The preparation and properties of carbon inverse opal papers using carbon fiber sheets as a framework

Carbon inverse opal monoliths store energy, sense small molecules, and catalyse reactions, but can be limited by their rigid form because it prevents the mechanical flexure that would be needed to embed this material within devices that bend during use. We report a method that uses carbon fiber papers to impart partial mechanical flexibility and greater electronic conductivity to carbon inverse opals. Our approach deposits colloidal crystals between the fibers in carbon fiber paper and uses the colloidal crystal templates to form inverse opal carbon from phenolic resin. The resulting carbon inverse opal papers (CIOPs) comprise both three-dimensionally interconnected macropores and aperiodic meso- and micropores, the combination of which establishes hundreds of square meters of interfacial area per gram that can store and discharge electrochemical capacitance while planar, while flexed around radii of curvature as small as 5 mm, and after 150 reversible flexures. Carbon inverse opal papers offer at least 3 times greater electronic conductivity than reported carbon inverse opals because the network of carbon fibers doubly serves as pliable framework and conductive conduit. Carbon fiber papers enable carbon inverse opals to store electrochemical energy during and after mechanical flexure.