3.6 Selectivity and thermostability of filtrated
TM2@sitex (x = 1, 2, 3, 4) systems
For eNRR performance in many studies, the competitive hydrogen evolution
reaction (HER) is the major hamper for ammonia yield. Thus, it is
necessary to compare N2 and H atom adsorption strength.
As depicted in Figure 7 , for all the selected systems, the
Gibbs free energy of *N2 is smaller than the
corresponding *H (mean the ΔG*N2 is more negative) and
can be regarded as efficient adsorption of N2, thus
inhibiting the competitive HER. Therefore, the
Ru2@site1,
W2@site2, and
W2@site4 may not be suitable for the
eNRR of the HER competition. Therefore, they are excluded from eNRR
exploration. Among the rest systems with high activity eNRR performance,
high stability is required for
Mn2@site1,
Co2@site2,
Os2@site3,
V2@site4, and
Cr2@site4 systems. Herein, the AIMD
simulation is performed at 300 K for 9 ps within a step of 1.5 fs are
employed. As shown in Figure 7 (b)-(f) , after simulation, the
structures of the selected systems are well maintained, meaning that the
systems chosen could keep their geometry under 300 K. At the same time,
the changes in temperature and energy are slightly, further revealing
the thermostability of the selected systems. Thus, the
Mn2@site1,
Co2@site2,
Os2@site3,
V2@site4, and
Cr2@site4 would keep stable during the
eNRR process.