Unidirectionally aligned diphenylalanine nanotube/microtube arrays with excellent supercapacitive performance

High-temperature (150-220 degrees C) growth leads to the formation of some peptide nanotube/microtube (NT/MT) arrays but the NTs/MTs exhibit closed ends, irreversible phase modification and eliminations of piezoelectric and hydrophilic properties. Here we demonstrate the fabrication of unidirectionally aligned and stable diphenylalanine NT/MT arrays with centimeter scale area at room temperature by utilizing an external electric field. The interactions between the applied electric field and dipolar electric field on the NTs and surface positive charges are responsible for the formation. The unidirectionally aligned MT array exhibits a supercapacitance of 1,000 mu F.cm(-2) at a scanning rate of 50 mV.s(-1); this is much larger than the values reported previously in peptide NT/MT arrays.