Synergistic effect between anatase and rutile TiO2 nanoparticles in dye-sensitized solar cells

Abstract

A synergistic effect between anatase and rutile TiO2 is known, in which the addition of rutile can remarkably enhance the photocatalytic activity of anatase in the degradation of organic contaminants. In this study, mixed-phase TiO2 nanocomposites consisting of anatase and rutile nanoparticles (NPs) were prepared for use as photoanodes in dye-sensitized solar cells (DSSCs) and were characterized by using UV-vis spectroscopy, powder X-ray diffraction and scanning electron microscopy. The addition of 10-15% rutile significantly improved light harvesting and the overall solar conversion efficiency of anatase NPs in DSSCs. The underlying mechanism for the synergistic effect in DSSCs is now explored by using time-resolved terahertz spectroscopy. It is clearly demonstrated that photo-excited electrons injected into the rutile NPs can migrate to the conduction band of anatase NPs, enhancing the photocurrent and efficiency. Interfacial electron transfer from rutile to anatase, similar to that in heterogeneous photocatalysis, is proposed to account for the synergistic effect in DSSCs. Our results further suggest that the synergistic effect can be used to explain the beneficial effect of TiCl4 treatment on DSSC efficiency.

Enhancement of the electrochemical capacitance of TiO2 nanotube arrays through controlled phase transformation of anatase to rutile

“…Therefore, to apply TiO 2 in practice, the resultant material has to be annealed at relatively high temperatures. 18 In contrast with photocatalytic applications, in which it has been reported that a mixture of anatase and rutile phases is more efficient, 15,19 in energy storage applications such as batteries and supercapacitors, it has been stated that electrochemical properties of titania particles mostly depend on the size of the particles rather than the phases. To the best of authors' knowledge, there are no reports in the literature regarding the capacitance of such a mixture, and no significant differences are reported between rutile and anatase.…”

“…The search for alternative suitable materials has led to a renewed interest in titanium dioxide (TiO 2 ) based supercapacitors. TiO 2 , as a highly functional material with many interesting applications in diverse areas, including energy storage, 6,7 medicine, [8][9][10] photovoltaic, [11][12][13] sensors, 14 solar cells, 15 etc., has been considered as a hotspot for many applications. Recently, our group has developed new engineered energy devices based on oxygen depleted, highlyordered, self-organized titania nanotubes synthesized via anodic oxidation of titanium foil to overcome the high electrical resistivity of bare titania to meet the requirements for higher specific capacitance applications.…”

Effect of Au nano-particles on TiO2 nanorod electrode in dye-sensitized solar cells

“…The difference between the conduction band levels of anatase and rutile forms, however due to the low difference between the conduction band levels of anatase and rutile, the higher diffusion coefficient of anatase play more important role for the efficient electron transport in anatase [28] and therefore, favors the use of pure anatase for DSSC applications [24]. There are reports, however, that synergistic use of rutile and anatase polymorphs of TiO 2 nanoparticles could increase DSSC efficiency [24,25,27]. Such an effect is also observed in photocatalytic activity of anatase TiO 2 nano crystals, which significantly increases upon mixing with a portion of lesser active rutile nano crystals [29,30].…”

“…The crystal structure of TiO 2 also plays a factor in efficiency of DSSCs [24][25][26][27]. The difference between the conduction band levels of anatase and rutile forms, however due to the low difference between the conduction band levels of anatase and rutile, the higher diffusion coefficient of anatase play more important role for the efficient electron transport in anatase [28] and therefore, favors the use of pure anatase for DSSC applications [24]. There are reports, however, that synergistic use of rutile and anatase polymorphs of TiO 2 nanoparticles could increase DSSC efficiency [24,25,27].…”

Nanostructured Ceramic Photocatalytic Membrane Modified with a Polymer Template for Textile Wastewater Treatment

“…21-1272). The anatase phase is widely known to be more effective for photocatalytic reactions than the rutile and brookite phases [9,19]. From the XRD results, it was concluded that the organic species were completely removed and that a highly crystalline anatase TiO2 structure was obtained after calcination at 450 °C.…”