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Enhanced Nitrate-to-Ammonia Efficiency over Linear Assemblies of Copper-Cobalt Nanophases Stabilized by Redox Polymers
Advanced Materials ( IF 29.4 ) Pub Date : 2023-05-26 , DOI: 10.1002/adma.202303050
Wenhui He 1 , Shubhadeep Chandra 1 , Thomas Quast 1 , Swapnil Varhade 1 , Stefan Dieckhöfer 1 , João R C Junqueira 1 , Huimin Gao 2 , Sabine Seisel 1 , Wolfgang Schuhmann 1
Affiliation  

Renewable electricity-powered nitrate (NO3) reduction reaction (NO3RR) offers a net-zero carbon route to the realization of high ammonia (NH3) productivity. However, this route suffers from low energy efficiency (EE, with a half-cell EE commonly <36%), since high overpotentials are required to overcome the weak NO3 binding affinity and sluggish NO3RR kinetics. To alleviate this, a rational catalyst design strategy that involves the linear assembly of sub-5 nm Cu/Co nanophases into sub-20 nm thick nanoribbons is suggested. The theoretical and experimental studies show that the Cu-Co nanoribbons, similar to enzymes, enable strong NO3 adsorption and rapid tandem catalysis of NO3 to NH3, owing to their richly exposed binary phase boundaries and adjacent Cu-Co sites at sub-5 nm distance. In situ Raman spectroscopy further reveals that at low applied overpotentials, the Cu/Co nanophases are rapidly activated and subsequently stabilized by a specifically designed redox polymer that in situ scavenges intermediately formed highly oxidative nitrogen dioxide (NO2). As a result, a stable NO3RR with a current density of ≈450 mA cm−2 is achieved, a Faradaic efficiency of >97% for the formation of NH3, and an unprecedented half-cell EE of ≈42%.

中文翻译:

氧化还原聚合物稳定的铜钴纳米相线性组件提高了硝酸盐转化为氨的效率

可再生电力驱动的硝酸盐(NO 3 )还原反应(NO 3 RR)为实现高氨(NH 3)生产率提供了一条净零碳途径。然而,该路线的能量效率较低(EE,半电池EE通常<36%),因为需要高过电势来克服弱的NO 3 - 结合亲和力和缓慢的NO 3 RR动力学。为了缓解这一问题,提出了一种合理的催化剂设计策略,该策略涉及将亚 5 nm Cu/Co 纳米相线性组装成亚 20 nm 厚的纳米带。理论和实验研究表明,Cu-Co纳米带与酶类似,由于其丰富的暴露二元相边界和相邻的Cu-Co位点,能够实现强NO 3 -吸附和NO 3 -到NH 3的快速串联催化。低于 5 nm 的距离。原位拉曼光谱进一步揭示,在低施加过电势下,Cu/Co纳米相被快速激活,随​​后通过专门设计的氧化还原聚合物稳定,该氧化还原聚合物原位清除中间形成的高度氧化性二氧化氮(NO 2 。结果,实现了电流密度为约450 mA cm -2的稳定NO 3 RR ,形成NH 3的法拉第效率>97% ,以及前所未有的约42%的半电池EE。
更新日期:2023-05-26
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