Controllable synthesis and self-template phase transition of hydrous TiO2 colloidal spheres for photo/electrochemical applications

Dongwei Ma; Jenny Schneider; Wan In Lee; Jia Hong Pan

doi:10.1016/j.cis.2021.102493

Controllable synthesis and self-template phase transition of hydrous TiO₂ colloidal spheres for photo/electrochemical applications

Adv Colloid Interface Sci. 2021 Sep:295:102493. doi: 10.1016/j.cis.2021.102493. Epub 2021 Jul 21.

Authors

Dongwei Ma¹, Jenny Schneider², Wan In Lee³, Jia Hong Pan⁴

Affiliations

¹ MOE Key Laboratory of Resources and Environmental Systems Optimization, College of Environmental Science and Engineering, North China Electric Power University, Beijing 102206, China.
² Department of Chemistry, Ludwig-Maximilians-Universität (LMU) München, Butenandtstraße 1 11, D-81377 München, Germany.
³ Department of Chemistry and Chemical Engineering, Inha University, Incheon 22212, Republic of Korea. Electronic address: wanin@inha.ac.kr.
⁴ MOE Key Laboratory of Resources and Environmental Systems Optimization, College of Environmental Science and Engineering, North China Electric Power University, Beijing 102206, China. Electronic address: pan@ncepu.edu.cn.

PMID: 34332279
DOI: 10.1016/j.cis.2021.102493

Abstract

Hydrous TiO₂ colloidal spheres (HTCS) derived from the direct precipitation of titanium alkoxides have attracted continuous interests since 1982. Entering the 21st century, rapid progress in the development of structure-directing agents (SDAs) have enabled reproducible and size-controllable synthesis of highly uniform HTCS with diameters in the nano- to micro-meter range. The availability of various HTCS provides versatile self-templating platforms for the targeted synthesis of nanoporous TiO₂ and titanate spheres with tunable composition, crystallographic phases, and internal structures for a variety of advanced photo/electrochemical applications. This review provides a historical overview for the evolution of HTCS, along with an insightful discussion for the formation mechanism of self-assembly of HTCS during the sol-gel process. Key synthetic parameters including SDA, solvent, reaction temperature and water dosage are discussed for the size and morphology control of HTCS with predictable textural properties. Then, we describe the synthetic strategies of nanoporous TiO₂ and titanate spheres using various HTCS as self-templates. Here, the focus lies on the interactions between TiO₂ nanobuilding blocks with precursors or media at the solid/liquid and solid/solid interfaces, the concurrent phase transitions, and the microstructural and morphological evolutions. Selective formation of crystal phase and internal structures (e.g., solid, hollow, core-shell, yolk-shell) are discussed by manipulating the crystallization kinetics. To further elucidate the composition-structure-property-performance relationship for the resulting nanoporous TiO₂ and titanate spheres, their applications in photo(electro)catalysis, mesoscopic solar cells, and lithium-ion batteries are scrutinized. Finally, we share opinions on key challenges and perspectives for the future controllable preparation, formation mechanisms, and applications of HTCS and their crystalline derivatives.

Keywords: Lithium-ion batteries; Mesoscopic solar cells; Self-assembly; Semiconductor photocatalysis; Sol-gel process; TiO(2).

Publication types

Review