Influence of Nb2O5 crystal structure on photocatalytic efficiency

Fast synthesis of NaNbO3 nanoparticles with high photocatalytic activity for degradation of organic dyes

“…It is known that the greater the surface area of ​​the catalyst, the greater the probability of available and accessible active sites and also dye adsorption sites. 13,58 As shown in Section 3.1, the sample treated at 600°C showed a deviation in the diffraction peaks, possibly caused by the diffusion of sodium ions in the lattice. When this occurs, the material reduces its surface area to reduce free energy caused by the tension in the lattice.…”

Alumina Coatings Containing Niobium Pentoxide Polymorphs Prepared by Plasma Electrolytic Oxidation of Aluminum

“…In the present case, we cannot assure that this was the cause of the formation of a mixture of crystalline T‐Nb 2 O 5 and H‐Nb 2 O 5 . Nevertheless, several studies connect the presence of T‐Nb 2 O 5 to an increase in photocatalytic activity, depicting results for RhB, [ 59 ] methyl blue (MB), [ 58 ] methyl orange (MO), [ 64 ] and fluoxetine (FLX) [ 65 ] above 40% of the photodegradation.…”

“…Among the three most studied polymorphs, there are the pseudohexagonal phase (TT), with the crystallographic transition observed at 500 °C, the orthorhombic phase (T), where the phase transition is observed in the range of 600-800 °C, and the monoclinic phase (H) observed in temperature >1000 °C, which is considered the most ease to obtain and with good stability. [1,[57][58][59] The thermodynamically Nb 2 O 5 stable form in the Nb-O system presents a solid with white color and may crystallize in different polymorphs such as tetragonal, hexagonal, monoclinic, and orthorhombic forms. [57] Although the most studied, familiar, and stable phase is the monoclinic phase, the orthorhombic phase, which depicts the hkl reflection planes (most intense peaks) in 2θ 22.607°and 28.309°(JCPDS 27-1003) or 28.401°( JCPDS 30-0873), can be found in Nb 2 O 5 anodic films.…”

Calcination-Free Synthesis of Porous Metal Oxides/Carbon from Calcium Carbide by Ball Milling

“…If the ball milling resultants were washed by water directly, the CaC 2 hydrolyzation and the precipitation of metal hydroxides might proceed simultaneously, thus leading to the amorphous phase of the desiccated samples (Figure S3). In fact, the decomposition and crystallization temperatures were as high as 500°C for Nb­(OH) 5 , and the crystallization of Hf­(OH) 4 to HfO 2 happened after a long-time hydrothermal treatment . Nevertheless, if the ball milling resultants were washed with ethanol first to remove the excess NbCl 5 , HfCl 4 , and CaC 2 , followed by water washing, the hexagonal primitive Nb 2 O 5 (PDF#28-0317) was observed for Nb 2 O 5 /C (Figure a), characterized by the peaks of (001), (100), (101), (110), (111), and (200) crystal faces at 22.6, 28.6, 36.7, 50.7, 56.1, and 59.0° .…”