Highly efficient polypyrrole sensitized TiO2 nanotube films for photocathodic protection of Q235 carbon steel

•PPy/TNAs hybrid film is prepared by electrochemical method.•The effect of electropolymerisation time on the performance of film is compared.•PPy/TNAs show excellent photocathodic protection ability for Q235 carbon steel.•PPy plays a role in photosensitization, electron pool and hetero-junction formation.