Al-Temimy Ameer, Prenger Kaitlyn, Golnak Ronny, Lounasvuori Mailis, Naguib Michael, Petit Tristan
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Str. 15, 12489 Berlin, Germany.
Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
ACS Appl Mater Interfaces. 2020 Apr 1;12(13):15087-15094. doi: 10.1021/acsami.9b22122. Epub 2020 Mar 17.
Intercalation in TiCT MXene is essential for a diverse set of applications such as water purification, desalination, electrochemical energy storage, and sensing. The interlayer spacing between the TiCT nanosheets can be controlled by cation intercalation; however, the impact of intercalation on the TiCT MXene chemical and electronic structures is not well understood. Herein, we characterized the electronic structure of pristine, Li-, Na-, K-, and Mg-intercalated TiCT MXenes dispersed initially in water and 10 mM sulfuric acid (HSO) using X-ray absorption spectroscopy (XAS). The cation intercalation is found to dramatically influence the chemical environment of Ti atoms. The Ti oxidation of the MXene increases progressively upon intercalation of cations of larger sizes after drying in air, while interestingly a low Ti oxidation is observed for all intercalated MXenes after dispersion in diluted HSO. In situ XAS at the Ti L-edge was conducted during electrochemical oxidation to probe the changes in the Ti oxidation state in the presence of different cations in HSO aqueous electrolyte. By applying the sensitivity of the Ti L-edge to probe the oxidation state of Ti atoms, we demonstrate that cation-intercalation and HSO environment significantly alter the TiCT surface chemistry.
TiCT MXene的插层对于多种应用至关重要，如水净化、脱盐、电化学储能和传感。TiCT纳米片之间的层间距可通过阳离子插层来控制；然而，插层对TiCT MXene化学和电子结构的影响尚未得到很好的理解。在此，我们使用X射线吸收光谱（XAS）对最初分散在水和10 mM硫酸（HSO）中的原始、锂、钠、钾和镁插层的TiCT MXene的电子结构进行了表征。发现阳离子插层会显著影响Ti原子的化学环境。在空气中干燥后，随着较大尺寸阳离子的插层，MXene的Ti氧化态逐渐增加，而有趣的是，在稀释的HSO中分散后，所有插层的MXene都观察到低Ti氧化态。在电化学氧化过程中进行了Ti L边的原位XAS，以探测在HSO水性电解质中存在不同阳离子时Ti氧化态的变化。通过利用Ti L边对探测Ti原子氧化态的敏感性，我们证明阳离子插层和HSO环境会显著改变TiCT的表面化学性质。
