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Energy‐Efficient Nitrogen Reduction to Ammonia at Low Overpotential in Aqueous Electrolyte under Ambient Conditions
Author(s) -
Wang Dabin,
Azofra Luis Miguel,
Harb Moussab,
Cavallo Luigi,
Zhang Xinyi,
Suryanto Bryan H. R.,
MacFarlane Douglas R.
Publication year - 2018
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201801632
Subject(s) - overpotential , chemistry , faraday efficiency , redox , reversible hydrogen electrode , ammonia production , aqueous solution , electrochemistry , catalysis , selectivity , inorganic chemistry , ammonia , electrolyte , yield (engineering) , electrode , materials science , working electrode , organic chemistry , metallurgy
The electrochemical nitrogen reduction reaction (NRR) under ambient conditions is a promising alternative to the traditional energy‐intensive Haber–Bosch process to produce NH 3 . The challenge is to achieve a sufficient energy efficiency, yield rate, and selectivity to make the process practical. Here, we demonstrate that Ru nanoparticles (NPs) enable NRR in 0.01 m HCl aqueous solution at very high energy efficiency, that is, very low overpotentials. Remarkably, the NRR occurs at a potential close to or even above the H + /H 2 reversible potential, significantly enhancing the NRR selectivity versus the production of H 2 . NH 3 yield rates as high as ≈5.5 mg h −1 m −2 at 20 °C and 21.4 mg h −1 m −2 at 60 °C were achieved at a redox potential ( E ) of − 100 mV versus the reversible hydrogen electrode (RHE), whereas a highest Faradaic efficiency (FE) of ≈5.4 % is achievable at E=+ 10 mV vs. RHE. This work demonstrates the potential use of Ru NPs as an efficient catalyst for NRR at ambient conditions. This ability to catalyze NRR at potentials near or above RHE is imperative in improving the NRR selectivity towards a practical process as well as rendering the H 2 viable as byproduct. Density functional theory calculations of the mechanism suggest that the efficient NRR process occurring on these predominantly Ru (0 0 1) surfaces is catalyzed by a dissociative mechanism.