Recent advances in the synthesis of hierarchically mesoporous TiO2 materials for energy and environmental applications

Abstract

Because of their low cost, natural abundance, environmental benignity, plentiful polymorphs, good chemical stability and excellent optical properties, TiO2 materials are of great importance in the areas of physics, chemistry and material science. Much effort has been devoted to the synthesis of TiO2 nanomaterials for various applications. Among them, mesoporous TiO2 materials, especially with hierarchically porous structures, show great potential owing to their extraordinarily high surface areas, large pore volumes, tunable pore structures and morphologies, and nanoscale effects. This review aims to provide an overview of the synthesis and applications of hierarchically mesoporous TiO2 materials. In the first section, the general synthetic strategies for hierarchically mesoporous TiO2 materials are reviewed. After that, we summarize the architectures of hierarchically mesoporous TiO2 materials, including nanofibers, nanosheets, microparticles, films, spheres, core-shell and multi-level structures. At the same time, the corresponding mechanisms and the key factors for the controllable synthesis are highlighted. Following this, the applications of hierarchically mesoporous TiO2 materials in terms of energy storage and environmental protection, including photocatalytic degradation of pollutants, photocatalytic fuel generation, photoelectrochemical water splitting, catalyst support, lithium-ion batteries and sodium-ion batteries, are discussed. Finally, we outline the challenges and future directions of research and development in this area.

Weaving 3D highly conductive hierarchically interconnected nanoporous web by threading MOF crystals onto multi walled carbon nanotubes for high performance Li–Se battery

“…After 100 cycles, the R ct of Se@3D MIL-68 (Al) @MWCNTs electrode further decreases to 28.7 X, only half of Se@MIL-68 (Al) (56.8 X). This confirms the highly enhanced electrical conductivity and Li + diffusion in 3D highly conductive MIL-68 (Al)@MWCNTs web [41][42][43][44] .…”

Connecting theory and simulation with experiment for the study of diffusion in nanoporous solids

“…Due to its versatility, metals and metal oxides supported on TiO 2 have been intensively studied in heterogeneous, thermal and photocatalysis, e.g., in a variety of mild oxidation reactions, including ethane to acetic acid, ethanol to acetaldehyde and oxidative dehydrogenation of propane to propylene. The properties and applications of TiO 2 in catalysis are reviewed by Bagheri et al [397], Niu et al [398], and Zhang et al [399], among others. TiO 2 exists in three crystalline forms: anatase, rutile, and brookite.…”

“…TiO 2 nanofibers and nanosheets possess one-dimensional and two-dimensional porous structures, respectively. Many other structures have been created as well [399]. Various TiO 2 supported catalysts, e.g., Au/TiO 2 , Pd/TiO 2 , Co/TiO 2 , and Pt/TiO 2 , have been developed for industrial applications, including the hydrodesulfurization of hydrocarbon oils, the epoxidation of propene, and the selective catalytic reduction of NO with NH 3 [397].…”

Synthesis and Crystal-Phase Engineering of Mesoporous Palladium–Boron Alloy Nanoparticles

“…Periodically ordered mesoporous materials, with pore sizes of 2–50 nm, have attracted great research interest in the past three decades because of their high porosities, large surface areas, and tunable pore sizes. 16 − 20 In comparison to traditional mesoporous carbons and oxides, mesoporous NMs (for example, mesoPd, mesoPt, and mesoAu) present many novel physicochemical properties that are inherent to metal frameworks ( e.g ., good electrical and thermal conductivities, high catalytic activities) along with structural features (mesoporosities). This thus endows their better performances toward various catalytic and optical applications.…”