Enhanced Photocatalytic Hydrogen Production with Synergistic Two-Phase Anatase/Brookite TiO₂ Nanostructures

Abstract

Highly crystalline pure brookite and two-phase anatase/brookite TiO 2 nanostructures were synthesized via a simple hydrothermal method with titanium sulfide as the precursors in sodium hydroxide solutions. The control of the phase composition has been demonstrated via solution concentration and reaction time, and the phase transformation mechanism has been elucidated. Photocatalytic activities of the assynthesized two-phase anatase/brookite TiO 2 , pure anatase nanoparticles, and pure brookite nanoplates were appraised via photocatalytic hydrogen evolution in aqueous methanol solution. Results have shown that the photocatalytic activity is higher for the two-phase anatase/brookite TiO 2 and brookite nanoplates as compared to pure anatase nanoparticles despite the lower surface areas of the two-phase anatase/brookite TiO 2 and brookite nanoplates. From the Mott−Schottky analysis, brookite phase is shown to have a more cathodic conduction band edge potential than anatase phase, which leads to more energetically favorable hydrogen reduction. Moreover, femtosecond transient absorption spectroscopy measurements suggests that the photoexcited electrons transfer from brookite to anatase phaseleading to further enhancement of the photocatalytic activity. In comparison with the highly active two-phase commercial benchmark P25, our synthesized two-phase anatase/brookite TiO 2 is 220% more active when measured by the H 2 yield per unit area of the photocatalyst surface.

Development of bifunctional microencapsulated phase change materials with crystalline titanium dioxide shell for latent-heat storage and photocatalytic effectiveness

“…29-1360. This diffraction result is also in good agreement with the reported data [30,35]. On the other hand, there is no diffraction peak appearing in the XRD pattern of the microcapsule sample synthesized without the incorporation of fluorinions.…”

Effect of TiO2 polymorph and alcohol sacrificial agent on the activity of Au/TiO2 photocatalysts for H2 production in alcohol–water mixtures

“…Similar positive synergies have also been reported in brookite-rutile and anatase-brookite systems (possible since the conduction bands of anatase, brookite and rutile are offset at À0.5, À0.6 and À0.7 V versus SHE, respectively). The effect of the TiO 2 support composition on the activity of M/TiO 2 photocatalysts for H 2 production in alcohol-water systems has been the subject of a number of investigations [27,[33][34][35], but very few studies actually encompass all three TiO 2 polymorphs and biphasic supports such as P25. Gauging the relative merits of P25, anatase, brookite and rutile as supports from existing literature is not straightforward, as additional factors including TiO 2 crystallite size, crystallite shape, surface area and photocatalytic test conditions also strongly impact H 2 production rates in M/TiO 2 systems.…”

Preparation and characterization of TiO 2 -based nanosheets for photocatalytic degradation of acetylsalicylic acid: Influence of calcination temperature

“…Notably, over the past several decades, studies of using TiO 2 as a photocatalyst in wastewater treatment has been widely investigated and TiO 2 is still the most popular photocatalytic material owing to its intrinsic attributes, including the high photoreactivity, non-toxicity, low cost, superior oxidizability and long-lived(around 250ns) charge carriers [7][8][9][10][11]. Generally, TiO 2 exists in three most commonly polymorphs: brookite, anatase and rutile [12]. Among the three polymorphs only brookite has not been employed as the photocatalyst because of its metastable structure [13].…”