• Schuhmann, Wolfgang
• Chandra, Shubhadeep
• Junqueira, João R. C.
• Varhade, Swapnil
• Dieckhöfer, Stefan
• Gao, Huimin
• He, Wenhui
• Seisel, Sabine
• Quast, Thomas

Abstract

<jats:title>Abstract</jats:title><jats:p>Renewable electricity‐powered nitrate (NO<jats:sub>3</jats:sub><jats:sup>−</jats:sup>) reduction reaction (NO<jats:sub>3</jats:sub>RR) offers a net‐zero carbon route to the realization of high ammonia (NH<jats:sub>3</jats:sub>) productivity. However, this route suffers from low energy efficiency (EE, with a half‐cell EE commonly &lt;36%), since high overpotentials are required to overcome the weak NO<jats:sub>3</jats:sub><jats:sup>−</jats:sup> binding affinity and sluggish NO<jats:sub>3</jats:sub>RR 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 NO<jats:sub>3</jats:sub><jats:sup>−</jats:sup> adsorption and rapid tandem catalysis of NO<jats:sub>3</jats:sub><jats:sup>−</jats:sup> to NH<jats:sub>3</jats:sub>, 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 (NO<jats:sub>2</jats:sub>). As a result, a stable NO<jats:sub>3</jats:sub>RR with a current density of ≈450 mA cm<jats:sup>−2</jats:sup> is achieved, a Faradaic efficiency of &gt;97% for the formation of NH<jats:sub>3</jats:sub>, and an unprecedented half‐cell EE of ≈42%.</jats:p>

Topics

• density
• impedance spectroscopy
• polymer
• Carbon
• phase
• Nitrogen
• copper
• cobalt
• current density
• Raman spectroscopy