The pursuit of high-performance two-dimensional (2D) materials for energy applications has traditionally focused on exfoliating layered van der Waals solids. However, a significant portion of promising 2D compounds exist in non-van der Waals bulk structures, where interlayer interactions are dominated by strong ionic or covalent bonding rather than weak van der Waals forces. This poses a challenge for conventional mechanical or chemical exfoliation techniques. In this work, we overcome this limitation by introducing a computational strategy to predict and identify stable, metallic 2D materials—specifically anti-MXenes—derived from such non-van der Waals precursors.
Anti-MXenes are defined by their unique atomic stacking: one transition metal (M) layer is sandwiched between two nonmetal (X) layers, forming an MX₂-like structure that is structurally inverted compared to MXenes (Mₙ₊₁Xₙ). These materials originate from KFe₂Se₂-type non-van der Waals bulks, where neighboring 2D sublayers are held together by ionic interactions. Despite the absence of weak interlayer forces, we demonstrate that these materials can be computationally extracted and stabilized as freestanding 2D monolayers through careful screening based on thermodynamic and dynamic stability criteria.
Using the Materials Project database, we initially retrieved 2575 AM₂X₂ compounds with I4/mmm space group symmetry, from which 79 distinct anti-MXene candidates were derived after removing the A cation. Subsequent DFT-based evaluations confirmed that 24 of these candidates possess robust stability across multiple dimensions: they exhibit negative cohesive energies (Ecoh < 0), no imaginary phonon frequencies (indicating dynamical stability), positive elastic constants satisfying mechanical stability conditions, and structural integrity during ab initio molecular dynamics (AIMD) simulations at 374 K for 20 ps. These results confirm that these anti-MXenes are viable targets for experimental realization. A key feature of these materials is their intrinsic metallicity. Unlike semiconducting 1H-MoS₂, which suffers from poor charge transport due to its band gap (~1.8 eV), all 24 stable anti-MXenes display metallic electronic structures. Their Fermi level intersects multiple bands originating from d-orbitals of transition metals and p-orbitals of nonmetals, enabling efficient electron conduction essential for electrochemical reactions.168555-66-6 supplier This property is attributed to the tetrahedral coordination of M atoms and enhanced M/X ratio, which facilitates orbital overlap and delocalized electron states.168555-66-6 supplier
The catalytic potential of anti-MXenes was assessed for hydrogen evolution reaction (HER) under varying hydrogen coverages.PMID:30855803 At low coverage (11.11%), CoP, CoB, and CuS exhibit near-zero ΔG*H values (-0.02, -0.03, and -0.05 eV, respectively), indicating excellent HER activity. Notably, CuS maintains favorable adsorption energetics across all H coverages—25%, 50%, and 100%—with ΔG*H values of -0.08, 0.02, and 0.05 eV, respectively. This broad applicability stems from the uniform distribution of tetracoordinated sulfur atoms across the basal plane, resulting in a high density of active sites (1.33 × 10¹⁹ site/m²). In contrast, other anti-MXenes like FeB and CoSi show optimal performance only at specific coverages, highlighting tunable catalytic behavior based on composition and surface geometry.
Beyond catalysis, CoB emerges as a highly promising anode material for lithium-ion batteries. It exhibits a low Li diffusion barrier (0.41 eV), allowing rapid ion transport, and achieves a theoretical capacity of 1099.44 mA h g⁻¹—over 2.9 times higher than graphite. The open circuit voltage remains within a safe range (0.35–1.38 V vs. Li⁺/Li), reducing the risk of lithium dendrite formation. Moreover, the metallic nature of CoB is preserved upon lithiation, ensuring long-term electrochemical stability.
This study establishes a reliable framework for the “computational exfoliation” of 2D materials from non-van der Waals hosts. By combining high-throughput screening with multi-scale stability analysis, we have expanded the landscape of accessible 2D materials beyond traditional layered crystals. The success of anti-MXenes in both electrocatalysis and energy storage underscores their versatility and positions them as next-generation functional materials. Future experimental synthesis efforts should target transformation pathways such as ion exchange or solid-state conversion, potentially unlocking new classes of high-performance 2D systems for sustainable energy technologies.MedChemExpress (MCE) offers a wide range of high-quality research chemicals and biochemicals (novel life-science reagents, reference compounds and natural compounds) for scientific use. We have professionally experienced and friendly staff to meet your needs. We are a competent and trustworthy partner for your research and scientific projects.Related websites: https://www.medchemexpress.com