Electronic structure and the optical and photocatalytic properties of anatase doped with vanadium and carbon

Optical and Photocatalytic Properties of Carbon-Activated Anatase with Spherical Shape of Aggregates

“…The authors of work [47] took into account the possibility of spin polarization and arrived at the conclusion that at distances between carbon atoms of 1.5 Å the compound should be paramagnetic, whereas at 3.8 Å or longer distances it should be ferro-or antiferroordered with magnetic moment of carbon atoms equal to 2l B . The latter inference does not correspond to the calculation results [48,49], according to which carbon atoms, as distinct from boron and nitrogen atoms, are not in the spin-polarized state. So in this work we have carried out new first-principles calculations of the electronic band structure and optical absorption spectra, and analyzed the probabilities of formation of the carbon for oxygen substitutional defects and interstitial defects, which allowed us to determine the dominant type of defects responsible for absorption and photocatalytic activity in the visible region.…”

Synthesis, spectral, optical and photocatalytic properties of vanadium- and carbon-doped titanium dioxide with three-dimensional architecture of aggregates

“…The samples were synthesized by the precursor method with the use of glycolate of the composition Ti 1-x V x (OCH 2 CH 2 O) 2 (0≤x≤0.05) as a precursor taking into account that the crystals of this compound are able to undergo a pseudomorphous transformation into aggregates Ti 1-x V x O 2 , Ti 1-x V x O 2-y C y and Ti 1-x V x O 2-y C y :nC during heating under pre-assigned conditions [25][26][42][43][44][45]. To produce a precursor with spherical shape of crystal aggregates, we have developed a technique allowing for the following reactions: 2 have a pale yellow color, which intensifies with the growth of the concentration of vanadium.…”

“…For example, using titanium glycolate Ti(OCH 2 CH 2 O) 2 and solid solutions based thereon of the general composition Ti 1-x M x (OCH 2 CH 2 O) 2 as precursors, it is possible to synthesize both pure and transition-element and carbon-doped titanium dioxide in the form of nanodispersed solid solutions TiO 2-y C y , Ti 1-x M x O 2 , Ti 1-x M x O 2-y C y and nanocomposites TiO 2-y C y :nC, Ti 1-x M x O 2-y C y :nC with pre-assigned concentration of impurity elements and controlled dimensional and morphological characteristics of particles [25][26][40][41][42][43][44][45][46]. In most cases, the morphology and dimensions of precursor crystals depend on the method of their production.…”

“…Thermolysis of Ti 1-x V x (OCH 2 CH 2 O) 2 in inert atmosphere at 500°C gives rise to Ti 1-x V x O 2-y C y :nC composites, whose aggregates have extended shape and are built of autonomous layers of titaniumcontaining phase with anatase structure and free carbon [25][26]. By varying the ratio of the reaction mixture components including titanium tetrabutoxide Ti(C 4 H 9 O) 4 and ethylene glycol, as well as the synthesis conditions, we obtained samples of titanium glycolate Ti(OCH 2 CH 2 O) 2 with threedimensional near-spherical architecture of crystal aggregates [46].…”

“…The introduction of impurities forming additional energy levels in the band gap of the semiconductor makes it possible to change its band gap and to affect the concentration and mobility of free charge carriers (electrons and holes) participating in redox reactions during photocatalysis. The greatest efficiency as a dopant was exhibited by vanadium -even small additions of it into anatase structure lead to visible light photocatalytic effect [22][23][24][25][26][27][28][29][30]. Besides doping, the photocatalytic properties of titanium dioxide can be tuned by changing the size and morphology of its particles, as well as by modification of their bulk and surface characteristics [31][32][33][34][35][36][37][38][39].…”