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Abstract Surface chemistry and core composition of 2D MXenes play a major role in their interfacial properties, but the determination and quantification of their bonding environments remain challenging. X‐ray Photoelectron Spectroscopy (XPS) is a method of choice that is broadly utilized but is often hindered by large uncertainties and systematic bias due to adsorbed species such as adventitious carbon or etching residues. In this work, energy‐dependent XPS and depth profile modeling of the Ti₃C₂T_xMXene surface are employed to differentiate the contributions from the MXene and the adsorbed species, thereby increasing the accuracy of quantification. In comparison, uncorrected lab‐based XPS suffers from a systematic overestimation of Ti vacancies by 7% and an underestimation of terminal atoms, particularly F, by as much as 15%. Interestingly, it is found that a simple inelastic mean free path correction is sufficient to address the issue and reveals extremely low defects in Ti₃C₂T_xMXene synthesized using the HF/HCl etching route. Soft X‐ray Absorption Spectroscopy (XAS), supported by Density Functional Theory (DFT) calculations, also demonstrates a high chemical sensitivity of the surface terminations. This work provides novel insights into XPS quantification and the use of XAS for probing the carbide core and surface chemistry of Ti₃C₂T_xMXenes. 

Abstract MXenes are promising passive components that enable lithium‐sulfur batteries (LSBs) by effectively trapping lithium polysulfides (LiPSs) and facilitating surface‐mediated redox reactions. Despite numerous studies highlighting the potential of MXenes in LSBs, there are no systematic studies of MXenes’ composition influence on polysulfide adsorption, which is foundational to their applications in LSB. Here, a comprehensive investigation of LiPS adsorption on seven MXenes with varying chemistries (Ti₂CT_x, Ti₃C₂T_x, Ti₃CNT_x, Mo₂TiC₂T_x, V₂CT_x, Nb₂CT_x, and Nb₄C₃T_x), utilizing optical and analytical spectroscopic methods is performed. This work reports on the influence of polysulfide concentration, interaction time, and MXenes’ chemistry (transition metal layer, carbide and carbonitride inner layer, surface terminations and structure) on the amount of adsorbed LiPSs and the adsorption mechanism. These findings reveal the formation of insoluble thiosulfate and polythionate complex species on the surfaces of all tested MXenes. Furthermore, the selective adsorption of lithium and sulfur, and the extent of conversion of the adsorbed species on MXenes varied based on their chemistry. For instance, Ti₂CT_xexhibits a strong tendency to adsorb lithium ions, while Mo₂TiC₂T_xis effective in trapping sulfur by forming long‐chain polythionates. The latter demonstrates a significant conversion of intermediate polysulfides into low‐order species. This study offers valuable guidance for the informed selection of MXenes in various functional components benefiting the future development of high‐performance LSBs.