Preparation of polypyrrole sensitized TiO2 nanotube arrays hybrids for efficient photoelectrochemical water splitting

• PPy-TNTs photoanode is prepared by anodization and electropolymerization.
• Deposited amount of PPy on TNTs is tuned by electropolymerization time.
• PPy acts as visible light sensitizer for expanding light absorption range.
• PPy-TNTs exhibit significantly enhanced PEC water splitting performance.

Stable polypyrrole-TiO2 nanotube arrays hybrids (PPy-TNTs) have been prepared by facile anodization and potentiostatic polymerization methods. The morphology and structure of PPy-TNTs are characterized by SEM, XRD, XPS. The amount of deposited PPy can be easily adjusted by electropolymerization time. UV–vis diffuse reflection spectra show that the polypyrrole can act as visible-light photosensitizer and the electrochemical impedance spectra suggest that the formed p-n junctions between PPy and TNTs can facilitate the charge separation and transfer. The photocurrent density of PPy-TNTs under simulated solar illumination (AM1.5, 100 mW/cm2) is about 2.5 times compared with that of pristine TNTs. Incident photon to current conversion efficiency (IPCE) spectrum of PPy-TNTs increases in UV and visible light region. Moreover, The PPy-TNTs hybrids show much higher photoelectrochemical stability than the pure TNTs.