Co-sensitization of TiO2 nanotube arrays with polymerized aromatic amines and its application in photoelectrochemical cathodic protection

In this work, an initiator-free polymerization of 4,4′-diaminobiphenyl (DABP) happened on the TiO 2 nanotube arrays (TNT/Ti) via a facile in-situ solvothermal synthesis method. The poly-4,4′-diaminobiphenyl (PDABP) modified TNT/Ti (PDABP/TNT/Ti) composite was fully characterized by SEM, XRD, FTIR, and XPS. The prepared PDABP/TNT/Ti exhibited stronger visible light absorption, improved separation of photogenerated charge carriers, reduced charge transfer resistance at the interface, and enhanced reducing capability of photoelectrons (as indicated by the more negative energy level of the conduction band, E CB ). Attributed to the formation of the type II heterostructure between TiO 2 and PDABP, the PDABP/TNT/Ti showed enhanced photoelectrochemical (PEC) cathodic performance by polarizing the potential of 304 stainless steel (304SS) to ∼−900 mV in a 3.5 wt% NaCl. By replacing monomers, the strategy of enhancing the PEC cathodic protection performance of TNT/Ti using electrically conducting polymers of aromatic amines was confirmed to be simple and effective.