Wagner Stephan, Auerbach Hendrik, Tait Claudia E, Martinaiou Ioanna, Kumar Shyam C N, Kübel Christian, Sergeev Ilya, Wille Hans-Christian, Behrends Jan, Wolny Juliusz A, Schünemann Volker, Kramm Ulrike I
TU Darmstadt, Graduate School Energy Science and Engineering, Otto-Berndt-Str. 3, 64287, Darmstadt, Germany.
TU Darmstadt, Department of Material and Earth Sciences, Otto-Berndt-Str. 3, 64287, Darmstadt, Germany.
Angew Chem Int Ed Engl. 2019 Jul 29;58(31):10486-10492. doi: 10.1002/anie.201903753. Epub 2019 Jul 1.
Fe-N-C catalysts are very promising materials for fuel cells and metal-air batteries. This work gives fundamental insights into the structural composition of an Fe-N-C catalyst and highlights the importance of an in-depth characterization. By nuclear- and electron-resonance techniques, we are able to show that even after mild pyrolysis and acid leaching, the catalyst contains considerable fractions of α-iron and, surprisingly, iron oxide. Our work makes it questionable to what extent FeN sites can be present in Fe-N-C catalysts prepared by pyrolysis at 900 °C and above. The simulation of the iron partial density of phonon states enables the identification of three FeN species in our catalyst, one of them comprising a sixfold coordination with end-on bonded oxygen as one of the axial ligands.
铁氮碳催化剂是用于燃料电池和金属空气电池的非常有前景的材料。这项工作对铁氮碳催化剂的结构组成提供了基本见解，并突出了深入表征的重要性。通过核共振和电子共振技术，我们能够表明，即使经过温和的热解和酸浸，该催化剂仍含有相当比例的α-铁，而且令人惊讶的是还含有氧化铁。我们的工作使人们对在900°C及以上温度热解制备的铁氮碳催化剂中能在多大程度上存在FeN位点产生了疑问。对声子态铁部分密度的模拟能够识别出我们催化剂中的三种FeN物种，其中一种包含与作为轴向配体之一的端基键合氧的六重配位。
