Heterophase Polymorph of TiO2 (Anatase, Rutile, Brookite, TiO2 (B)) for Efficient Photocatalyst: Fabrication and Activity

Abstract

TiO2 exists naturally in three crystalline forms: anatase, rutile, brookite, and TiO2 (B). These polymorphs exhibit different properties and consequently different photocatalytic performances. This paper aims to clarify the differences between titanium dioxide polymorphs, and the differences in homophase, biphase, and triphase properties in various photocatalytic applications. However, homophase TiO2 has various disadvantages such as high recombination rates and low adsorption capacity. Meanwhile, TiO2 heterophase can effectively stimulate electron transfer from one phase to another causing superior photocatalytic performance. Various studies have reported the biphase of polymorph TiO2 such as anatase/rutile, anatase/brookite, rutile/brookite, and anatase/TiO2 (B). In addition, this paper also presents the triphase of the TiO2 polymorph. This review is mainly focused on information regarding the heterophase of the TiO2 polymorph, fabrication of heterophase synthesis, and its application as a photocatalyst.

Mechanistic Understanding in Manipulating Energetics of TiO2 for Photocatalysis

“…There are other less prevalent polymorphs of TiO 2 that can have some photocatalytic applications, from photovoltaic to photocatalysis and, more recently, for solar cell devices and resistive switching. TiO 2 –B is a monoclinic phase of TiO 2 , exhibiting more open-structure than anatase, rutile, and brookite and has a unique one-dimensional (1D) open framework structure aligned along the b -axis, which sometimes presents a good pathway for gas reduction or ion diffusion . Solar cell technologies are the rising technologies, where dye-sensitized solar cells are a well-researched area that requires sensitization of TiO 2 –B.…”

“…TiO 2 −B is a monoclinic phase of TiO 2 , exhibiting more open-structure than anatase, rutile, and brookite and has a unique one-dimensional (1D) open framework structure aligned along the b-axis, which sometimes presents a good pathway for gas reduction or ion diffusion. 37 Solar cell technologies are the rising technologies, where dyesensitized solar cells are a well-researched area that requires sensitization of TiO 2 −B. Organic dyes adsorbed on TiO 2 −B do not change the band gap of TiO 2 but increase the capability of TiO 2 to absorb photons in the visible wavelength range by injecting electrons into the CB of TiO 2 .…”

In situ preparation of MOF-derived Fe2O3 nanorods for visible-light-driven oxygen evolution

“…It has been extensively investigated in various fields, including molecular sensing, battery technology, catalysis, gas adsorption and separation, biomedicine, drug delivery, template materials, and pesticide testing. [16][17][18][19] Researchers have developed multiplexed composites derived from MIL-101(Fe) to address the relatively inefficient separation of photogenerated charge carriers. These composites aim to reduce the recombination of electron-hole pairs generated during photocatalysis, enhancing overall photocatalytic performance.…”

Photocatalytic and antimicrobial efficacy of PVDF/TiO2 membranes fabricated by solution blow spinning

“…31,32 The photocatalytic performance of anatase is considered to be superior to other phases; however, much experimental evidence supports the existence of a synergistic effect of enhancing photocatalytic activity in crystalline TiO 2 containing anatase/rutile. 33 The mixed phase of TiO 2 reduces the recombination of photogenerated electrons and holes, thereby enhancing photocatalytic activity. For example, Degussa (Evonik) P25, 34,35 used as a standard TiO 2 photocatalyst, is a mixed phase.…”

“…It exists mainly in three different crystal forms: rutile (tetragonal), anatase (tetragonal), and brookite (orthorhombic) 31,32 . The photocatalytic performance of anatase is considered to be superior to other phases; however, much experimental evidence supports the existence of a synergistic effect of enhancing photocatalytic activity in crystalline TiO 2 containing anatase/rutile 33 . The mixed phase of TiO 2 reduces the recombination of photogenerated electrons and holes, thereby enhancing photocatalytic activity.…”