Dopamine Functionalized TiO2 1D Lepidocrocite Mesoporous Particles As a Sulfur Host

Abstract

Lithium sulfur batteries are attractive because of their high specific capacities. However, a variety of issues, chiefly polysulfides and the polysulfide shuttle still hinder their development. In our past work we demonstrated a new form of titania-based nanomaterials which we labelled 1 dimensional lepidocrocite nanofilaments (1DLs) as a sulfur (S) host for Li-S batteries1. 1DL is synthesized using a facile bottom-up scalable reaction, directly from commercial 3D bulk solids at ambient pressures and near ambient temperatures2. Moreover, these materials self-assemble into a plethora of microstructures – from individual 1D nanofilaments 5x7 Å2 in cross-section to 2D flakes to mesoscopic particles, all comprised of 1DL - depending on the synthesis and washing parameters. The multitude of structures allows for a variety of applications like electrocatalysis and hydrogen production3. Here we introduce a new structure of 1DLs - mesoporous particles - as S hosts. We further show that by employing a facile, aqueous, 1-step surface functionalization with dopamine – confirmed through changes in the FTIR peaks and an increase in the d-spacing in XRD (inst in Fig 1b) – we increase their interaction with S. The surface functionalization results in a reduction of the 1DL bandgap energy, Eg, to ~1.84 eV, which is a ≈ 50% reduction over un-functionalized 1DL. Additionally, the surface functionalization renders a more conformal coating of S on the 1DL, leading to increased S utilization and interaction with the 1DL, seen in a 20% reduction in of polysulfide shuttle current and 750 mAh.gs -1 at 0.5 C at a loading of 2 mg.cm-2 (seen in Fig 1a and 1b). This is further seen in the increased interactions of the thiosulfate species and Lewis acid-base interactions, shown in our prior work with S and 1DL.References Cardoza, N. A.; Badr, H. O.; Pereira, R.; Barsoum, M. W.; Kalra, V. One-Dimensional, Titania Lepidocrocite-Based Nanofilaments and Their Polysulfide Anchoring Capabilities in Lithium–Sulfur Batteries. ACS Appl. Mater. Interfaces 2023, 15 (44), 50973–50980.Badr, H. O.; Cope, J.; Kono, T.; Torita, T.; Lagunas, F.; Castiel, E.; Klie, R. F.; Barsoum, M. W. Titanium Oxide-Based 1D Nanofilaments, 2D Sheets, and Mesoporous Particles: Synthesis, Characterization, and Ion Intercalation. Matter 2023, 6 (10), 3538–3554.Badr, H. O.; Natu, V.; Neațu, Ștefan; Neațu, F.; Kuncser, A.; Rostas, A. M.; Racey, M.; Barsoum, M. W.; Florea, M. Photo-Stable, 1D-Nanofilaments TiO2-Based Lepidocrocite for Photocatalytic Hydrogen Production in Water-Methanol Mixtures. Matter 2023, 6 (9), 2853–2869. Figure 1