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Page 4 of 25 Meng et al. J. Mater. Inf. 2025, 5, 3 https://dx.doi.org/10.20517/jmi.2024.74

Figure 2. (A) Schematic illustration of five possible mechanisms (consecutive, enzymatic, alternative, distal, and mixed) for NRR.
Reprinted with permission from Ref. [22] . Copyright © 2021, American Chemical Society; (B) MvK mechanism for NRR. Reprinted with
permission from Ref. [23] . Copyright © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim; (C) Enzyme-distal mechanism for NRR.
Reprinted with permission from Ref. [24] . Copyright © 2021 Dalian Institute of Chemical Physics, the Chinese Academy of Sciences; (D)
N dissociation mechanism under confined dual sites (pink and blue spheres denote metal and nitrogen atoms, respectively; IS, TS, and
2
FS denote initial, transition, and final states, respectively). Reprinted with permission from Ref. [25] . Copyright © 2024 National Academy
of Sciences; (E) Reaction mechanism for NRR on Rh surface. Reprinted with permission from Ref. [26] . Copyright © 2020 Wiley-VCH
Verlag GmbH & Co. KGaA, Weinheim; (F) Schematic of surface-hydrogenation mechanism for NRR on noble-metal-based catalysts.
Reprinted with permission from Ref. [27] . Copyright © 2019 American Chemical Society. NRR: Nitrogen reduction reaction; MvK: Mars-
van-Krevelen; IS: initial state; TS: transition state; FS: final state.

SACS TOWARDS NRR
Mo-based SACs
In nature, nitrogenase enzymes convert N to NH under mild conditions (< 40 °C, atmospheric
2
3
pressure) . Unfortunately, biological nitrogenases are significantly influenced by environmental factors,
[31]
leading to instability in nitrogen fixation and limiting their large-scale applications. The active center of
nitrogenase systems comprises clusters of different metal atoms, such as Fe-Mo, V-Fe, and Fe-Fe
nitrogenases. Naturally, bio-inspired catalyst structures containing Mo, Fe, or V atoms deposited on two-
dimensional (2D) nanomaterials have been extensively explored for their catalytic performance under mild
conditions.

Recent reports on Mo/Fe/V-based SACs towards NRR, calculated using first-principles methods, are
summarized in Table 1. Among these systems, the Fe-Mo nitrogenase systems have received the most
attention, leading to the design of various Mo-containing catalysts for NRR. Thus, in this subsection, we
focus on Mo-based SACs, highlighting representative catalysts.

Zhao et al. systematically investigated the potential of a series of single TM atoms (Sc ~ Zn, Nb, Mo, Rh, Ru,
Pd, and Ag) anchored on the BN monolayers with a boron monovacancy (TM-BN) and on C N monolayer
2
(TM@C N) as NRR catalysts by density functional theory (DFT) calculations. The results showed that Mo-
2
BN [Figure 3A] and Mo@C N are promising NRR catalysts with low U of -0.35 and -0.17 V,
L
2
respectively [32,33] . In addition, Zhao et al. systematically studied the activity of single atoms of Sc, Ti, V, Cr,
Mn, Fe, Co, Ni, Cu, Mo, Rh, and Ru embedded on MoS nanosheets with S-vacancy defects (TM/MoS ) as
2
2
NRR catalysts. It is indicated that Mo/MoS nanosheet exhibits the highest NRR activity due to the high
2
stability of N H intermediates . These findings suggest that the choice of substrate material significantly
*
[34]
2