THESIS
2020
xii, 58 pages : illustrations (chiefly color) ; 30 cm
Abstract
First-principles density functional theory (DFT) simulation is a commonly used method to study
the reaction mechanism of catalysts and provide explanations and guidance to experiments.
In this study, DFT simulation is used to investigate carbon-based non-precious metal
electrocatalysts for oxygen reduction reaction (ORR). It is found that ORR activity of Ce single
atom doped in N-doped porous carbon support is close to that of Pt/C. The ORR activation
energy barrier is 1.6 eV for CeN
4-C and 0.39 eV for Ce (OH) N
4-C, suggesting that the active
site may be partially blocked by OH. In another study, the results of DFT indicate that the
activation energy barrier of pyridinic N in metal-free N doped graphene is much lower than that
of graphene. This indicates that the former one is t...[
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First-principles density functional theory (DFT) simulation is a commonly used method to study
the reaction mechanism of catalysts and provide explanations and guidance to experiments.
In this study, DFT simulation is used to investigate carbon-based non-precious metal
electrocatalysts for oxygen reduction reaction (ORR). It is found that ORR activity of Ce single
atom doped in N-doped porous carbon support is close to that of Pt/C. The ORR activation
energy barrier is 1.6 eV for CeN
4-C and 0.39 eV for Ce (OH) N
4-C, suggesting that the active
site may be partially blocked by OH. In another study, the results of DFT indicate that the
activation energy barrier of pyridinic N in metal-free N doped graphene is much lower than that
of graphene. This indicates that the former one is the main active site.
The results of DFT illustrate that TaB, ZrB, and Ta
1/2Zr
1/2B can be used as good electrocatalysts
for nitrogen reduction reaction (NRR). The calculated overpotentials of TaB, ZrB, and
Ta
1/2Zr
1/2B are 0.67, 0.66, and 0.63 eV, respectively. The hydrogen evolution reaction kinetics
of TaB and ZrB are less competitive than that of NRR with higher energy barriers.
DFT calculation explains that experiments of covering Zn-MOF-74 onto ZIF-8@Pd increase
the probability of selectively hydrogenating C=C bond from 91% to 99%. All calculations show
that Pd nanoparticles have intrinsic hydrogenation selectivity for C=C bond over -NO
2 group.
Meanwhile, ZIF-8 and Zn-MOF-74 both facilitate the selective hydrogenation of C=C bonds.
However, Zn-MOF-74@Pd has better selective property than ZIF-8@Pd owing to the
coordinated unsaturated sites (CUSs).
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