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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...

Conversion of solar energy into thermal energy stored in phase change materials (PCMs) can effectively relieve the energy dilemma and improve energy utilization efficiency. However, facile fabrication of form-stable PCMs (FSPCMs) to achieve simultaneously energetic solar–thermal, conversion and storage remains a formidable challenge. Herein, we report a desirable solar–thermal energy conversion and storage system that utilizes paraffin (PW) as energy-storage units, the silver/polypyrrole-functionalized polyurethane (PU) foam as the cage and energy conversion platform to restrain the fluidity of the melting paraffin and achieve high solar–thermal energy conversion efficiency (93.7%) simultaneously. The obtained FSPCMs possess high thermal energy storage density (187.4 J/g) and an excellent leak-proof property. In addition, 200 accelerated solar–thermal energy conversion-cycling tests demonstrated that the resultant FSPCMs had excellent cycling durability and reversible solar–thermal energy conversion ability, which offered a potential possibility in the field of solar energy utilization technology.

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As the core of low‐temperature direct ammonia fuel cell (DAFC) technology, electrocatalytic ammonia oxidation reaction (AOR) has proven to be most active on platinum‐based catalysts. However, the AOR is extremely surface sensitive that only the Pt (200) facet exhibits high reaction activity, whereas other facets usually do not make contributions. Herein, the inert (220) surface of PtMo nano‐alloy is successfully awakened as one more active facet in addition to (200) via directional single‐atom Ni‐doping. The introduction of Ni triggers a targeted electron accumulation around Pt sites at the (220) facet that significantly reduces the AOR energy barrier while maintaining the activity of the (200) surface. With a greatly enlarged active surface, the Ni‐decorated PtMo catalyst exhibits a significantly facilitated AOR kinetics with a low onset potential of 0.49 V versus reversible hydrogen electrode and a superior peak current density of 94.96 A g−1 at 5 mV s−1. Notably, the DAFC equipped with such an electrocatalyst reaches a remarkable peak power density of 16.70 mW cm−2 at low temperatures. It is believed that this strategy sheds light on exploiting the intrinsic activity of Pt‐based electrocatalysts, and drives the low‐temperature DAFC technology to a more practical level.