Hexagonal MBenes-Supported Single Atom as Electrocatalysts for the Nitrogen Reduction Reaction

Abstract

The electrocatalytic nitrogen reduction reaction (NRR) is currently constrained by sluggish reaction kinetics and poor selectivity because of the difficulties in activating inert N≡N triple bonds and the existence of competing hydrogen evolution reaction (HER). Therefore, electrocatalysts with high activity, selectivity, and stability are highly desired. Herein, by means of first-principles calculations, we investigated the electrocatalytic NRR performance of a series of transition metal atoms (e.g., 3d, 4d, and 5d) embedded in defective hexagonal MBene nanosheets [ h- Zr(Hf) 2 B 2 O 2 ] and identified that h- Zr(Hf) 2 B 2 O 2 could be an excellent platform for electrocatalytic NRR. On the basis of our proposed screening criteria, 16 candidates are efficiently selected out from 50 systems, among which, Zr 2 B 2 O 2 -Cr stands out with high selectivity to NRR against HER and the ultralow limiting potential (−0.10 V). The value is much lower than that of the well-established stepped Ru(0001) surface (−0.43 V). The origin of the high activity toward NRR is attributed to the synergistic effect of the single atom (SA) and the M atoms in the substrate. More impressively, a composition descriptor is further proposed on the basis of the inherent characteristics of the catalysts [number of valence electrons of SA and electronegativity of the SA and Zr(Hf) atoms], which helps to better predict the catalytic performance. Our work not only contributes to the development of highly efficient NRR electrocatalysts but also extend the application of h -MBenes in electrocatalysis.

h-MBenes (M/B = 1:1) as Promising Electrocatalysts for Nitrogen Reduction Reaction: A Theoretical Study

“…All calculations were performed using the spin-polarized density functional theory (DFT) method based on the projector augmented wave (PAW) approach, as implemented in the Vienna Ab inito Simulation Package (VASP). , The exchange–correlation energy was modeled using the Perdew–Burke–Ernzerhof (PBE) functional within the generalized gradient approximation (GGA) framework. This choice was made based on the proven accuracy of the PBE functional in calculating Gibbs free energy . An energy cutoff of 550 eV was used for the plane-wave basis set.…”

“…For example, it has been demonstrated that MoC 2, Mo 2 B 2 , and Fe 2 B 2 exhibit outstanding electrochemical properties. Additionally, MBenes serve as an ideal matrix for supporting signal-atom catalysts. , However, research on MBenes in the field of electrochemistry is still in its early stages , and has primarily focused on orthorhombic MAB. , Moreover, although theoretical calculations show that MBenes have a great potential in electrochemical catalysis, how to obtain MBenes from their parent material MAB phases remains a great challenge …”

h-MBenes: Promising Two-Dimensional Material Family for Room-Temperature Antiferromagnetic and Hydrogen Evolution Reaction Applications

“…29,36 However, the discovery of h-MBenes is still limited, and currently only four h-MBenes (ZrB, HfB, TiB, and Hf 2 B) have been theoretically identified as promising candidates for applications in metal-ion batteries and electrocatalysis with transition-metal modifications. [17][18][19]24,3037 These initial successful studies have inspired researchers to further explore the intrinsic properties and potential applications of h-MBenes in more depth.…”

“…In recent years, there has been a growing interest in the ternary laminate transitional metal borides (MAB phases), which are analogous to MAX phases, due to their potential for selective etching into 2D counterparts known as MBenes. − Among these, 2D orthorhombic transition-metal borides ( ort -MBenes) have emerged as promising candidates for applications in Li-ion batteries (LIB) electrodes and electrocatalysis materials since 2017, leading to a growing emphasis on the experimental and theoretical investigation of MBenes in energy storage, magnetic devices, and catalysts. − However, the selective etching of A layers from orthorhombic MAB ( ort -MAB) phases poses challenges. Currently, only two ort -MAB phases, MoAlB and Cr 2 AlB 2 , have been investigated as precursors for the synthesis of ort -MBenes (MoB and CrB). ,− In 2019, our research group successfully predicted and synthesized the first hexagonal ternary laminate MAB ( h -MAB) phase, Ti 2 InB 2 .…”

“…Due to their unique graphene-like boron layer, large specific surface area, excellent electrical conductivity, and robust structural stability, h -MBenes show promise for electrocatalysis applications. Meanwhile, MBenes are promising candidate materials for spintronic applications due to the potential for intrinsic magnetic coupling induced by the unpaired d or f electrons of transition-metal atoms. , However, the discovery of h -MBenes is still limited, and currently only four h -MBenes (ZrB, HfB, TiB, and Hf 2 B) have been theoretically identified as promising candidates for applications in metal-ion batteries and electrocatalysis with transition-metal modifications. − ,, These initial successful studies have inspired researchers to further explore the intrinsic properties and potential applications of h -MBenes in more depth.…”