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Electrochemical conversion of nitrate, a widespread water pollutant, into high-value-added ammonia is a renewable and delocalized route to restore the globally perturbed nitrogen cycle. However, premature desorption of catalytic intermediates and the competitive reaction of hydrogen evolution make the current performance still far from suitable for practical applications. In this work, a Zr-based metal−organic framework (MOF) is in situ constructed at the reaction interface to serve as a smart channel for the highly selective electrocatalytic reduction of nitrate to ammonia. The secondary coordination interaction introduced by the pendant Brønsted acidic groups of MOF not only effectively stabilize the catalytic intermediates to facilitate the overall reaction process but also certainly increase the proton activation barrier to suppress the competing hydrogen evolution reaction. When coupled with a nanocluster active center, the proof-of-concept system achieves simultaneous improvement in three critical parameters, with a nitrate conversion rate of 97.6%, an ammonia selectivity of 95.2%, and a Faradaic efficiency of 91.4% at −1.0 V (vs RHE) under ultralow nitrate concentration conditions. This strategy provides an interesting route for the application of MOFs and paves the way for the removal of nitrate and its reduction to ammonia.

The electrochemical nitrate reduction reaction (NO3RR) is a promising approach for nitrate removal and NH3 synthesis at ambient conditions. As a complex eight‐electron/nine‐proton transfer process, its performance relies heavily on the adsorption ability of reaction intermediates on the catalyst surface, which is determined by the geometric and electronic configurations of active sites. In this work, a heteroatom ensemble effect is deliberately triggered over RuFe bimetallic alloy to optimize intermediate adsorption for NO3RR. A record‐high NH3 yield rate of 118.8 mg h−1 mg−1 and a high Faradaic efficiency of 92.2% are achieved at −1.4 V vs reversible hydrogen electrode, ranking at the top of the state‐of‐the‐art. Experimental and computational results reveal that the geometric and electronic characteristics of the induced heteroatom ensemble effect play crucial roles. Both Ru and Fe display a continuous state throughout the Fermi level, suggesting high electron density benefits the whole NO3RR. As a result, facilitated adsorption of NO3−, efficient stabilization of key intermediates, as well as the timely desorption of NH3 are simultaneously achieved, thus significantly promoting the direct reduction of NO3− to NH3.

No abstract

Aqueous zinc-ion batteries have attracted extensive attention, but the formation of zinc dendrites has limited the commercialization of batteries. Furthermore, on account of tip effect, Zn cations tend to deposit...