Fabrication of TiO(2)/Fe(2)O(3)/CdS systems: effects of Fe(2)O(3) and CdS content on superior photocatalytic activity

A heterostructured material of CdS and Fe(2)O(3) nanoparticle-modified TiO(2) nanotube array (NTA) photoelectrode (TiO(2)/Fe(2)O(3)/CdS) is reported in this work. TiO(2)/Fe(2)O(3) was prepared by annealing TiO(2) NTAs pre-loaded with Fe(OH)(3), which was uniformly clung to TiO(2) NTAs using sequential chemical bath deposition (S-CBD). Subsequently, CdS nanoparticles were deposited on TiO(2)/Fe(2)O(3) using the successive ion layer adsorption and reaction (SILAR) technique. Three-dimensional (3D) TiO(2)/Fe(2)O(3)/CdS samples generated a photocurrent of approximately 4.92 mA cm(−2), with a photoconversion efficiency of 4.36%, which is more than 20 times higher than that of bare TiO(2) NTAs (0.22%) and 6 times that of TiO(2)/Fe(2)O(3) (0.71%). The photocatalytic activity was evaluated by the degradation of p-nitrophenol (PNP) under visible light (λ > 420 nm). The TiO(2)/Fe(2)O(3)/CdS exhibited the best photocatalytic activity among all samples. Almost all PNP was degraded by TiO(2)/Fe(2)O(3)/CdS within 120 min. The enhancement of photocatalytic activity could be attributed to the promoted photo-induced electron and hole separation and migration on the basis of photoluminescence spectra, photocurrent measurements, and open-circuit photovoltage responses. In addition, the newly synthesized TiO(2)/Fe(2)O(3)/CdS can maintain high photocatalytic efficiency for five reuse cycles. Our findings provide a new idea for the low cost synthesis of high performance photocatalysts for the photodegradation of organic pollutants in aqueous solution.