H在SiC水中腐蚀中的意外作用
An Unexpected Role of H During SiC Corrosion in Water
摘要：
在水腐蚀过程中，固体中的原子与氧发生化学反应，导致氧化膜的形成或基质材料的溶解。通常，腐蚀的第一步涉及来自解离水的氧原子，其与表面原子反应并破坏近表面键。相反，表面上的氢通常用作钝化物质。在这里，我们发现，O和H的作用是颠倒的Si终止的SiC表面上的早期腐蚀阶段。O在表面上形成稳定的物种，并且通过破坏Si-C键的H发生化学侵蚀。这种所谓的氢断裂反应是通过新发现的亚稳态桥接羟基实现的，该羟基可以在水解离过程中形成。在水侵蚀期间从表面置换的Si原子随后形成H2SiO 3，其是形成二氧化硅和草酸的已知前体。这项研究表明，H和O在氧化中的作用需要重新考虑。
英文摘要：
During aqueous corrosion, atoms in the solid react chemically with oxygen, leading either to the formation of an oxide film or to the dissolution of the host material. Commonly, the first step in corrosion involves an oxygen atom from the dissociated water that reacts with the surface atoms and breaks near surface bonds. In contrast, hydrogen on the surface often functions as a passivating species. Here, we discovered that the roles of O and H are reversed in the early corrosion stages on a Si terminated SiC surface. O forms stable species on the surface, and chemical attack occurs by H that breaks the Si-C bonds. This so-called hydrogen scission reaction is enabled by a newly discovered metastable bridging hydroxyl group that can form during water dissociation. The Si atom that is displaced from the surface during water attack subsequently forms H2SiO3, which is a known precursor to the formation of silica and silicic acid. This study suggests that the roles of H and O in oxidation need to be reconsidered.
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