Electrochemical nitrite (NO₂⁻) reduction offers a sustainable route for ammonia (NH₃) synthesis while simultaneously removing contaminants in wastewater. However, its efficiency is often limited by low catalytic efficiency and the competitive hydrogen evolution reaction at low NO₂⁻ concentrations. Herein, we report an intermittent pulsed electrolysis (IPE) strategy using copper oxide (Cu_xO) nanowires, which significantly enhances the NH₃ yield rate and Faradaic efficiency (FE) at lower reactant concentrations. In situ experiments and theoretical calculations reveal that alternating between open-circuit and cathodic potentials modulates the copper oxidation states, stabilizing the catalytically active cuprous oxide (Cu₂O). Consequently, the IPE approach provides an outstanding NH₃ yield rate of 115.10 mg·h⁻¹·cm⁻² and FE of 91.14% in the presence of 25 mM NO₂⁻, markedly outperforming conventional constant potential electrolysis.

Low-grade heat (< 100 °C) is abundant in the environment, which is the key to alleviating the potential energy crisis of modern society through reasonable heat energy conversion and storage. Most thermal regenerative electrochemical cycle systems (TREC) rely on external power for charging, resulting in additional energy loss. Here, we report a charging-free redox flow battery for continuous high-power, low-grade heat harvesting based on thermosensitive crystallization-boosted TREC. Using molecular dynamics (MD) and density functional theory (DFT), we analyzed the mesoscopic intermolecular interactions, radial distribution, and solvation structure variations of [Fe(CN)₆]³⁻/[Fe(CN)₆]⁴⁻ across varying temperatures. These insights elucidate the mechanism of thermosensitive crystallization evolution and its influence on entropy change during the thermodynamic cycle. By rationally adjusting redox activity at various temperatures, the system achieves an impressive temperature coefficient of −3.72 mV/K and a full-cell coefficient averaging –2.78 mV/K, exceeding the highest value of reported charging-free TRECs. The maximum power density also exceeds 3 times the best-reported charging-free TREC.

Electrocatalytic reduction of nitrate (NO₃⁻) and nitride (NO₂⁻) to ammonia (NH₃) is of wide interest as a promising alternative to the energy-intensive Haber-Bosch route for mitigating the vast energy consumption and the accompanied carbon dioxide emission, as well as benefiting for the relevant sewage treatment. However, exploring an efficient and low-cost catalyst with high atomic utilization that can effectively facilitate the slow multi-electron transfer process remains a grand challenge. Herein, we present an efficient hydrogenation of NO₃⁻/NO₂⁻ species to NH₃ in both alkaline and neutral environments over the Fe₂(MoO₄)₃ derived hybrid electrocatalyst with the metallic Fe site on FeMoO₄ (Fe/FeMoO₄). The Mo ingredient can play a synergistically positive role in further promoting the NH₃ production on Fe. As a result, Fe/FeMoO₄ behaves well in the electrochemical NH₃ generation from NO₂⁻ with a maximum NH₃ Faradaic efficiency (FE) of 96.53% and 87.68% in alkaline and neutral electrolyte, corresponding to the NH₃ yield rate of 640.68 and 302.56 mg·h⁻¹·mg_cat. ⁻¹, respectively, which outperforms the Fe and Mo counterpart and other similar catalyst, showing the robust catalytic capacity of each active site.

Efficient oxygen electrocatalysts are the key elements of numerous energy storage and conversion devices, including fuel cells and metal–air batteries. In order to realize their practical applications, highly efficient and inexpensive non-noble metal-based oxygen electrocatalysts are urgently required. Herein, we report a novel iron-chelated urea-formaldehyde resin hydrogel for the synthesis of Fe-N-C electrocatalysts. This novel hydrogel is prepared using a new instantaneous (20 s) one-step scalable strategy, which theoretically ensures the atomic-level dispersion of Fe ions in the urea-formaldehyde resin, guaranteeing the microstructural homogeneity of the electrocatalyst. Consequently, the prepared electrocatalyst exhibits higher catalytic activity and durability in the oxygen reduction (ORR) and evolution (OER) reactions than the commercial Pt/C catalyst. Furthermore, the above catalyst also shows a much better performance in rechargeable Zn–air batteries, including higher power density and better cycling stability. The developed synthetic approach opens up new avenues toward the development of sustainable active electrocatalysts for electrochemical energy devices.