Acetylacetone–sulfur polymer-derived sulfur/oxygen-doped porous carbons for co₂ capture and lithium–sulfur battery separator coatings

Abstract

Sulfur/oxygen-rich polymer-derived carbons are promising multifunctional materials; however, solvent-assisted strategies for transforming low-molecular-weight oxygenated liquids into solid carbonizable networks remain underexplored. Herein, acetylacetone was used as an oxygen-bearing liquid precursor in a DMSO-assisted acetylacetone–sulfur reaction to form an acetylacetone–sulfur polymer (AcAcPS), which was subsequently converted into sulfur/oxygen-containing porous carbons by CO₂ activation or NaCl templating. XRD, Raman, FTIR, XPS, solid-state ¹³C NMR, DSC, and electrochemical analyses supported the formation of a chemically transformed sulfur–organic network containing AcAc-derived carbonyl/enolic functionalities. The resulting CO₂-C and NaCl-C carbons retained high sulfur contents of approximately 20–22 wt% and low oxygen contents of 2–4 wt%, while exhibiting distinct microporous/ultramicroporous and micro/macroporous architectures, respectively. At 298 K and 0.15 bar, CO₂-C and NaCl-C exhibited CO₂ uptakes of 0.75 and 0.81 mmol g⁻¹, respectively, and retained 0.52 and 0.58 mmol g⁻¹ at 313 K. When used as Li–S separator-coating additives at only 12.5 wt% of the coating formulation, CO₂-C and NaCl-C delivered sulfur-mass-normalized recovery capacities of 870 and 879 mAh g⁻¹, respectively, after returning to 0.1 C following the 2 C rate step, exceeding the conductive-carbon-only coating. UV–Vis adsorption/permeation tests and DFT calculations indicate that sulfur-containing carbon sites enhance interactions with Li₂S₆, although electrochemical performance also depends on pore accessibility, particle agglomeration, coating morphology, electrical connectivity, and interfacial transport. Overall, this work demonstrates a DMSO-assisted ketone–sulfur route for transforming an oxygen-bearing liquid molecule into sulfur-rich porous carbons with dual functionality in post-combustion CO₂ capture and Li–S separator modification.