Excited-State N2 Dissociation Pathway on Fe-Functionalized Au
Excited-State N2 Dissociation Pathway on Fe-Functionalized Au
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DOI：
10.1021/jacs.6b12301
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发表时间：
2017-03-29
影响因子：
15
通讯作者：
Carter, Emily A.
中科院分区：
文献类型：
--
作者：
Martirez, John Mark P.;Carter, Emily A.
局域表面等离子体共振(LSPR)提供了在强等离子体金属纳米颗粒表面进行光激活化学催化的可能性。这项技术依赖于在LSPR最终衰变后通过能量转移获得的低势垒键形成和/或解离途径。这些衰变过程与化学轨迹(核运动、电荷转移、系间交叉等)之间的耦合。规定了这些替代(可能较低的势垒)激发态通道的可用性。由N-2和H-2合成NH3的Haber Bosch方法是众所周知的能源密集型方法。这是因为尽管在环境温度和压力下，整个反应在热力学上是有利的，但N-2很难解离。LSPRs可以通过诱导共振电子激发来改善N-2的解离动力学。在这项工作中，我们利用嵌入密度泛函嵌入理论的n电子价二阶微扰理论，计算了N-2在Fe掺杂Au(111)表面上的激发态势能面。这种金属合金可以同时利用Au的较强的LSPR和Fe对N-2分解的催化活性。基态解离活化能为4.74 eV/N，Fe为表面活性中心。连续的共振能量转移(RET)可能是由于许多电子激发态的存在，这些电子激发态具有来自金属表面的中等能量，它们可能耦合到由Fe掺杂和吸附分子诱导的态，并且激发态之间的交叉可以有效地将解离势垒降低到1.33 eV。我们的工作表明，阻止化学反应的巨大能量障碍可以通过促进原本困难的化学过程的多个RET来克服。
Localized surface plasmon resonances (LSPRs) offer the possibility of light-activated chemical catalysis on surfaces of strongly plasmonic metal nanoparticles. This technology relies on lower-barrier bond formation and/or dissociation routes made available through energy transfer following the eventual decay of LSPRs. The coupling between these decay processes and a chemical trajectory (nuclear motion, charge-transfer, intersystem crossing, etc.) dictates the availability of these alternative (possibly lower barrier) excited-state channels. The Haber Bosch method of NH3 synthesis from N-2 and H-2 is notoriously energy intensive. This is due to the difficulty of N-2 dissociation despite the overall reaction being thermodynamically favorable at ambient temperatures and pressures. LSPRs may provide means to improve the kinetics of N-2 dissociation via induced resonance electronic excitation. In this work, we calculate, via embedded n-electron valence second-order perturbation theory within the density functional embedding theory, the excited-state potential energy surfaces for dissociation of N-2 on an Fe-doped Au(111) surface. This metal alloy may take advantage simultaneously of the strong LSPR of Au and the catalytic activity of Fe toward N-2 dissociation. We find the ground-state dissociation activation energy to be 4.74 eV/N, with Fe as the active site on the surface. Consecutive resonance energy transfers (RETs) may be accessed due to the availability of many electronically excited states with intermediate energies arising from the metal surface that may couple to states induced by the Fe-dopant and the adsorbate molecule, and crossing between excited states may effectively lower the dissociation barrier to 1.33 eV. Our work illustrates that large energetic barriers, prohibitive toward chemical reaction, may be overcome through multiple RETs facilitating an otherwise difficult chemical process.