中心金属离子的缺失使酞菁在In$_2$O$_3$(111)上不稳定

中文摘要 AI 辅助

金属酞菁（MPc）是一种多功能分子平台，应用范围从有机光电器件到单原子催化（SAC）。它们在有机光电器件典型透明电极基底上的吸附和层形成，直接关系到有机-氧化物界面的电荷注入和传输。此外，金属阳离子明确的M-N$_4$配位决定了它们作为（电）催化SAC的活性。本文利用低温STM、nc-AFM和STS表征了无金属酞菁（H$_2$Pc）在In$_2$O$_3$(111)上的吸附。In$_2$O$_3$不仅是氧化铟锡（ITO）的模型体系，也是CO$_2$还原的活性催化材料。H$_2$Pc吸附的位点和构型与铜酞菁[J. Mater. Chem. C 13, 17650-17661 (2025)]及大多数钴酞菁[Surf. Sci. 722, 122065 (2022)]所报道的相同。尽管吸附位点偏好一致，但通过温和退火无法将H$_2$Pc组织成扩展的有序单层结构：分子在约50°C时开始分解，远低于生长CoPc和CuPc单层所用的温度。在化学计量比的In$_2$O$_3$(111)上未观察到自金属化。在存在In$^0$吸附原子的还原表面上，出现了新的H$_2$Pc相关特征，但仅通过成像无法识别。将H$_2$Pc与CoPc和CuPc进行比较，确定了中心金属离子在金属-Pc/In$_2$O$_3$(111)体系中的不同作用：它作为结构锚，稳定大环分子在表面上的稳定性，防止其分解；同时它改变前沿轨道特性，决定是否占据第二种吸附构型。

英文摘要

Metal phthalocyanines (MPc) are a versatile molecular platform for applications ranging from organic optoelectronic devices to single-atom catalysis (SAC). Their adsorption and layer formation on the prototypical transparent electrode substrates of organic optoelectronic devices is directly relevant for charge injection and transport across the organic-oxide interface. Moreover, the well-defined M-N$_4$ coordination of the metal cation defines their activity as SACs for (electro-)catalysis. Here, the adsorption of the metal-free phthalocyanine (H$_2$Pc) is characterized on In$_2$O$_3$(111) using low-temperature STM, nc-AFM, and STS. In$_2$O$_3$ is not only a model system of indium tin oxide (ITO) but also an active catalytic material for CO$_2$ reduction. H$_2$Pc adsorbs in the same site and configuration reported for copper phthalocyanine [J. Mater. Chem. C 13, 17650-17661 (2025)] and for the majority of cobalt phthalocyanine [Surf. Sci. 722, 122065 (2022)]. Despite this shared preference in adsorption site, H$_2$Pc cannot be organized into extended and ordered monolayer structures by gentle annealing: the molecule starts to decompose at $\approx$50$^\circ$C, well below the temperature used to grow monolayers of CoPc and CuPc. Self-metalation is not observed on stoichiometric In$_2$O$_3$(111). On the reduced surface where In$^0$ adatoms are present, new H$_2$Pc-related features appear but cannot be identified by imaging only. The comparison of H$_2$Pc with CoPc and CuPc identifies distinct roles of the central metal ion in the metal-Pc/In$_2$O$_3$(111) systems: it acts as a structural anchor that stabilizes the macrocycle against decomposition on the surface, and it modifies the frontier-orbital character in ways that determine whether a second adsorption configuration is populated.

发表机构

• Institute of Applied Physics, TU Wien（维也纳工业大学应用物理研究所）

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