirmed that boron-doped diamond electrodes can be similarly treated, resulting in a sevenfold reduction in scaling while maintaining performance.
Xiang Zhang, assistant research professor and first author, stated, "Because of these limitations, there is growing interest in materials that can naturally resist scale formation without constant intervention. Our work addresses this urgent need by identifying a coating material that can 'stay clean' on its own."
Pulickel Ajayan, professor and corresponding author, noted, "These findings identify vapor-grown, cost-effective, polycrystalline diamond films as a powerful, long-lasting anti-scaling material with broad potential across water desalination, energy systems and other industries where mineral buildup is a problem."
Jun Lou, professor and corresponding author, added, "The scalable and versatile deposition process of the coating also makes it very attractive for various industry sectors."
Research Report:Nitrogen-Terminated Diamond Films for Anti-Scaling Coatings
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