Mesoporous Foam TiO₂ Nanomaterials for Effective Hydrogen Production

Abstract

Hydrolysis of TiCl4 in a diether-functionalized imidazolium ionic liquid (IL), namely 1-methyl-3-[2-(2-methoxy(ethoxy)ethyl]imidazolium methane sulfonate (M(MEE)I⋅CH3 SO3 ), results in a heterostructured organic/inorganic and sponge-like porous TiO2 material. The thermal treatment (300 °C) followed by calcination (500 °C) affords highly porous TiO2 . The characterization of the obtained samples (with and without IL, before and after calcination) by XRD, SEM, and TEM reveals TiO2 anatase crystalline phases and irregular-shaped particles with different porous structures. These hierarchical-structured mesoporous TiO2 nanomaterials were employed as efficient photocatalysts in the water-splitting process, yielding up to 1304 μmol g(-1) on hydrogen production.

3D Printed Scaffolds for Monolithic Aerogel Photocatalysts with Complex Geometries

“…[19] A solution to this problem is the fabrication of templatefree, macroscopic, 3D structures entirely made of the photocatalytic material. Examples along these lines include 3D porous g-C 3 N 4 , [30] mesoporous TiO 2 foams, [31] graphene oxide (GO) sponges, [32] porous g-C 3 N 4 monoliths, [33] MoS 2 /rGO aerogels, [34] CN aerogels, [35] or Au-Pt-TiO 2 aerogels. [36] Unfortunately, the Monolithic aerogels composed of crystalline nanoparticles enable photocatalysis in three dimensions, but they suffer from low mechanical stability and it is difficult to produce them with complex geometries.…”

Engineered Inks for Environment-Friendly Additive Manufacturing of Hierarchical Microstructures

“…The latter being reported for the first time. This approach represents clear progress in the fabrication of TiO2 foams, traditionally fabricated using laborious multi-step methods [157,162,[169][170][171]. Special emphasis is placed in investigating the relationships between the foams' composition, processing, microstructure, surface area properties, and photocatalytic performance.…”

“…Ceramic based foams are highly desirable material systems because of their ability to mimic hierarchical organization widely existing in biological organisms [145]. Such organization is beneficial in numerous applications from catalysis [36,[157][158][159] to energy harvesting [39,[160][161][162] and storage [163], to biomedical [164][165][166].…”

“…Some of the challenges associated to the conventional synthesis of ceramic foams include the repetitive impregnation (or incorporation) and calcination removal of organic templates [11,157]; or the time sensitive handling of rapid-hydrolyzing of liquid-liquid [169,170] and gas-liquid [171] emulsions systems. More recent methods, include the decomposition reaction of TiCl4 within aqueous-organic solvent mixtures, in which the pores are generated by HCl toxic fumes as a by-product of the hydrolysis of the Tiprecursor [162]. Developments on the colloidal processing of hierarchical mesoporous cellular ceramics are of great interest because of the versatility that colloidal science brings to manufacturing.…”

“…Other works [289] suggest that anatase phase is also possible if the alkoxide to water volume ratio is 1:2. Recently, the synthesis of TiO2 foams from TiCl4 in the presence of an ionic liquid was demonstrated where crystalline TiO2 is obtained from solution reactions without the need of calcination processes [290].…”