Redox Properties of Iron Sulfides: Direct versus Catalytic Reduction and Implications for Catalyst Design
Redox Properties of Iron Sulfides: Direct versus Catalytic Reduction and Implications for Catalyst Design
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DOI：
10.1002/cctc.202200270
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发表时间：
2022-04-27
期刊：
影响因子：
4.5
通讯作者：
Hocking, Rosalie K.
中科院分区：
文献类型：
--
作者：
Garibello, C. Felipe;Simonov, Alexandr N.;Hocking, Rosalie K.
在电催化中，我们很少考虑可能与催化介导的还原同时发生的竞争性直接还原反应-直接氧化还原化学反应通常发生得较慢，但与催化反应竞争。从这个角度来看，感兴趣的一类化合物是硫化铁。除了在结构上与许多金属蛋白相似外，硫化铁也是自然界最强的化学还原剂之一，据报道可作为关键化学反应的催化剂，包括质子，亚硝酸盐和硝酸盐还原。重要的是，硫化铁可以作为催化剂，因为它们也是足够强的还原剂，可以直接介导一些相同的反应。这是矛盾的，因为为了成为还原的催化剂，硫化铁也不能被氧化。为了进一步研究这一现象，我们组装了一个测试集的硫化铁跨越无定形硫化铁（FeSam）以及结晶硫化铁云铁矿，黄铁矿和硫铁矿。以NO_2 ~-为实验底物，探讨了直接还原与二次电子源催化还原反应的关系。直接还原的趋势从最不稳定的材料（FeSam）到最稳定的材料（FeS 2）。在所研究的相中，硫铁矿（FeS）显示出直接还原和催化还原之间的最大差异，然而无定形硫化铁显示出作为直接还原剂和催化剂的NH3/NH 4+生产的最大选择性。
In electrocatalysis we seldom think about the competing direct reduction reactions that may happen alongside catalytically mediated reduction- with direct redox chemistry often happening slower but in competition with, catalysis. One class of compounds of interest from this perspective are iron sulfides. In addition to being structurally similar to many metalloproteins, iron sulfides are also among nature's strongest chemical reductants and reported to act as catalysts for key chemical reactions including proton, nitrite, and nitrate reduction. It is important that iron sulfides can act as catalysts because they are also strong enough reductants to mediate some of the same reactions directly. This is paradoxical because in order to be a catalyst for reduction, an iron sulfide cannot also be oxidised. To investigate this phenomenon further, we assembled a test set of iron sulfides spanning both amorphous iron sulfide (FeSam) as well as the crystalline iron sulfides greigite, pyrite, and troilite. These were used to explore the relationship between direct reduction and catalysis of a reduction reaction with a secondary electron source, NO2- was chosen as a test substrate. The trends in direct reduction followed the least stable material (FeSam) to the most stable material (FeS2). Of the phases studied, troilite (FeS) showed the largest difference between direct and catalytic reduction, however amorphous iron sulfide showed the greatest selectivity for NH3/NH4+ production as both a direct reductant and a catalyst.