6 research outputs found
Photocatalytic Properties of Sn-doped TiO2
The synthesis of Sn-doped titania nanoparticles (Sn content of 0, 3, 6, and 12 at. %) was carried out using solgel chemical route based on the common acid hydrolysis of titanium and tin tetrachlorides. Phase composition,
morphology, particle size, pore size distribution and photocatalytic performance of obtained materials were systematically studied by various analytical techniques (XRD, HR-TEM, low-temperature nitrogen adsorption porosimetry, UV-Vis spectroscopy). An increase in the Sn dopant concentration causes a gradual decrease in the
relative content of the anatase phase from 100 mol. % for undoped titania to about 3 mol. % for material with
maximal doping concentration. Materials with a Sn atomic content of 3 and 6 at. % have the maximum values of
the specific surface area (about 280-290 m2/g) that corresponds to the smallest (approximately 2.5 nm) anatase
crystallite. The photocatalytic activity of the synthesized Sn-doped TiO2 nanoparticles was analyzed by the
method of methylene blue dye photodegradation in an aqueous solution under UV irradiation. The highest reaction rate constant and maximal methylene blue dye adsorption capacity were obtained for 3 at. % Sn-doped titania with the mixed anatase/rutile composition. The indirect optical transitions are characteristic for all synthesized materials. A decrease in the bandgap energy values with increasing Sn content from 3.21 eV for pure anatase to 2.82 eV for titania doped with 12 at. % of the Sn was observed. The growth in photocatalytic activity for
the mixed-phase sample can be considered as a result of the increasing number of surface active centers due to
the anatase-rutile phase transition
RUTILE NANORODS: SYNTHESIS, STRUCTURE AND ELECTROCHEMICAL PROPERTIES
Nanodispersed rutile with rod-like particles was synthesized by hydrolysis of TiCl4 in hydrochloric acid - ethanol alcohol aqueous solution at 40Β°C. It was found that the specific surface area, crystallite size, degree of agglomeration are determined by molar ratios of ethanol. The obtained material was used as the base of cathode composition for lithium power sources. The maximum values of specific capacity (250 mAh/g) at discharge in galvanostatic conditions are fixed in the case of using material with the maximum agglomeration degree and minimal particle size. Phasic character of Li+ ions intercalation is set and the diffusion coefficient at different stages of the process is calculated.</p
Π ΠΎΠ·ΠΌΡΡΠ½ΠΈΠΉ Π΅ΡΠ΅ΠΊΡ Ρ Π½Π°Π½ΠΎΡΠ°ΡΡΠΈΠ½ΠΊΠ°Ρ ΡΡΠΈΠΌΠ΅ΡΠΈΠ»ΡΠΈΠ»ΡΠ»ΡΠΎΠ²Π°Π½ΠΎΠ³ΠΎ ΠΊΡΠ΅ΠΌΠ½Π΅Π·Π΅ΠΌΡ
The synthesis of organosilicas with a predetermined ratio of trimethylsilyl groups and silanols using
trimethyloxysilane and acetic acid as a modifier and catalyst respectively was carried out in this work. It
has been established that grafted trimethylsilyl groups influence the structural state of silica. The reducing
of the surface tension and, consequently, the Laplace pressure in the SiO2 globules leads to an increase
in the valence angle in the siloxane bridges and the length of Si β O-bond. This dimensional effect in the
IR-spectra of modified silica is displayed by displacement of absorption bands in the short-wave region associated
with asymmetric (a) and asymmetric-deformation (Π° + Ξ΄O Si O) vibrations of siloxane bridges.Π£ ΡΠΎΠ±ΠΎΡΡ ΠΏΡΠΎΠ²Π΅Π΄Π΅Π½ΠΎ ΡΠΈΠ½ΡΠ΅Π· ΠΎΡΠ³Π°Π½ΠΎΠΊΡΠ΅ΠΌΠ½Π΅Π·Π΅ΠΌΡΠ² Π· Π½Π°ΠΏΠ΅ΡΠ΅Π΄ Π·Π°Π΄Π°Π½ΠΈΠΌ ΡΠΏΡΠ²Π²ΡΠ΄Π½ΠΎΡΠ΅Π½Π½ΡΠΌ ΡΡΠΈΠΌΠ΅ΡΠΈΠ»ΡΠΈΠ»Ρ-
Π»ΡΠ½ΠΈΡ
Π³ΡΡΠΏ ΡΠ° ΡΠΈΠ»Π°Π½ΠΎΠ»ΡΠ², Π²ΠΈΠΊΠΎΡΠΈΡΡΠΎΠ²ΡΡΡΠΈ ΡΡΠΈΠΌΠ΅ΡΠΈΠ»Π΅ΡΠΎΠΊΡΡΡΠΈΠ»Π°Π½ ΡΠ° ΠΎΡΡΠΎΠ²Ρ ΠΊΠΈΡΠ»ΠΎΡΡ Π²ΡΠ΄ΠΏΠΎΠ²ΡΠ΄Π½ΠΎ ΡΠΊ ΠΌΠΎ-
Π΄ΠΈΡΡΠΊΠ°ΡΠΎΡ Ρ ΠΊΠ°ΡΠ°Π»ΡΠ·Π°ΡΠΎΡ. ΠΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½ΠΎ, ΡΠΎ ΠΏΡΠΈΡΠ΅ΠΏΠ»Π΅Π½Ρ ΡΡΠΈΠΌΠ΅ΡΠΈΠ»ΡΠΈΠ»ΡΠ»ΡΠ½Ρ Π³ΡΡΠΏΠΈ Π²ΠΏΠ»ΠΈΠ²Π°ΡΡΡ Π½Π° ΡΡΡΡΠΊ-
ΡΡΡΠ½ΠΈΠΉ ΡΡΠ°Π½ ΠΊΡΠ΅ΠΌΠ½Π΅Π·Π΅ΠΌΡ. ΠΠΌΠ΅Π½ΡΠ΅Π½Π½Ρ ΠΏΠΎΠ²Π΅ΡΡ
Π½Π΅Π²ΠΎΠ³ΠΎ Π½Π°ΡΡΠ³Ρ Ρ Π²ΡΠ΄ΠΏΠΎΠ²ΡΠ΄Π½ΠΎ ΠΠ°ΠΏΠ»Π°ΡΠΎΠ²ΠΎΠ³ΠΎ ΡΠΈΡΠΊΡ Π² Π³Π»ΠΎΠ±ΡΠ»Π°Ρ
SiO2 ΠΏΡΠΈΠ²ΠΎΠ΄ΠΈΡΡ Π΄ΠΎ Π·Π±ΡΠ»ΡΡΠ΅Π½Π½Ρ Π²Π°Π»Π΅Π½ΡΠ½ΠΎΠ³ΠΎ ΠΊΡΡΠ° Π² ΡΠΈΠ»ΠΎΠΊΡΠ°Π½ΠΎΠ²ΠΈΡ
ΠΌΡΡΡΠΊΠ°Ρ
ΡΠ° Π΄ΠΎΠ²ΠΆΠΈΠ½ΠΈ Si β O-Π·Π²βΡΠ·ΠΊΡ. Π
ΠΠ§-ΡΠΏΠ΅ΠΊΡΡΠ°Ρ
ΠΌΠΎΠ΄ΠΈΡΡΠΊΠΎΠ²Π°Π½ΠΈΡ
ΠΊΡΠ΅ΠΌΠ½Π΅Π·Π΅ΠΌΡΠ² Π΄Π°Π½ΠΈΠΉ ΡΠΎΠ·ΠΌΡΡΠ½ΠΈΠΉ Π΅ΡΠ΅ΠΊΡ ΠΏΡΠΎΡΠ²Π»ΡΡΡΡΡΡ Π·ΠΌΡΡΠ΅Π½Π½ΡΠΌ Ρ ΠΊΠΎΡΠΎΡΠΊΠΎ-
Ρ
Π²ΠΈΠ»ΡΠΎΠ²Ρ ΠΎΠ±Π»Π°ΡΡΡ ΡΠΌΡΠ³ ΠΏΠΎΠ³Π»ΠΈΠ½Π°Π½Π½Ρ, ΠΏΠΎΠ²βΡΠ·Π°Π½ΠΈΡ
Π· Π°ΡΠΈΠΌΠ΅ΡΡΠΈΡΠ½ΠΈΠΌΠΈ (a) ΡΠ° Π°ΡΠΈΠΌΠ΅ΡΡΠΈΡΠ½ΠΈΠΌΠΈ Ρ Π΄Π΅ΡΠΎΡΠΌΠ°-
ΡΡΠΉΠ½ΠΈΠΌΠΈ (a + Ξ΄O Si O) ΠΊΠΎΠ»ΠΈΠ²Π°Π½Π½ΡΠΌΠΈ ΡΠΈΠ»ΠΎΠΊΡΠ°Π½ΠΎΠ²ΠΈΡ
ΠΌΡΡΡΠΊΡΠ².Π ΡΠ°Π±ΠΎΡΠ΅ ΠΏΡΠΎΠ²Π΅Π΄Π΅Π½ ΡΠΈΠ½ΡΠ΅Π· ΠΎΡΠ³Π°Π½ΠΎΠΊΡΠ΅ΠΌΠ½Π΅Π·Π΅ΠΌΠΎΠ² Ρ Π·Π°ΡΠ°Π½Π΅Π΅ Π·Π°Π΄Π°Π½Π½ΡΠΌ ΡΠΎΠΎΡΠ½ΠΎΡΠ΅Π½ΠΈΠ΅ΠΌ ΡΡΠΈΠΌΠ΅ΡΠΈΠ»ΡΠΈ-
Π»ΠΈΠ»ΡΠ½ΠΈΡ
Π³ΡΡΠΏΠΏ ΠΈ ΡΠΈΠ»Π°Π½ΠΎΠ»Π°, ΠΈΡΠΏΠΎΠ»ΡΠ·ΡΡ ΡΡΠΈΠΌΠ΅ΡΠΈΠ»Π΅ΡΠΎΠΊΡΠΈΡΠΈΠ»Π°Π½ ΠΈ ΡΠΊΡΡΡΠ½ΡΡ ΠΊΠΈΡΠ»ΠΎΡΡ ΡΠΎΠΎΡΠ²Π΅ΡΡΡΠ²Π΅Π½Π½ΠΎ ΠΊΠ°ΠΊ
ΠΌΠΎΠ΄ΠΈΡΠΈΠΊΠ°ΡΠΎΡ ΠΈ ΠΊΠ°ΡΠ°Π»ΠΈΠ·Π°ΡΠΎΡ. Π£ΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½ΠΎ, ΡΡΠΎ ΠΏΡΠΈΠ²ΠΈΡΡΠ΅ ΡΡΠΈΠΌΠ΅ΡΠΈΠ»ΡΠΈΠ»ΠΈΠ»ΡΠ½ΡΠ΅ Π³ΡΡΠΏΠΏΡ Π²Π»ΠΈΡΡΡ Π½Π°
ΡΡΡΡΠΊΡΡΡΠ½ΠΎΠ΅ ΡΠΎΡΡΠΎΡΠ½ΠΈΠ΅ ΠΊΡΠ΅ΠΌΠ½Π΅Π·Π΅ΠΌΠ°. Π£ΠΌΠ΅Π½ΡΡΠ΅Π½ΠΈΠ΅ ΠΏΠΎΠ²Π΅ΡΡ
Π½ΠΎΡΡΠ½ΠΎΠ³ΠΎ Π½Π°ΡΡΠΆΠ΅Π½ΠΈΡ ΠΈ ΡΠΎΠΎΡΠ²Π΅ΡΡΡΠ²Π΅Π½Π½ΠΎ ΠΠ°ΠΏΠ»Π°-
ΡΠΎΠ²ΠΎΠ³ΠΎ Π΄Π°Π²Π»Π΅Π½ΠΈΡ Π² Π³Π»ΠΎΠ±ΡΠ»Π°Ρ
SiO2 ΠΏΡΠΈΠ²ΠΎΠ΄ΠΈΡ ΠΊ ΡΠ²Π΅Π»ΠΈΡΠ΅Π½ΠΈΡ Π²Π°Π»Π΅Π½ΡΠ½ΠΎΠ³ΠΎ ΡΠ³Π»Π° Π² ΡΠΈΠ»ΠΎΠΊΡΠ°Π½ΠΎΠ²ΡΡ
ΠΌΠΎΡΡΠΈΠΊΠ°Ρ
ΠΈ
Π΄Π»ΠΈΠ½Ρ Si β O-ΡΠ²ΡΠ·ΠΈ. Π ΠΠ-ΡΠΏΠ΅ΠΊΡΡΠ°Ρ
ΠΌΠΎΠ΄ΠΈΡΠΈΡΠΈΡΠΎΠ²Π°Π½Π½ΡΡ
ΠΊΡΠ΅ΠΌΠ½Π΅Π·Π΅ΠΌΠΎΠ² Π΄Π°Π½Π½ΡΠΉ ΡΠ°Π·ΠΌΠ΅ΡΠ½ΡΠΉ ΡΡΡΠ΅ΠΊΡ ΠΏΡΠΎ-
ΡΠ²Π»ΡΠ΅ΡΡΡ ΡΠΌΠ΅ΡΠ΅Π½ΠΈΠ΅ΠΌ Π² ΠΊΠΎΡΠΎΡΠΊΠΎΠ²ΠΎΠ»Π½ΠΎΠ²ΡΡ ΠΎΠ±Π»Π°ΡΡΡ ΠΏΠΎΠ»ΠΎΡ ΠΏΠΎΠ³Π»ΠΎΡΠ΅Π½ΠΈΡ, ΡΠ²ΡΠ·Π°Π½Π½ΡΡ
Ρ Π°ΡΠΈΠΌΠΌΠ΅ΡΡΠΈΡΠ½ΡΠΌΠΈ (a)
ΠΈ Π°ΡΠΈΠΌΠΌΠ΅ΡΡΠΈΡΠ½ΡΠΌΠΈ-Π΄Π΅ΡΠΎΡΠΌΠ°ΡΠΈΠΎΠ½Π½ΡΠΌΠΈ (a + Ξ΄O Si O) ΠΊΠΎΠ»Π΅Π±Π°Π½ΠΈΡΠΌΠΈ ΡΠΈΠ»ΠΎΠΊΡΠ°Π½ΠΎΠ²ΡΡ
ΠΌΠΎΡΡΠΈΠΊΠΎΠ²