Effect of Plasma Processing Gas Composition on the Nitrogen-Doping Status and Visible Light Photocatalysis of TiO₂

Abstract

The atmospheric pressure plasma enhanced nanoparticle synthesis (APPENS) process is applied to produce nitrogen (N) doped titania (TiO2) photocatalysts. With TTIP (titanium tetraisopropoxide; Ti(OC3H7)4) and water vapors as precursors, the effect of plasma and annealing gas composition on the N-doping status is identified by a cross comparison of the chemical shift of N atoms with those of Ti and O atoms. The activities of various types of N-doped photocatalysts are evaluated via the conversion of isopropyl alcohol (IPA). The results show that the N-doped TiO2 particles with O X −Ti−N Y and −(NO) dopants are produced via N2 plasma gas followed by air or N2 annealing gases. They have better visible and UV photocatalytic activities compared to the pure TiO2 photocatalysts prepared under O2/Ar plasma and annealing gases. On the other hand, the N-doped TiO2 photocatalyst produced under N2/O2/Ar plasma gas and then annealed with pure N2 gas tends to have an additional dopant of −(NO2), but its photocatalytic activity is even worse than those of the pure TiO2 photocatalysts. The results reveal that the O X −Ti−N Y and −(NO) dopants may have positive effects on the visible light photocatalytic activity while the −(NO2) dopant tends to have a negative effect on the visible light photocatalytic activity.

In-situ regeneration of Au nanocatalysts by atmospheric-pressure air plasma: Significant contribution of water vapor

“…In N 1s spectra, the peaks at 399.4 eV assigned to the molecularly chemisorbed ␥-N 2 37 were all observed for the four samples. However, only the regenerated sample by dry plasma appeared a new peak at 406.6 eV, which derives from the formation of [NO y ] s on catalyst surface [24,50]. This indicates that the humid plasma could avoid the formation of poisoning species [NO y ] s in comparison with the dry plasma, which is in good line with the FT-IR and UV-vis spectra results.…”

Solvothermal-induced phase transition and visible photocatalytic activity of nitrogen-doped titania

“…The results of Diwald et al [30] rather indicate negative contribution of Ti-N bonding to photocatalytic activity. According to the reports [31,32], N 1s state at 400 eV in our doped samples of TiO 2 samples by the solvothermal method is in an oxidized state similar to -(NO) and interstitially dopant -(NH) from HMT, which can be attributed to the doping status of N 1s(II) at 398.8-401.2 eV classified by Chen et al [33]. The -(NO) and -(NH) dopants may have positive effects on the visible light photocatalytic activity.…”

Photocatalytic removal of NO and HCHO over nanocrystalline Zn2SnO4 microcubes for indoor air purification

“…Many approaches have been proposed to develop active and stable photocatalysts, including doping TiO 2 with metal ions or metal atoms, incorporating nitrogen and carbon into TiO 2 , and employing other non-TiO 2 metal oxides as photocatalysts [15][16][17][18][19][20][21][22][23][24]. Non-TiO 2 photocatalysts have attracted a great deal of attentions because of their high photocatalytic efficiency and potential application in environmental remediation [25][26][27][28][29].…”