Li Nancy, Hadt Ryan G, Hayes Dugan, Chen Lin X, Nocera Daniel G
Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA.
Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, IL, USA.
Nat Commun. 2021 Jul 9;12(1):4218. doi: 10.1038/s41467-021-24453-6.
Iron alloying of oxidic cobaltate catalysts results in catalytic activity for oxygen evolution on par with Ni-Fe oxides in base but at much higher alloying compositions. Zero-field Fe Mössbauer spectroscopy and X-ray absorption spectroscopy (XAS) are able to clearly identify Fe in mixed-metal Co-Fe oxides. The highest Fe population is obtained in the 40-60% Fe alloying range, and XAS identifies the ion residing in an octahedral oxide ligand field. The oxygen evolution reaction (OER) activity, as reflected in Tafel analysis of CoFeO films in 1 M KOH, tracks the absolute concentration of Fe. The results reported herein suggest an important role for the formation of the Fe redox state in activating cobaltate OER catalysts at high iron loadings.
氧化钴酸盐催化剂的铁合金化产生的析氧催化活性与碱性条件下的镍铁氧化物相当，但合金化组成要高得多。零场铁穆斯堡尔光谱和X射线吸收光谱（XAS）能够清楚地识别混合金属钴铁氧化物中的铁。在40-60%的铁合金化范围内获得了最高的铁含量，并且XAS确定离子存在于八面体氧化物配体场中。1M KOH中CoFeO薄膜的塔菲尔分析所反映的析氧反应（OER）活性与铁的绝对浓度相关。本文报道的结果表明，在高铁负载量下，铁氧化还原态的形成在激活钴酸盐OER催化剂方面起着重要作用。
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