Decoupling Electron‐ and Phase‐Transfer Processes to Enhance Electrochemical Nitrate‐to‐Ammonia Conversion by Blending Hydrophobic PTFE Nanoparticles within the Electrocatalyst Layer
Decoupling Electron‐ and Phase‐Transfer Processes to Enhance Electrochemical Nitrate‐to‐Ammonia Conversion by Blending Hydrophobic PTFE Nanoparticles within the Electrocatalyst Layer
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DOI：
10.1002/aenm.202203891
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发表时间：
2023-01
影响因子：
27.8
通讯作者：
Jianan Gao;Qingquan Ma;Joshua Young;J. Crittenden;Wen Zhang
中科院分区：
文献类型：
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作者：
Jianan Gao;Qingquan Ma;Joshua Young;J. Crittenden;Wen Zhang
在环境条件下将硝酸盐电化学上循环为氨提供了一种可持续的合成途径，可以补充目前哈伯-博世工艺的工业NH3生产。关键的限速步骤之一是从电极表面有效地解吸气态或界面气泡产物，主要是NH3，以及一些少量的氮气和氢气的副产物，以保持NO3−还原反应的有效位置。为了促进气体产物从催化部位脱附，疏水的聚四氟乙烯(PTFE)纳米颗粒被混合在CuO催化层中，这被证明消除了电极表面的不期望的积累和堵塞，并在很大程度上解耦了电子和相转移过程。以电化学活性表面积(ECSA)归一化的NH_3部分电流密度从11.4±0.1mA·cm·−~2ECSA增加到203.3±1.8 mA·cm~2 ECSA，增加了近17.8倍。DFT和从头算分子动力学模拟表明，疏水的聚四氟乙烯纳米粒子可以作为隔离岛，增强溢出效应，并将气体产物从电催化剂输送到聚四氟乙烯中。因此，混合的PTFE/CuO电催化剂具有较高的氨转移效率。这一新的、简单的策略有望对未来的电化学放气电极设计起到启发作用。
Electrochemical upcycling of nitrate into ammonia at ambient conditions offers a sustainable synthesis pathway that can complement the current industrial NH3 production from the Haber–Bosch process. One of the key rate‐limiting steps is the effective desorption of gaseous or interfacial bubble products, mainly NH3 with some minor side products of nitrogen and hydrogen, from the electrode surfaces to sustain available sites for the NO3− reduction reaction. To facilitate the gaseous product desorption from the catalytic sites, hydrophobic polytetrafluoroethylene (PTFE) nanoparticles are blended within a CuO catalyst layer, which is shown to eliminate the undesirable accumulation and blockage of electrode surfaces and largely decouples the electron‐ and phase‐transfer processes. The NH3 partial current density normalized by the electrochemically active surface area (ECSA) increases by nearly a factor of 17.8 from 11.4 ± 0.1 to 203.3 ± 1.8 mA cm−2ECSA. The DFT and ab‐initio molecular dynamics simulations suggest that the hydrophobic PTFE nanoparticles may serve as segregated islands to enhance the spillover and transport the gaseous products from electrocatalysts to the PTFE. Thus, a higher ammonia transfer is achieved for the mixed PTFE/CuO electrocatalyst. This new and simple strategy is expected to act as inspiration for future electrochemical gas‐evolving electrode design.