Fundamental Electrochemical Insights of Vertically Aligned Carbon Nanofiber Architecture as a Catalyst Support for ORR
Fundamental Electrochemical Insights of Vertically Aligned Carbon Nanofiber Architecture as a Catalyst Support for ORR
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DOI：
10.1149/1945-7111/ab86c1
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发表时间：
2020-04
影响因子：
3.9
通讯作者：
Ayyappan Elangovan;Jiayi Xu;Emery Brown;B. Liu;Jun Li
中科院分区：
文献类型：
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作者：
Ayyappan Elangovan;Jiayi Xu;Emery Brown;B. Liu;Jun Li
三维（3D）结构的碳载体在燃料电池催化剂方面受到了极大的关注。然而，复杂的结构使得使用传统的旋转盘电极（RDE）方法评估催化性能变得困难。本文报道了在垂直排列的碳纳米纤维（VACNF）阵列上使用离子束溅射 Pt 催化剂（Pt 负载量为 6.5–43 μg cm−2）进行氧还原反应（ORR）的系统研究，该阵列由圆锥形堆叠的石墨微结构组成。 RDE 研究表明，VACNF 的厚 3D 结构表现出增强的极限电流密度，这与传统薄膜催化剂的 Levich 方程不同。尽管如此，可以从此类系统的 RDE 实验中获得有用的信息。构建了代表 VACNF 的分子模型，以探索其作为 ORR 催化剂载体的能力。铂原子在 VACNF 的开放石墨边缘形成牢固的键，证实了 VACNF 在稳定 Pt 方面的作用。密度泛函理论 (DFT) 计算分别进一步阐明了裸 VACNF 和 Pt/VACNF 催化剂上的二电子和四电子 ORR 路径。此外，与基准 Pt/C 催化剂相比，Pt/VACNF 催化剂对甲醇氧化具有更强的耐受性，并且具有更高的从一氧化碳中毒中恢复的能力。这些结果为开发未来高性能电催化剂载体提供了重要的见解。
Three-dimensionally (3D) architectured carbon supports have received great attention for fuel cell catalysts. However, the complicated structure makes the assessment of catalytic properties difficult using the conventional rotating disk electrode (RDE) method. This paper reports a systematic study on oxygen reduction reaction (ORR) with ion-beam sputtered Pt catalyst (at Pt loadings of 6.5–43 μg cm− 2) on a vertically aligned carbon nanofiber (VACNF) array, consisting of conically stacked graphitic microstructures. The RDE studies reveal that thick 3D architecture of VACNFs exhibits enhanced limiting current density that deviates from the Levich equation for conventional thin-film catalysts. Nevertheless, useful information can be derived from RDE experiments with such systems. Molecular models representing VACNFs have been constructed to explore their capacity as catalyst supports for ORR. Platinum atoms form strong bonds at the open graphitic edges in VACNF, corroborating the role of VACNF in stabilizing Pt. Density Functional Theory (DFT) calculations further elucidate the two-electron and four-electron ORR pathways on the bare VACNF and Pt/VACNF catalysts, respectively. Furthermore, the Pt/VACNF catalysts show enhanced tolerance to methanol oxidation and a higher ability to recover from carbon monoxide poisoning in comparison to the benchmark Pt/C catalysts. These results provide critical insights for developing future high-performance electrocatalyst supports.