Fe2O3/CdS co-sensitized titania nanotube for hydrogen generation from photocatalytic splitting water

Abstract CdS, Fe 2 O 3 -sensitized and Fe 2 O 3 /CdS co-sensitized TiO 2 nanotube arrays (TNA) were fabricated by depositing CdS and Fe 2 O 3 nanoparticles onto the surface of TNA via an ultrasonic-assisted chemical bath deposition (CBD) method. Their effects on the photocatalytic properties and hydrogen generation rate were evaluated. The results show that CdS-sensitized and Fe 2 O 3 /CdS co-sensitized TNA have good absorption on long wavelength region and exhibit much higher hydrogen generation rates than those of other TNA specimens. The hydrogen generation rates for TNA-Fe 2 O 3 /CdS and TNA-CdS/Fe 2 O 3 were 12 and 1.54 ml cm −2  h −1 , respectively, where the TNA-Fe 2 O 3 /CdS refers to the deposition of Fe 2 O 3 first on TNA and CdS the second, CdS being the out surface materials and contacting water. TNA-CdS/Fe 2 O 3 is a reversed structure of TNA-Fe 2 O 3 /CdS. The rate of hydrogen generation for TNA-Fe 2 O 3 /CdS was five times higher than that of blank TNA (2.43 ml⋅cm −2  h −1 ). It is considered that the low efficiency of TNA-CdS/Fe 2 O 3 is due to a disadvantageous energy band structure for electrons and holes transition. TNA-Fe 2 O 3 /CdS has a stepwise energy band structure and the transition of excited electrons and holes is straightforward, while those of TNA-CdS/Fe 2 O 3 has a difficult transition process due to a reverse structure.