Thermostable nitrogen-doped HTiNbO5 nanosheets with a high visible-light photocatalytic activity

Abstract

Nitrogen-doped HTiNbO 5 nanosheets have been successfully synthesized by first exfoliating layered HTiNbO 5 in tetrabutylammonium hydroxide (TBAOH) to obtain HTiNbO 5 nanosheets and then heating the nanosheets with urea. The resulting samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS), UV-vis spectroscopy and N 2 adsorption-desorption measurements. It was found that N-doping resulted in a much higher thermostability of the layered structure, intrinsic bandgap narrowing and a visible light response. The doped nitrogen atoms were mainly located in the interstitial sites of TiNbO 5 -lamellae and chemically bound to hydrogen ions. Compared with N-doped HTiNbO 5 , N-doped HTiNbO 5 nanosheets had a much larger specific surface area and richer mesoporosity due to the rather loose and irregular arrangement of titanoniobate nanosheets. Both N-doped layered HTiNbO 5 and HTiNbO 5 nanosheets showed a very high visible-light photocatalytic activity for the degradation of rhodamine B (RhB) aqueous solution. Moreover, due to the considerably larger surface area, richer mesoporosity and stronger acidity, N-doped HTiNbO 5 nanosheets had an even higher activity than N-doped HTiNbO 5 , although the latter had a stronger absorption in the visible region. The dye molecules were mainly degraded to aliphatic organic compounds and partially mineralized to CO 2 and/or CO, rather than being simply decolorized. The effect of photosensitization was insignificant and RhB was degraded mainly via the typical photocatalytic reaction routes. Two different reaction routes for the photodegradation of RhB under visible light irradiation over N-doped HTiNbO 5 nanosheets have been proposed. The present method can be extended to a large number of layered metal oxides that have the characteristics of intercalation and exfoliation, thus providing new opportunities for the fabrication of highly effective and potentially practical visible-light photocatalysts.

Room‐Temperature Redox‐Active Liquid Crystals Composed of Tetraazanaphthacene Derivatives

“…Compared with the layered parent compounds, HNb 3 O 8 nanosheets obtained by exfoliation just exhibit two very weak and broad diffraction peaks. These reveal the loss of the periodic layered structure of HNb 3 O 8 , as well as long‐range ordering in the HNb 3 O 8 nanosheet materials 7. This could serve as strong evidence for the existence of HNb 3 O 8 nanosheets with single layer.…”

N-doped Na2Ti6O13@TiO2 core–shell nanobelts with exposed {1 0 1} anatase facets and enhanced visible light photocatalytic performance

“…After 12 h, the resultant suspension was transferred to a petri-dish and dried at room temperature to allow solvent evaporation. After complete evaporation of ethanol, the obtained solid sample (1.0 g) was finely milled with urea, and then the mixture was calcined in air at 500 • C for 10 h with a heating rate of 2 • C/min [39]. By changing the volume (1, 3, 6, 12, and 30 mL) of Ti(O-i-Pr) 4 and the mass (0.25, 1.0, 2.0, and 3.0 g) of urea, a series of samples with different loading amounts of TiO 2 and contents of doped N were obtained.…”

Monolayer HNb3O8 for Selective Photocatalytic Oxidation of Benzylic Alcohols with Visible Light Response

“…These reveal the loss of the periodic layered structure of HNb 3 O 8 , as well as long-range ordering in the HNb 3 O 8 nanosheet materials. [7] This could serve as strong evidence for the existence of HNb 3 O 8 nanosheets with single layer. The BET surface area of the HNb 3 O 8 nanosheets is about 86.7 m 2 g À1 , which is 45 times larger than that of layered HNb 3 O 8 (1.9 m 2 g À1 ).…”