High-Throughput Screening of Sulfur Reduction Reaction Catalysts Utilizing Electronic Fingerprint Similarity

The catalytic performance is determined by the electronic structure near the Fermi level. This study presents an effective and simple screening descriptor, i.e., the one-dimensional density of states (1D-DOS) fingerprint similarity, to identify potential catalysts for the sulfur reduction reaction (SRR) in lithium–sulfur batteries. The Δ1D-DOS in relation to the benchmark W2CS2 was calculated. This method effectively distinguishes and identifies 30 potential candidates for the SRR from 420 types of MXenes. Further analysis of the Gibbs free energy profiles reveals that MXene candidates exhibit promising thermodynamic properties for SRR, with the protocol achieving an accuracy rate exceeding 93%. Based on the crystal orbital Hamilton population (COHP) and differential charge analysis, it is confirmed that the Δ1D-DOS could effectively differentiate the interaction between MXenes and lithium polysulfide (LiPS) intermediates. This study underscores the importance of the electronic fingerprint in catalytic performance and thus may pave a new way for future high-throughput material screening for energy storage applications

Unveiling the Critical Relationship between MXene Double-Layer Capacitance and Electronic Configuration

MXene, with highly tunable and controllable surface terminations, is an emerging electrode material for electric double-layer (EDL) capacitors used in electrochemical energy storage. However, the influence of alterations in the electronic configuration of MXene induced by modifications in functional groups on EDL capacitance remains elusive. Thus, an implicit self-consistent electrolyte model is developed to investigate the EDL capacitance and structure of Mo2CTx MXene as a function of electronic configuration at an atomic scale. We reveal a strong correlation between the electronic configurations of metal Mo in Mo2CTx MXene and its EDL capacitance, with the dz2 orbital of Mo perpendicular to the MXene surface playing a crucial role. The higher EDL capacitance and thinner EDL thickness primarily originate from a lower number of occupied electrons in the d orbitals (higher unoccupied d orbitals) and a larger d-band occupied center. Furthermore, this relationship can be further extended to the halogen termination of MXene. Notably, by manipulating the surface terminations, the electronic configurations (occupied and unoccupied orbitals) of Mo orbitals can be regulated, thus providing a facilitative way to control the EDL capacitance. The results show that the EDL capacitance depends not only on the electrode–electrolyte interfacial structure but also on the electronic configuration. These findings provide a solid foundation for regulating the structure and capacitance of the EDL of MXene from an electronic perspective, which could have significant implications for the development of advanced energy storage devices

X‑ray Insights into Formation of −O Functional Groups on MXenes: Two-Step Dehydrogenation of Adsorbed Water

Engineered MXene surfaces with more −O functional groups are feasible for realizing higher energy density due to their higher theoretical capacitance. However, there have been only a few explorations of this regulation mechanism. Investigating the formation source and mechanism is conducive to expanding the adjustment method from the top-down perspective. Herein, for the first time, the formation dynamics of −O functional groups on Mo2CTx are discovered as a two-step dehydrogenation of adsorbed water through in situ near-ambient-pressure X-ray photoelectron spectroscopy, further confirmed by ab initio molecular dynamics simulations. From this, the controllable substitution of −F functional groups with −O functional groups is achieved on Mo2CTx during electrochemical cycling in an aqueous electrolyte. The obtained Mo2CTx with rich −O groups exhibits a high capacitance of 163.2 F g –1 at 50 mV s –1, together with excellent stability. These results offer new insights toward engineering surface functional groups of MXenes for many specific applications

X‑ray Insights into Formation of −O Functional Groups on MXenes: Two-Step Dehydrogenation of Adsorbed Water

Engineered MXene surfaces with more −O functional groups are feasible for realizing higher energy density due to their higher theoretical capacitance. However, there have been only a few explorations of this regulation mechanism. Investigating the formation source and mechanism is conducive to expanding the adjustment method from the top-down perspective. Herein, for the first time, the formation dynamics of −O functional groups on Mo2CTx are discovered as a two-step dehydrogenation of adsorbed water through in situ near-ambient-pressure X-ray photoelectron spectroscopy, further confirmed by ab initio molecular dynamics simulations. From this, the controllable substitution of −F functional groups with −O functional groups is achieved on Mo2CTx during electrochemical cycling in an aqueous electrolyte. The obtained Mo2CTx with rich −O groups exhibits a high capacitance of 163.2 F g –1 at 50 mV s –1, together with excellent stability. These results offer new insights toward engineering surface functional groups of MXenes for many specific applications