The Rapid Exfoliation and Subsequent Restacking of Layered Titanates Driven by an Acid–Base Reaction

Abstract

Two-dimensional (2D) (hydro)oxide materials, that is, nanosheets, enable the preparation of advanced 2D materials and devices. The general synthesis route of nanosheets involves exfoliating layered metal (hydro)oxide crystals. This exfoliation process is considered to be time-consuming, hindering their industrial-scale production. Based on in situ exfoliation studies on the protonated layered titanate H(1.07)Ti(1.73)O4⋅H2O (HTO), it is now shown that ion intercalation-assisted exfoliation driven by chemical reaction provides a viable and fast route to isolated nanosheets. Contrary to the general expectation, data indicate that direct exfoliation of HTO occurs within seconds after mixing of the reactants, instead of proceeding via a swollen state as previously thought. These findings reveal that ion intercalation-assisted exfoliation driven by chemical reaction is a promising exfoliation route for large-scale synthesis.

Tailoring Vanadium Dioxide Film Orientation Using Nanosheets: a Combined Microscopy, Diffraction, Transport, and Soft X‐Ray in Transmission Study

“…x H 2 O were obtained by treating with 2 m HNO 3 for 3 d and replacing new acid solution every day. The rapid exfoliation with TBAOH, which has been reported for H 1.07 Ti 1.73 O 4 .H 2 O was also observed for HNbWO 6 . x H 2 O. Full‐coverage TO and NWO nanosheet films were generated on Si substrates and Si 3 N 4 TEM grips using the LB method.…”

Ultrathin HNbWO6 nanosheets: facile synthesis and enhanced hydrogen evolution performance from photocatalytic water splitting

“…It is believed that the amine end of the TEOA tends to accept a proton from water because of the presence of lone electron pairs, generating [HN(CH 2 CH 2 OH) 3 between the neighboring layers offering this layered material for stripping. [33][34][35] We also demonstrated that this method was suitable to obtain HNbxTa1-xWO 6 (x=0.7, 0.5, 0.3, 0) ultrathin nanosheets (see Fig. S7), suggesting the generality of the protocol.…”

Advances in Ink‐Jet Printing of MnO2‐Nanosheet Based Pseudocapacitors

“…Copyright 2003, American Chemical Society; i) Mechanism of sheet exfoliation and restacking: 1) mixing protonated layered oxide with TAAOH, 2) annihilation of protons by OH − , 3) formation of nanosheets, 4) restacking into swollen state at high TAA + /H + ratio. Reproduced with permission . Copyright 2015, Wiley‐VCH; j) Schematic of strained MnO 2 nanosheet with Mn 4+ vacancies in the 2D crystallite, and surface Mn 3+ ions (indicated in green) residing above the crystallite plane.…”

“…In the second step of the exfoliation process, H x MnO 2 is reacted with a tetraalkylammonium (TAA) hydroxide, where alkyl = C n H 2 n +1 ( n = 1–4) . The intercalated protons are annihilated by acid‐base reaction with OH − . Ultimately, all protons are replaced by TAA + .…”