Electrochemical synthesis of Fe2O3 on graphene matrix for indicator-free impedimetric aptasensing

► Fe2O3 is electrochemically fabricated on graphene with controlled morphologies. ► The Fe2O3/graphene nanocomposites can improve the sensitivity of aptasensor. ► Indicator-free impedance exhibits a simple detection method for lysozyme. ► Such an electrochemical platform is demonstrated as a new way for aptasensors.