Surface Ba species effective for photoassisted NO storage over Ba-modified TiO2 photocatalysts

Abstract

HighlightsBa-modified TiO 2 photocatalysts showed high activity in photoassisted NO x storage.Modification of TiO 2 photocatalysts with Ba enhanced the photocatalytic activity.Ba loading had an significant effect on the photocatalytic activity.Ba-Ti mixed oxides were formed on a TiO 2 surface after O 2 pretreatment at 773 K.The generated Ba-Ti mixed oxides function as an effective NO x storage material.ABSTRACT Surface modification of a TiO 2 photocatalyst with Ba species was investigated in photoassisted nitrogen oxide (NO x ) storage under UV-light irradiation. The NO x storage capacity in the Ba-modified TiO 2 photocatalyst was 1.4 times higher than that of the non-modified TiO 2 photocatalyst. Structure and role of the surface Ba species on a TiO 2 surface were characterized using temperature programmed reaction (TPR), diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, X-ray diffraction (XRD), X-ray photoemission spectroscopy (XPS), and transmission electron microscopy (TEM).The characterization results suggested that Ba−Ti mixed oxides with a two-dimensional layer and amorphous structure on a TiO 2 surface were generated via decomposition of Ba(NO 3 ) 2 precursors by O 2 pretreatment at 773 K. Based on the results of the characterizations and the reactions, the generated Ba−Ti mixed oxides on a TiO 2 surface stored NO x more densely than the TiO 2 surface; therefore the generation improved the activity in the photoassisted NO x storage under UV-light irradiation.

Visible-Light-Active Plasmonic Ag–SrTiO3 Nanocomposites for the Degradation of NO in Air with High Selectivity

“…According to the equation shown in section , the NO 2 selectivity of P25 was only 12.2%, which is twice that of STO (6.3%), suggesting that STO is more advantageous in realistic conditions. Previous studies showed that barium oxide (BaO) species could function as NO x storage material to promote the photocatalytic activity of TiO 2 . , Thus, it is assumed that Sr–O in STO matrix would have the similar behavior that promotes NO x adsorption and avoids the release of NO 2 .…”

“…Perovskites are widely studied as catalysts for SCR processes, , whereas the potential ability as photocatalysts for NO x abatement is rarely focused. As an important n -type perovskite semiconductor, strontium titanate (SrTiO 3 ) has attracted lots of attention in solar H 2 production and energy conversion applications over the past years. − One of the great advantages of SrTiO 3 , in comparison with TiO 2 , is the higher conduction band position (−1.4 V vs SCE at pH 13) that drives more efficient charge transfer to electron acceptor (e.g., O 2 ), leading to enhanced photocatalytic efficiencies. , Moreover, it is expected that with the presence of strontium sites, the interaction between NO molecule and the photocatalyst would change, possibly promoting the complete conversion of NO . Nevertheless, SrTiO 3 can only be excited by light with shorter wavelength, owing to its wide band gap energy of 3.2 eV.…”

“…33,34 Moreover, it is expected that with the presence of strontium sites, the interaction between NO molecule and the photocatalyst would change, possibly promoting the complete conversion of NO. 35 Nevertheless, SrTiO 3 can only be excited by light with shorter wavelength, owing to its wide band gap energy of 3.2 eV. To endow SrTiO 3 with visible light harvesting property, substitutional doping is normally adopted due to the excellent tolerance of perovskite structure.…”

Perovskite LaFeO3-SrTiO3 composite for synergistically enhanced NO removal under visible light excitation

“…Here in this work, we adopted the latter approach to construct hierarchical LaFeO 3 -SrTiO 3 composite for photocatalytic NO abatement. SrTiO 3 was chosen firstly because it has similar crystal structure with LaFeO 3 ; secondly, SrTiO 3 with surface basic sites is advantageous for NO x adsorption and conversion [23]; and thirdly, their band edge differences might be facilitating the interfacial charge transfer. To the best of our knowledge, this is the first time to report perovskite LaFeO 3 -SrTiO 3 composites and their functional use as photocatalysts to remove NO at ppb level.…”

Alkaline-Earth Metals-Doped Pyrochlore Gd2Zr2O7 as Oxygen Conductors for Improved NO2 Sensing Performance

“…Several studies demonstrated that the incorporation of Ti cations at B sites and Nd cations at A sites resulted in the enhanced conductivity of pyrochlore-phase Gd 2 Zr 2 O 7 in the temperature range of 773–973 K 27, 28 . In this work, we studied firstly the incorporation of alkaline earth metals (Ca, Sr, and Ba) in pyrochlore-phase Gd 2 Zr 2 O 7 based on the following two core considerations: (1) Incorporation of alkaline earth metals creates more amounts of oxygen vacancy into the solid electrolyte and increases oxygen migration to facilitate the anodic reaction; (2) Alkaline earth metals serves as a dopant in view of its strong NO 2 storage capacity required for the electrochemical catalytic performance at low and moderate temperatures 29–32 , which is in favor of the enrichment of NO 2 at the interface between SE and solid electrolyte, consequently active for NO 2 sensing. And then we fabricated several amperometric-type NO 2 sensors based on the alkaline earth metals doped pyrochlore Gd 2 Zr 2 O 7 oxygen conductors with NiO as the SE and a noble metal Pt as the RE.…”