Double Transition Metal Carbides MXenes (D-MXenes) as Promising Electrocatalysts for Hydrogen Reduction Reaction: Ab Initio Calculations

Abstract

Double-transition-metal MXenes (D-MXenes) have been widely pursued in the advancement of the renewable energy storage technology in recent years. In this work, the hydrogen evolution reaction (HER) catalytic mechanism of several oxygen-terminated D-MXenes with the chemical formula of M′2M″C2O2 (M′ = Mo, Cr; M″ = Ti, V, Nb, Ta) is theoretically studied. For comparison, the corresponding monometallic MXenes (M-MXenes, M′3C2O2) are fairly compared by means of the density functional theory calculations. Based on our theoretical results, the HER performance of M-MXenes can be improved by constructing a “sandwich-like” ordered D-MXene configuration. Moreover, the HER performance of Mo-based D-MXenes (Mo2M″C2O2) is superior to that of Cr-based D-MXenes (Cr2M″C2O2), which highlights that the HER activity of Mo2VC2O2 and Mo2NbC2O2 is better than that of Pt(111). This work not only unravels the HER mechanism of D-MXenes (M′2M″C2O2) but also paves the way in designing emergent MXene-based HER electrocatalysts with high efficiency.

Ordered Double Transition Metal MXenes

“…Li et al. investigated the HER activities of eight ordered double transition metal MXenes and two corresponding monometallic MXene (M‐MXene) through DFT calculations [27] . They postulated that the performance of M‐MXenes could be enhanced by constructing a sandwich‐like ordered double transition metal MXene wherein the internal metal layers of M‐MXenes are incorporated with other transition metal atoms.…”

“…Li et al investigated the HER activities of eight ordered double transition metal MXenes and two corresponding monometallic MXene (M-MXene) through DFT calculations. [27] They postulated that the performance of M-MXenes could be enhanced by constructing a sandwich-like ordered double transition metal MXene wherein the internal metal layers of M-MXenes are incorporated with other transition metal atoms. The ΔG H value of M-MXenes is larger than Mo-based ordered double transition metal MXenes s. Also, the Mo-based MXenes had superior performance than the Cr-based ones, as seen in [27] the volcano map shown in Figure 6c.…”

“…[27] They postulated that the performance of M-MXenes could be enhanced by constructing a sandwich-like ordered double transition metal MXene wherein the internal metal layers of M-MXenes are incorporated with other transition metal atoms. The ΔG H value of M-MXenes is larger than Mo-based ordered double transition metal MXenes s. Also, the Mo-based MXenes had superior performance than the Cr-based ones, as seen in [27] the volcano map shown in Figure 6c. The O-functional groups of the ordered double transition metal MXenes adsorbed onto the C-atom at the outmost layer of the MXene exhibited better HER performance than the ones with O-functional groups adsorbed above the metal atomic layer of the innermost layer of the MXene.…”

“…[26] © Elsevier. (c) HER volcano map of Cr 2 M''C 2 O 2 and Mo 2 M''C 2 O 2 and (d) enlarged detail at the vicinity of the peak [27].…”

Potential of MXene-Based Heterostructures for Energy Conversion and Storage

“…It is urgent to develop HF-free mild synthesis methods , and efficient modification by surface engineering , interface engineering, , and optimizing the existing MXene species. Ab initio calculations − are highly encouraged for the discovery of novel MXene materials. In addition, band engineering can be predicted for the MXene-based heterostructures. − …”