Photocatalytic Activity of TiO₂Powders Synthesized by Supercritical Gas Antisolvent Method

Abstract

Synthesis of nanocrystalline, spherical, and anatase type TiO2 photocatalyst were performed by supercritical gas antisolvent process in the range of 50150 • C and 100150 bar. As-prepared samples were calcined at 500 • C and characterized by X-ray diraction, scanning electron microscopy, BrunauerEmmettTeller method, dierential thermal analysis/thermal gravimetry. In X-ray diraction analysis, the anatase crystalline phase of titanium dioxide has been detected. The mean crystalline size of powders is about 13 nm. The photoactivity test of the powders was evaluated by the photodegradation of aqueous RR 180 (reactive red 180) solution under UV light. While the photocatalytic performance of TiO2 powders (BrunauerEmmettTeller surface area of 69.2 m 2 /g) produced at 150 bar and 150 • C was found to be 98%, only 25% degradation was observed with powder produced at 150 bar and 100 • C. Results showed that the powder properties and photocatalytic activity can be tuned by controlling the supercritical conditions such as temperature and pressure.

Supercritical Carbon Dioxide-Based Processes in Photocatalytic Applications

“…Up to now, the Supercritical AntiSolvent (SAS) precipitation was widely used to produce nanoparticles of different materials, including metal-based compounds to produce catalysts [ 66 , 67 , 68 , 69 ] and photocatalysts [ 42 , 43 , 44 , 45 , 46 ] with very high activity and selectivity performance for various reactions.…”

“…Then, the as-prepared precursor particles have to be usually calcined at high temperatures to produce the final oxide photocatalyst. Isopropanol, dimethylsulfoxide (DMSO), ethanol and methanol are usually selected as the proper solvents for the precipitation of photocatalyst precursors [ 42 , 43 , 44 , 45 , 46 ].…”

“…The semi-conductive photocatalysts generally used are titanium dioxide or titania (TiO 2 ) [ 21 , 22 , 23 ], ZnO [ 24 , 25 ], WO 3 [ 26 , 27 ], Fe 2 O 3 [ 28 , 29 ], CeO 2 [ 30 , 31 ], MoO 3 [ 32 , 33 ], ZrO 2 [ 34 , 35 ], SnO 2 [ 36 , 37 ], CdS [ 38 , 39 ], and ZnS [ 40 , 41 ]. Up to now, semiconductor-based photocatalysts in various forms have been proposed, mainly as nanopowders [ 42 , 43 , 44 , 45 , 46 , 47 , 48 ] or aerogels [ 49 , 50 , 51 , 52 , 53 , 54 ], due to the high specific surface area of these materials, resulting in a very high contact between the semiconductor and the fluid to be treated and, consequently, the photocatalytic performance could be enhanced.…”

Coating of Ordered Large-Pore Mesoporous Silica with TiO2 Nanoparticles and Evaluation of Its Photocatalytic Activity

“…Over the last few years, TiO 2 as a photocatalyst has attracted researchers attention because of its competitive price, superior chemical stability, and nontoxicity [1][2][3][4]. However, limited photoactivity of titanium oxide can be considered as an obstacle to the industrial usage.…”

Facile Synthesis and Characterization of Zinc Tetranitro Phthalocyanine-MWCNTs Nanocomposites with Efficient Visible-Light-Driven Photocatalytic Activity

“…A large amount of photocatalytic materials have been investigated, including TiO 2 [5][6][7], ZnO [8,9], CdS [10,11], g-C 3 N 4 [12,13], etc. Among the reported photocatalytic materials, multi-walled carbon nanotubes (MWCNTs) as a novel metal free photocatalyst support have good photocatalytic performance under visible-light irradiation [14,15], and it also demonstrates the property of low cost, non-toxicity, and thermal stability [16].…”