Effect of gamma radiation on the photocatalytic properties of Cu doped titania nanoparticles

Abstract

The aim of this paper is to study the effect of gamma-rays on structural, physicochemical, optical and photocatalytic performance of TiO 2 nanoparticles doped with different concentrations of copper ranging from 0 to 6 at.%. The powders have been prepared by sol-gel technique and annealed at 400 °C. They were irradiated by gamma-rays with doses varying from 14 to 60 KGy. These investigations confirm the formation of anatase TiO 2 nanoparticles and Cu 2+ ion substitution for Ti 4+ sites within the TiO 2 structure. This study also shows that, once the TiO 2 structure is saturated with copper, a metallic copper segregation is formed at the crystallite surfaces. After gamma irradiation, samples present a crystalline core and a disordered shell structure as a result of the formation of oxygen vacancies. Such oxygen vacancies at the TiO 2 nanocrystal surface lead to a remarkable enhancement of the photocatalytic activity of Cu-doped TiO 2 catalysts.

Effect of the Microstructure of the Semiconductor Support on the Photocatalytic Performance of the Pt-PtOx/TiO2 Catalyst System

“…These so-called weak absorption tails in semiconductors indicate the presence of localized electronic states in the bandgap region, which are traditionally connected to structural disorder [ 63 ]. Similar long tails have appeared in the absorbance spectra of TiO 2 nanomaterials prepared by sol–gel-like techniques [ 64 , 65 ] including our previous work [ 50 ], or even in the case of well-crystallized anatase particles after surface amorphization by gamma irradiation [ 66 ]. The disorder in these systems was attributed to the low preparation temperatures, and, to a smaller extent to the incorporation of oxygen vacancies.…”

“…It appears that the magnitude of the ESR signal correlates to some extent with the magnitude of the weak absorption tail of the optical absorption spectra. Indeed, if one accepts that the narrow ESR signal around g ≈ 2.00 is connected to oxygen vacancies, it is plausible to assume that electronic transitions associated with these defects should give a relevant contribution to the weak absorption region, even if no distinct absorption band due to oxygen vacancies (around 500 nm/2.5 eV [ 66 ]) can be identified in the spectra of Figure 3 or Figure S4 . It may be worth noting that the presence of reducing agents such as active carbon [ 32 ] or ammonia [ 69 ] was found to be responsible for the formation of oxygen vacancies during calcination of titania obtained from hydrolysis of titanium-isopropoxide.…”

Effect of γ-irradiation on ruthenium-morin nanocomposite for trace detection of Ce(IV), Ce(III) and Dy(III)

“…5C and 6C). The smaller particle size in Set B samples is due to the effect of high energy gamma irradiations that hinders in the particle aggregation in the medium [46,47].…”

Thermal behavior of Cu-doped TiO2 gels synthesized by the sol-gel method

“…Among them, the sol-gel method is often used to synthesize doped TiO 2 because it has advantages such as high purity, relatively low processing temperature and offers the possibility of controlling stoichiometry. 9,[21][22][23][24][25][26][27] In the case of Cu doped TiO 2 system previous papers were published. In these papers low amount of Cu and mainly inorganic Cu reagents were used, as the following: copper (II) trioxonitrate (V) (0.033 g), 19 copper sulphate pentahydrate (0.5 mol %), 20 copper (II) chloride anhydrous (1 mol.%) 22 or copper chloride dihydrate (0 to 6 at.…”

“…In these papers low amount of Cu and mainly inorganic Cu reagents were used, as the following: copper (II) trioxonitrate (V) (0.033 g), 19 copper sulphate pentahydrate (0.5 mol %), 20 copper (II) chloride anhydrous (1 mol.%) 22 or copper chloride dihydrate (0 to 6 at. %) 23 and cooper (II) nitrate/Me(NO 3 )x/TIP = 0.015 molar ratio. 24 In the present paper, the sol-gel preparation of Cu doped TiO 2 nanometric powders is discussed, as well as the influence of the amount of dopant on the thermal behavior of the synthesized samples and on the structure and properties of the resulted nanopowders.…”