Catalytic methanolysis of ammonia borane (NH₃BH₃) is a prospective technology in the field of hydrogen energy in which hydrogen production and hydrogen storage can be integrated together. The splitting of the O–H bond is identified as the rate-determining step (RDS) in this reaction. Thus, a deep understanding of the relationship between the electronic structure of the catalyst, especially the localized electron density of active sites, and the breaking behaviors of the O–H bond is of extreme importance for the rational design of robust catalysts for the reaction. In this work, sea urchin-like tricobalt tetroxide/copper oxide (Co₃O₄/CuO) nanostructures with rich oxygen vacancies (O_v) were fabricated by a simple synthetic route. In NH₃BH₃ methanolysis, the optimal Co₃O₄/CuO sample exhibited ultrahigh catalytic activity with a turnover frequency (TOF) of 87.5 min^–1. Interestingly, when NH₃BH₃ methanolysis was carried out under visible-light illumination, the TOF further increased to 116.4 min^–1, which is the highest TOF value among those of the noble-metal-free catalysts ever documented in the literature. Theoretical calculation results evidenced that the Cu site in the Co₃O₄/CuO sample was in charge of the adsorption and activation of methanol molecules. Both the O_v and visible-light illumination can help electrons on the Cu site flow to the adsorbed methanol molecule, thus leading to localized electron redistribution of the methanol molecule and the extension of the O–H bond. The cooperation of O_v and visible light makes splitting of the O–H bond easier, which is favorable for fast hydrogen release from NH₃BH₃ methanolysis. This study helps us to gain an insight into the influence of localized electron redistribution of methanol molecules on the RDS, which conduces to the rational design of highly effective nanocatalysts. Moreover, the coinduction strategy for localized electron redistribution with oxygen vacancy engineering and visible-light illumination opens up a route to boost catalytic activity in NH₃BH₃ methanolysis.

中文翻译：

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海上甲醇分子中的局部电子再分布 用于快速氢释放的海胆样四氧化三钴/氧化铜纳米结构


氨硼烷催化甲烷分解 （NH₃BH₃） 是氢能领域的一种前瞻性技术，其中制氢和储氢可以集成在一起。O-H 键的分裂被确定为该反应中的速率决定步骤 （RDS）。因此，深入了解催化剂的电子结构，尤其是活性位点的局部电子密度与 O-H 键的断裂行为之间的关系，对于合理设计用于反应的稳健催化剂极为重要。在这项工作中，通过简单的合成路线制备了具有丰富氧空位 （O_v） 的海胆样四氧化三氢盐/氧化铜 （Co₃O₄/CuO） 纳米结构。在 NH₃BH₃ 甲烷分解中，最佳 Co₃O₄/CuO 样品表现出超高催化活性，周转频率 （TOF） 为 87.5 min^–1。有趣的是，当在可见光照射下进行 NH₃BH₃ 甲烷分解时，TOF 进一步增加到 116.4 min^–1，这是文献中记录的无贵金属催化剂中最高的 TOF 值。理论计算结果证明，Co₃O₄/CuO 样品中的 Cu 位点负责甲醇分子的吸附和活化。O_v 和可见光照明都可以帮助 Cu 位点上的电子流向吸附的甲醇分子，从而导致甲醇分子的局部电子重新分布和 O-H 键的延伸。 O_v 和可见光的配合使 O-H 键更容易分裂，这有利于从 NH₃BH₃ 甲烷分解中快速释放氢气。这项研究有助于我们深入了解甲醇分子的局部电子重分布对 RDS 的影响，这有助于合理设计高效纳米催化剂。此外，具有氧空位工程和可见光照明的局部电子再分布的共诱导策略为提高 NH₃BH₃ 甲烷分解的催化活性开辟了一条途径。