The electrocatalytic activity of MnO materials derived from the metal-organic framework (Mn-BTC) was investigated in dry (for lithium-ion batteries (LIBs)) and wet (for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER)) conditions while observing the phase transformation from annealing Mn-BTC in the air. As a result, the partial α-MnO, MnO, and MnO phases were formed at 300, 500, and 700 °C, respectively. The electrocatalytic activity of MnO materials follows the order (MnO > MnO > α-MnO > Mn-BTC) in both dry and wet conditions. For instance, MnO electrodes delivered an initial discharge/charge capacity of 1302/815 mAh g with an initial Coulombic efficiency of 62.6% when used as anodes for LIBs. They also exhibited a lower Tafel slope of 116 and 54 mV dec when applied to HER and OER, respectively. The structural analysis showed that the best electrocatalytic activity of MnO samples originated from the spinel MnO structure with Mn/Mn ions occupying the tetrahedral and octahedral sites, high electrical conductivity and small grain size. This study provides insights into the role of physicochemical properties in controlling MnO phases from Mn-BTC materials via the annealing process towards applications as potential electrode materials for LIBs, HER, and OER.

中文翻译：

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MnxOy衍生金属有机骨架对锂离子电池的电催化活性、析氢反应和析氧反应

研究了源自金属有机骨架 (Mn-BTC) 的 MnO 材料在干态（用于锂离子电池 (LIB)）和湿态（用于析氢反应 (HER) 和析氧反应 (OER)）的电催化活性条件，同时观察 Mn-BTC 在空气中退火的相变。结果，部分α-MnO、MnO和MnO相分别在300、500和700℃下形成。在干燥和潮湿条件下，MnO材料的电催化活性均遵循（MnO > MnO > α-MnO > Mn-BTC）的顺序。例如，MnO电极用作LIB阳极时，初始放电/充电容量为1302/815 mAh g，初始库仑效率为62.6%。当应用于 HER 和 OER 时，它们还分别表现出较低的塔菲尔斜率，分别为 116 和 54 mV dec。结构分析表明，MnO样品的最佳电催化活性来源于尖晶石MnO结构，Mn/Mn离子占据四面体和八面体位点，电导率高，晶粒尺寸小。这项研究深入探讨了物理化学性质在通过退火过程控制 Mn-BTC 材料中的 MnO 相以作为 LIB、HER 和 OER 潜在电极材料的应用方面的作用。