Preparation and performance of PANI-TiO2 nanotube arrays composite electrode by in-situ microcavity polymerization

TiO2 nanotube arrays (TNTA) were firstly impregnated with ethanol solution containing aniline monomer, then the polyaniline-TiO2 nanotube arrays (PANI-TNTA) composite electrode was prepared through polymerization of aniline monomer in the microcavity of the nanotubes using ammonium persulfate (APS) as the initiator. The effects of aniline and APS concentration on the properties of the composite electrodes were studied. The electrochemical performances of the composite electrode in sodium sulfate aqueous solution and sulfuric acid aqueous solution were compared at different potential windows of -0.2-1 V and -0.2-1.8 V. Results show that the composite electrode exhibits optimal performance when the concentration of aniline and APS is 0.2 M and 0.05 M, respectively. The composite electrode has fair good electrochemical performances under various testing conditions especially in sulfuric acid aqueous solution, it has a maximum capacitance of 816.7 F g(-1), and at the enlarged potential window of -0.2-1.8 V, its energy densities are higher than those of -0.2-1 V. The composite electrode also has excellent rate and cycling properties.