Nanoripples in graphene are powerful catalysts, even though it was predicted to be chemically inert. Their study, published in PNAS, demonstrated that nanoscale corrugations on graphene's surface accelerate hydrogen splitting as well as the best metallic-based catalysts, and this effect may be found in all 2D materials.
Nanoripples in graphene can make it a strong catalyst, contrary to general expectations that the carbon sheet is as chemically inert as the bulk graphite from which it is obtained.
The study was published this week in the Proceedings of the National Academy of Sciences (PNAS) which claims that graphene with nanoscale corrugations of its surface can expedite hydrogen splitting as well as the finest metallic-based catalysts. This unexpected effect is likely to be present in all two-dimensional materials, which are all inherently non-flat.
Researchers from China and the United States conducted a series of experiments to demonstrate that graphene's non-flatness makes it a powerful catalyst. First, they measured graphene's nanoscale corrugations using ultrasensitive gas flow measurements and Raman spectroscopy.
University of Manchester's graphene is ripped apart with dissociated hydrogen atoms on top.
The team evaluated whether this reactivity is enough to make graphene a powerful catalyst. This was in stark contrast to other known hydrogen catalysts, such as zirconia, magnesium oxide, and copper.
"Our research shows that freestanding graphene is quite different from both graphite and atomically flat graphene that are chemically extremely inert."
Prof. Geim, the lead author of the study, noted that nanoripping is naturally occurring in all atomically thin crystals; other 2D materials may also exhibit comparable enhanced reactivity, not just in hydrogen reactions.
"2D materials are most often perceived as atomically flat sheets, and the effects caused by unavoidable nanoscale corrugations have been overlooked, which has implications for the use of 2D materials."
P. Z. Sun, W. Q. Xiong, A. Bera, I. Timokhin, Z. F. Wu, A. Mishchenko, B. L. Liu, H. M. Cheng, E. Edgar, I. V. Grigorieva, and A. K. Geim, 13 March 2023, Proceedings of the National Academy of Sciences. DOI: 10.1073/pnas.2300481120