Hydrogen Evolution Reaction on the Single-Shell Carbon-Encapsulated Iron Nanoparticle: A Density Functional Theory Insight
Hydrogen Evolution Reaction on the Single-Shell Carbon-Encapsulated Iron Nanoparticle: A Density Functional Theory Insight
复制标题
DOI：
10.1021/acs.jpcc.9b01041
复制
发表时间：
2019-06-06
影响因子：
3.7
通讯作者：
Laasonen, Kari
中科院分区：
文献类型：
--
作者：
Cipa-Karhu, Geraldine;Pakkanen, Olli J.;Laasonen, Kari
由于铂的昂贵和稀缺性，无铂催化剂在析氢反应中的应用是目前研究的热点。单壳碳包封铁纳米颗粒（SCEIN）的实验已经证明了与最好的Pt催化剂相当的HER催化效率。然而，缺乏对结构效率的理解。我们对SCEIN的一个现实模型，即Fe-SS@C-240，进行了从头算密度泛函理论计算，以阐明SCEIN的催化性能，并研究了C-60和C-240富勒烯进行比较。在这些体系上实现了热力学自由能方法（Δ G（H））和动力学（Volmer-Heyrovsky/Tafel反应势垒E-a）计算。我们的计算证明了Fe-SS在增强C-240上的氢键结合方面具有关键作用。Volmer-Heyrovsky是优选的机理，Heyrovsky是E-a > 1 eV的限制反应。碳表面的非零覆盖增强了Δ G（H）而不显著影响E-a。由于Δ G（H）-至-E-a关系是非线性的，因此我们提出了一种基于DDEC 6键级（BO）方法的计算有效策略，以在任何计算之前预先选择潜在的HER位点。E-a被证明是高度位点依赖性和（C-Fe）BO依赖性的，导致Fe-SS@C-240的高度非均相催化能力。然后可以通过处理表面覆盖来优化Delta G（H）/E-a最佳对。
Platinum (Pt)-free catalysts for the hydrogen evolution reaction (HER) is currently a blooming research topic in view of the high cost and scarcity of Pt. Experiments on single-shell carbon-encapsulated iron nanoparticles (SCEINs) have proven comparable HER catalytic efficiency with the best Pt catalyst. However, an understanding of the structure-to efficiency is missing. We performed ab initio density functional theory calculations on a realistic model of SCEINs, namely Fe-SS@C-240, to shed light on the catalytic properties of SCEINs and studied C-60 and C-240 fullerenes for comparison. Both the thermodynamic free energy approach (Delta G(H)) and kinetic (Volmer-Heyrovsky/Tafel reaction barrier E-a) calculations were realized on these systems. Our calculations proved that Fe-SS has a key role in enhancing the hydrogen binding on C-240. Volmer-Heyrovsky is the preferred mechanism, Heyrovsky being the limiting reaction with E-a > 1 eV. Non-zero coverage of the carbon surface enhances Delta G(H) without significantly affecting E-a. Because the Delta G(H)-to-E-a relationship is nonlinear, we proposed a computationally efficient strategy based on the DDEC6 bond order (BO) method to preselect potential HER sites before any calculations. E-a proved to be highly site- and (C-Fe) BO-dependent, leading to the highly heterogeneous catalytic ability of Fe-SS@C-240. Delta G(H)/E-a best pairs can then be optimized by playing with the surface coverage.