Graphene and black phosphorus get tough

Graphene-based materials are some of the toughest composites scientists have made. Qunfeng Cheng of Beihang University wanted to know if he could make them even tougher—both stronger and more flexible—to better withstand being used as flexible electrodes in supercapacitors, for example. His team’s approach was to combine two popular 2-D materials. They brought graphene together with black phosophorus to make a composite with record-high toughness—about 1.5 times that of the next-closest graphene composite that Cheng’s team compared it against (Proc. Natl. Acad. Sci. 2020, DOI: 10.1073/pnas.1916610117). The researchers used a supramolecular linker made from 1-aminopyrene and disuccinimidyl suberate to promote stacking and alignment between graphene oxide nanosheets routinely used to make graphene composites. Adding black phosphorus creates covalent bonds, further promoting alignment and strengthening the composite. And black phosphorus acts as a built-in lubricant that helps the material flex more before it fails. The net result is a film with “extreme toughness,” says Duke University materials scientist L. Cate Brinson, who adds that the composite’s high electrical conductivity makes it a multifunctional material.