Wettability of Nanostructured Transition-Metal Oxide (Al 2 O 3 , CeO 2 , and AlCeO 3 ) Powder Surfaces.

Wettability has been the focal point of many studies in metal oxide materials due to their applications in water-gas shift reactions, organic reactions, thermochemical water splitting, and photocatalysis. This paper presents the results of systematic experimental studies on the wettability of surfaces of nanostructured transition-metal oxides (TMOs) (Al 2 O 3 , CeO 2 , and AlCeO 3 ). The wettability of nanoparticles was investigated by measuring contact angles of different concentrations of water-based nanofluids (0.05-0.1 wt%) on the glass slide. The morphology, the heterostructure, and the nature of incorporated nanoparticles were confirmed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Characteristic diffraction patterns of the nanomaterials were evaluated using energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) techniques. The contact angles of water-Al 2 O 3 , water-CeO 2 , and water-AlCeO 3 were measured as 77.5 ± 5°, 89.8 ± 4°, and 69.2 ± 1°, respectively. This study suggests that AlCeO 3 is strongly water-wet (hydrophilic), while CeO 2 is weakly water-wet (hydrophobic). It further demonstrated that the sizes and compositions of the nanoparticles are key parameters that influence their wetting behaviors.