TY - JOUR
T1 - Tunable Ti3C2TxMXene-Derived TiO2Nanocrystals at Controlled pH and Temperature
AU - Chae, Ari
AU - Doo, Sehyun
AU - Kim, Daesin
AU - Ko, Tae Yun
AU - Oh, Taegon
AU - Kim, Seon Joon
AU - Koh, Dong Yeun
AU - Koo, Chong Min
N1 - Funding Information:
This work was supported by a grant from the Basic Science Research Program (Nos. 2022R1A2C3006227 and 2021M3H4A1A03047327) through the National Research Foundation of Korea, funded by the Ministry of Science, ICT and Future Planning (MSIT), and the Industrial Strategic Technology Development Program (No. 20020855) funded by the Ministry of Trade, Industry and Energy, Republic of Korea. This work was supported by the National Research Council of Science & Technology (NST) grant by the Korea government (MSIT) (No. CRC22031-000). This work was partially supported by a start-up fund (No. S-2022-0096-000) from Sungkyunkwan University.
Publisher Copyright:
© 2022 American Chemical Society.
PY - 2022/10/18
Y1 - 2022/10/18
N2 - While two-dimensional (2D) Ti3C2Tx MXene in aqueous dispersions spontaneously oxidizes into titanium dioxide (TiO2) nanocrystals, the crystallization mechanism has not been comprehensively understood and the resultant crystal structures are not controlled among three representative polymorphs: anatase, rutile, and brookite. In this study, such control on the lattice structures and domain sizes of the MXene-derived TiO2 crystallites is demonstrated by means of the oxidation conditions, pH, and temperature (3.0-11.0 and 20-100 °C, respectively). It is observed that the formation of anatase phase is preferred against rutile phase in more basic and hotter oxidizing solutions, and even 100% anatase can be obtained at pH 11.0 and 100 °C. At lower pH and temperature, the portion of rutile phase increases such that it reaches ∼70% at pH 3 and 20 °C. Under certain circumstances, small portion of brookite phase is also observed. Smaller domain sizes of both anatase and rutile phases are observed in more basic oxidizing solutions and at lower temperatures. Based on these experimental results, we propose the crystallization mechanism in which the oxidative dissociation of Ti3C2Tx first produces Ti ions as the intermediate state, and they bind to abundant oxygen in the aqueous dispersions, and nucleate and crystallize into TiO2.
AB - While two-dimensional (2D) Ti3C2Tx MXene in aqueous dispersions spontaneously oxidizes into titanium dioxide (TiO2) nanocrystals, the crystallization mechanism has not been comprehensively understood and the resultant crystal structures are not controlled among three representative polymorphs: anatase, rutile, and brookite. In this study, such control on the lattice structures and domain sizes of the MXene-derived TiO2 crystallites is demonstrated by means of the oxidation conditions, pH, and temperature (3.0-11.0 and 20-100 °C, respectively). It is observed that the formation of anatase phase is preferred against rutile phase in more basic and hotter oxidizing solutions, and even 100% anatase can be obtained at pH 11.0 and 100 °C. At lower pH and temperature, the portion of rutile phase increases such that it reaches ∼70% at pH 3 and 20 °C. Under certain circumstances, small portion of brookite phase is also observed. Smaller domain sizes of both anatase and rutile phases are observed in more basic oxidizing solutions and at lower temperatures. Based on these experimental results, we propose the crystallization mechanism in which the oxidative dissociation of Ti3C2Tx first produces Ti ions as the intermediate state, and they bind to abundant oxygen in the aqueous dispersions, and nucleate and crystallize into TiO2.
UR - http://www.scopus.com/inward/record.url?scp=85139863784&partnerID=8YFLogxK
U2 - 10.1021/acs.langmuir.2c02110
DO - 10.1021/acs.langmuir.2c02110
M3 - Article
C2 - 36206453
AN - SCOPUS:85139863784
VL - 38
SP - 12657
EP - 12665
JO - Langmuir
JF - Langmuir
SN - 0743-7463
IS - 41
ER -