Electrocatalytic oxidation of alcohols using heterogeneous catalysts is a promising aqueous, energy-efficient, and environmentally friendly approach, especially for coupling different alcohols to prolong the carbon chain via co-oxidation. Precisely regulating critical steps to tailor electrode materials and electrolyte composition is key to selectively coupling alcohols for targeted synthesis. However, selective coupling different alcohols remains challenging due to the lack of effective catalyst and electrolyte design promoting specific pathways. Herein, we demonstrate a paired electrolysis strategy for combining anodic oxidative coupling of ethanol (EtOH) and benzyl alcohol (PhCH2OH) to synthesize cinnamaldehyde (CAL) and cathodic ammonia production. The strategies involve: (1) Utilizing the salt-out effect to balance selective oxidation and coupling rates; (2) Developing platinum-loaded nickel hydroxide electrocatalysts to accelerate intermediate coupling kinetics; (3) Introducing thermodynamically favorable nitrate reduction at the cathode to improve coupling selectivity by avoiding hydrogenation of products while generating valuable ammonia instead of hydrogen. 85% coupling selectivity and 278 μmol/h NH3 productive rate were achieved at 100 mA/cm2 with low energy input (∼1.63 V). The membrane-free, low energy, scalable approach with wide substrate scope highlights promising applications of this methodology. This work advances heterogeneous electrocatalytic synthesis through rational design principles that integrate anodic oxidative coupling with cathodic nitrate reduction reactions having synergistic effects on efficiency and selectivity.

中文翻译：

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将阳极醇氧化偶联形成 C-C 键与阴极氨生产相结合

使用非均相催化剂对醇进行电催化氧化是一种有前景的水相、节能且环保的方法，特别是通过共氧化偶联不同的醇以延长碳链。精确调节关键步骤以定制电极材料和电解质组成是选择性偶联醇进行目标合成的关键。然而，由于缺乏促进特定途径的有效催化剂和电解质设计，选择性偶联不同的醇仍然具有挑战性。在此，我们展示了一种配对电解策略，将乙醇（EtOH）和苯甲醇（PhCH2OH）的阳极氧化偶联结合起来合成肉桂醛（CAL）和阴极氨生产。其策略包括：（1）利用盐析效应来平衡选择性氧化和偶联速率； (2) 开发负载铂的氢氧化镍电催化剂以加速中间偶联动力学； (3)在阴极引入热力学上有利的硝酸盐还原，通过避免产物氢化同时产生有价值的氨而不是氢气来提高偶联选择性。在 100 mA/cm2 和低能量输入（~1.63 V）下实现了 85% 的耦合选择性和 278 μmol/h 的 NH3 产率。这种无膜、低能耗、可扩展的方法具有广泛的底物范围，凸显了该方法的有前景的应用。这项工作通过合理的设计原理推进了多相电催化合成，将阳极氧化偶联与阴极硝酸盐还原反应相结合，对效率和选择性具有协同作用。