Science Concentrates 2-D MATERIALS
Holey graphene With the possible exception of cheese, most materials become less valuable when they’re riddled with holes. But graphene— that wondrous carbon allotrope—goes from being a semimetallic material to a semiconducting one that’s useful for a range of applications when it’s full of perforations. Scientists have now used chemical synthesis to make graphene with nanoscale holes in precise positions, and they’ve incorporated the material into a working transistor (Science 2018, DOI: 10.1126/science.aar2009). A team led by César Moreno and Aitor Mugarza of the Catalan Institute of Nanoscience & Nanotechnology and Diego Peña of the University of Santiago de Compostela created the holey graphene starting from diphenyl-10,10'-dibromo-9,9'-bianthracene, or DP-DBBA. The researchers sublime DP-DBBA onto a gold substrate under ultrahigh vacuum, where it polymerizes at about 200 °C. Further heating to 400 °C makes the resulting polymer cyclize and dehydrogenate to form graphene nanoribbons with jagged edges. The scientists originally planned to make these ribbons as their final product. “Then serendipity contributed significantly,” Peña says. Heating the gold surface just a little higher, to 450 °C, prompted the ribbons to fuse into nanoporous graphene,
Why do chemists want quantum computers? Chemists and computer scientists are working together to make quantum computers viable tools for studying chemical systems. In the wake of IBM’s record-setting calculation of beryllium hydride’s ground state using a quantum computer last September (Nature 2017, DOI: 10.1038/ nature23879), chemists continue to increase the complexity of their simulations in hopes of putting quantum computers to use in fields like catalysis, materials science, and drug discovery. Our latest episode of Speaking of Chemistry looks into how they’re going about doing that. Watch it at cenm.ag/quantumvideo.—MANNY MORONE C&EN | CEN.ACS.ORG | APRIL 16, 2018
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he explains, “graphene with atomically precise pores uniformly distributed throughout the 2-D material.” DP-DBBA This isn’t the first time nanoporous graphene has In just a few been prepared. Scientists steps, DPhave used a top-down apDBBA becomes proach, poking holes into nanoporous graphene with a laser beam. graphene. But holes made this way tend to be too big, don’t have the desired preNanoporous graphene cision, and don’t result in a semiconductthe Swiss Federal Laboratories for Materiing material. Other kinds of nanoporous als Science & Technology, points out that graphene made via the bottom-up apan important aspect of the approach used proach of chemical synthesis have not to make the new nanoporous graphene is been reported as working in devices yet. that the pores can be tuned by using differ“In general, fabrication of electronic ent monomers. “It may thus become possidevices from nanoscale graphene strucble to create pores of a given diameter with tures is very challenging,” says Alexander specific functional groups within the pore Sinitskii, a chemist who studies graphene cavities, which may result in highly selecnanoribbons at the University of Nebrastive molecular sensors or filters,” he says. ka, Lincoln. “But this new material can be Mugarza says the group is exploring efficiently translated into devices: Three this going forward. They are also looking out of every four transistors made with to use the material in other applications, the nanoporous graphene work, which is including optoelectronics, water purifipretty impressive,” he says. “I think this cation, DNA sequencing, and gas filtering study will stimulate people to look more and sensing. “We are at the moment lookinto electronic properties of these intering for groups interested in testing our connected nanostructures.” nanoporous graphene in their research,” Roman Fasel, who works with graphene he adds.—BETHANY HALFORD nanoribbons and nanoporous graphene at
COMPUTATIONAL CHEMISTRY
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C R EDI T: C& E N /ACS P RO DU CT I O N S
Semiconductor material made via chemical synthesis and built into a device
