Highly Active TiO2 Microspheres Formation in the Presence of Ethylammonium Nitrate Ionic Liquid

Abstract

Spherical microparticles of TiO 2 were synthesized by the ionic liquid-assisted solvothermal method at different reaction times (3, 6, 12, and 24 h). The properties of the prepared photocatalysts were investigated by means of UV-VIS diffuse-reflectance spectroscopy (DRS), Brunauer-Emmett-Teller (BET) surface area measurements, scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), and X-ray photoelectron spectroscopy (XPS). The results indicated that the efficiency of the phenol degradation was related to the time of the solvothermal synthesis, as determined for the TiO 2 _EAN(1:1)_24h sample. The microparticles of TiO 2 _EAN(1:1)_3h that formed during only 3 h of the synthesis time revealed a really high photoactivity under visible irradiation (75%). This value increased to 80% and 82% after 12 h and 24 h, respectively. The photoactivity increase was accompanied by the increase of the specific surface area, thus the poresize as well as the ability to absorb UV-VIS irradiation. The high efficiency of the phenol degradation of the ionic liquid (IL)-TiO 2 photocatalysts was ascribed to the interaction between the surface of the TiO 2 and ionic liquid components (carbon and nitrogen). effectiveness of the photocatalysis [5,6]. The extension of the TiO 2 spectral response range to absorb the photons under visible (43%) or/and near infrared (49% of solar spectrum energy) irradiation is crucial for this purpose. The TiO 2 photocatalytic properties can be controlled and their optical response can be expanded to absorb photons under visible or/and near infrared light irradiation through the alteration of the TiO 2 bandgap via morphology engineering [7][8][9][10].It was found that, after excitation, the electrons and holes propagate to the nano-and micro-particles surface where they react with electron acceptors and donors, respectively [6,9,11,12]. Additionally, it has been noted that a slower recombination rate and a larger surface area accounted for more active adsorption/desorption reactions and the surface transfer of photoexcited electrons [9,12,13], whereas the potential adverse effects that originate in the highly defective sites, typically developing with the growth of a large surface area, may be rectified by a higher crystallization of the particles [9].Ionic liquids (ILs) have gained increasing attention in terms of their assistance in TiO 2 synthesis as solvents as well as spatial and, perhaps, band structuring agents. Their high viscosity, dielectric constant, and thus polarity and dispersal capacity are widely recognized as the properties responsible for the charge, steric, and viscous stabilization of small-sized slow-growing crystallites, as well as the hindrance of aggregation and agglomeration processes that are disadvantageous for photocatalytic [7,10,11,[14][15][16][17][18][19][20][21][22][23].The synthesized photocatalysts in the presence of ILs nano-and microparticles are characterized by a larger specific surface area, higher crystallization level, and less crystalline defects [17]. ...

Highly Efficient Visible‐Light‐Induced Photocatalytic Hydrogen Production via Water Splitting using FeCl3‐Based Ionic Liquids as Homogeneous Photocatalysts

“…This explication is in a strong agreement with several research studies, which reported that IL-modified metal oxides could exhibit better photocatalytic activity than the bare metal oxides since they have less energy bandgaps. [37,43,50,51] Additionally, the increase of [OMIM]Br content in the photocatalyst to represent half its molar composition is another reason behind its elevated hydrogen productivity. Specifically, this increment could further inhibit the recombination of charge carriers during the excitation state of the photocatalyst.…”

Facile Formation of Self-Organized TiO2 Nanotubes in Electrolyte Containing Ionic Liquid-Ethylammonium Nitrate and Their Remarkable Photocatalytic Properties

“…On the basis of our previous research on the preparation of TiO 2 microspheres via the ionic liquid assisted solvothermal method, [EAN]­[NO 3 ] was chosen as a structural agent promoting preparation of photocatalyst with an extremely high photocatalytic activity under visible irradiation . Therefore, in this study, we aimed to assess the effect of this IL on the structure, surface, and photocatalytic activity of TiO 2 NTs prepared in the electrochemical way.…”

Theoretical and Experimental Studies on the Visible Light Activity of TiO2 Modified with Halide-Based Ionic Liquids

“…In this regard, a controllable preparation of the functional TiO2 semiconductor employing ionic liquids is a new and effective approach [10,11]. Nevertheless, the mechanism of IL action and their role in the TiO2 photoactivity enhancement have not been fully explained yet.…”