Novel two-step vapor-phase synthesis of UV-Vis light active FeO/WO nanocomposites for phenol degradation.

Supported FeO/WO nanocomposites were fabricated by an original vapor phase approach, involving the chemical vapor deposition (CVD) of FeO on Ti sheets and the subsequent radio frequency (RF)-sputtering of WO. Particular attention was dedicated to the control of the W/Fe ratio, in order to tailor the composition of the resulting materials. The target systems were analyzed by the joint use of complementary techniques, that is, X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), energy dispersive X-ray spectroscopy (EDXS), X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS), and optical absorption spectroscopy. The results showed the uniform decoration of α-FeO (hematite) globular particles by tiny WO aggregates, whose content could be controlled by modulations of the sole sputtering time. The photocatalytic degradation of phenol in the liquid phase was selected as a test reaction for a preliminary investigation of the system behavior in wastewater treatment applications. The system activity under both UV and Vis light illumination may open doors for further material optimization in view of real-world end-uses.