Atomically dispersed manganese catalysts for oxygen reduction in proton-exchange membrane fuel cells
Atomically dispersed manganese catalysts for oxygen reduction in proton-exchange membrane fuel cells
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DOI：
10.1038/s41929-018-0164-8
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发表时间：
2018-12-01
期刊：
影响因子：
37.8
通讯作者：
Wu, Gang
中科院分区：
文献类型：
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作者：
Li, Jiazhan;Chen, Mengjie;Wu, Gang
对于质子交换膜燃料电池中的氧还原反应(ORR)，不含铂族金属(PGM)的催化剂也是非常理想的，因为它们避免了可能的Fenton反应。在这里，我们报道了一种高效的ORR催化剂，它由原子分散的氮配位的单锰位在部分石墨炭(Mn-N-C)上组成。用X射线吸收光谱证实了原子分散的MnN4部分嵌入在碳表面暴露的基面内，并用具有原子分辨率的像差校正电子显微镜证实了它们的分散。与可逆氢电极相比，Mn-N-C催化剂的半波电位为0.80V，接近Fe-N-C催化剂的半波电位，在酸性介质中的稳定性显著提高。在燃料电池测试中，作为无PGM阴极的Mn-N-C催化剂表现出了令人鼓舞的性能。第一性原理计算进一步支持MNN4位是ORR活性的来源，在酸性介质中通过4E(-)途径。
Platinum group metal (PGM)-free catalysts that are also iron free are highly desirable for the oxygen reduction reaction (ORR) in proton-exchange membrane fuel cells, as they avoid possible Fenton reactions. Here we report an efficient ORR catalyst that consists of atomically dispersed nitrogen-coordinated single Mn sites on partially graphitic carbon (Mn-N-C). Evidence for the embedding of the atomically dispersed MnN4 moieties within the carbon surface-exposed basal planes was established by X-ray absorption spectroscopy and their dispersion was confirmed by aberration-corrected electron microscopy with atomic resolution. The Mn-N-C catalyst exhibited a half-wave potential of 0.80 V versus the reversible hydrogen electrode, approaching that of Fe-N-C catalysts, along with significantly enhanced stability in acidic media. The encouraging performance of the Mn-N-C catalyst as a PGM-free cathode was demonstrated in fuel cell tests. First-principles calculations further support the MnN4 sites as the origin of the ORR activity via a 4e(-) pathway in acidic media.