Efficient Ammonia Electrosynthesis from Nitrate on Strained Ruthenium Nanoclusters

Abstract

The limitations of the Haber–Bosch reaction, particularly high-temperature operation, have ignited new interests in low-temperature ammonia-synthesis scenarios. Ambient N2 electroreduction is a compelling alternative but is impeded by a low ammonia production rate (mostly <10 mmol gcat –1 h–1), a small partial current density (<1 mA cm–2), and a high-selectivity hydrogen-evolving side reaction. Herein, we report that room-temperature nitrate electroreduction catalyzed by strained ruthenium nanoclusters generates ammonia at a higher rate (5.56 mol gcat –1 h–1) than the Haber–Bosch process. The primary contributor to such performance is hydrogen radicals, which are generated by suppressing hydrogen–hydrogen dimerization during water splitting enabled by the tensile lattice strains. The radicals expedite nitrate-to-ammonia conversion by hydrogenating intermediates of the rate-limiting steps at lower kinetic barriers. The strained nanostructures can maintain nearly 100% ammonia-evolving selectivity at >120 mA cm–2 current densities for 100 h due to the robust subsurface Ru–O coordination. These findings highlight the potential of nitrate electroreduction in real-world, low-temperature ammonia synthesis.

Single‐Atom Cu Catalysts for Enhanced Electrocatalytic Nitrate Reduction with Significant Alleviation of Nitrite Production

“…From the perspective of environmental scientists, the most desirable solution for nitrate removal is to selectively reduce it to harmless gaseous nitrogen, but few non‐noble metal catalysts available today can convert nitrate into nitrogen with a high selectivity. In this regard, recent studies [ 13–16 ] by chemical scientists have attempted to promote the selectively electrocatalytic reduction of nitrate to ammonia, a value‐added product utilized as a precursor to fertilizer.…”

Confining Chainmail‐Bearing Ni Nanoparticles in N‐doped Carbon Nanotubes for Robust and Efficient Electroreduction of CO2

“…They generally show enhanced activities, but the selectivities towards CO 2 RR are still poor [16–21] . To improve the catalyst selectivity, several strategies have been put forward to suppress HER in aqueous solutions, to name a few, hydrophobic layer incorporating, [22–24] strain engineering, [25] alloying, [26] hydrogen bonding [27] and hydrogen adsorption site blocking [28] . Recently, a confinement effect induced by pores, cavities or pits has turned out to be effective in suppressing HER in various electrochemical reactions [12,29–32] .…”

High-Throughput Screening Single-Atom Alloy for Electroreduction of Dinitrogen to Ammonia

“…Because of the inertness to HER and high stability, several noble metals have been reported as promising electrocatalysts, such as Au, Pt, and Ru. [7][8][9][10] Among them, Au exhibits the most efficient performance owing to the low activity of competitive HER. 11,12 Previous studies demonstrated that the lack of empty d-orbits to accept lone-pair electrons from N2 may result in extremely weak adsorption to N2, and herein difficulty in breaking triple N-N bond.…”