Catalytic Reduction of 4-Nitrophenol by Gold Catalysts: The Influence of Borohydride Concentration on the Induction Time
Catalytic Reduction of 4-Nitrophenol by Gold Catalysts: The Influence of Borohydride Concentration on the Induction Time
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DOI：
10.1021/acs.jpcc.9b02396
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发表时间：
2019-05-23
影响因子：
3.7
通讯作者：
Neretina, Svetlana
中科院分区：
文献类型：
--
作者：
Neal, Robert D.;Inoue, Yuko;Neretina, Svetlana
一个全面的机理框架是有效利用模型催化反应的关键。虽然硼氢化物还原4-硝基苯酚已成为评估纳米结构催化活性的最广泛使用的模型反应之一，但仍然存在知识空白。诱导时间是反应开始时似乎没有反应发生的一段时间，其原因长期以来一直是争论的主题。最近的工作提供了令人信服的实验证据，将诱导时间与含水反应物中溶解氧的消耗联系起来，并基于以前未知的副反应提供了一种机理性的理解。然而，有人提出了一个问题，即拟议的机制是无法解释先前的工作显示的诱导时间是独立的硼氢化物浓度。在这里，提出了一个系统的研究，重新审视这种依赖性，同时使用光谱和原位溶解氧探头监测反应。这种依赖性比以前的研究表明的要复杂得多，因为它随催化剂的添加量而变化。所达成的谅解与先前提出的上岗时间机制一致，并解决了与先前工作的不一致之处。
A comprehensive mechanistic framework is key to the effective utilization of model catalytic reactions. Although the reduction of 4-nitrophenol by borohydride has emerged as one of the most widely used model reactions for accessing the catalytic activity of nanostructures, there still exist knowledge gaps. The cause of the induction time, which is a period at the beginning of the reaction where no reaction seemingly occurs, has long been the subject of debate. Recent work provides compelling experimental evidence that links the induction time to the consumption of dissolved oxygen within the aqueous reactants and provides a mechanistic understanding based on a previously unknown side reaction. A concern has, however, been raised that the proposed mechanism is unable to account for prior work showing the induction time to be independent of the borohydride concentration. Here, a systematic study is presented that re-examines this dependency where reactions are simultaneously monitored using spectroscopy and an in situ dissolved oxygen probe. The dependency is shown to be far more involved than prior studies suggest because it varies with the amount of catalyst added. The understanding obtained is consistent with the previously proposed mechanism for the induction time and resolves perceived inconsistencies with earlier work.