The electrocatalytic reduction of nitrate (ERN) to ammonia offers a promising route to address energy shortages and environmental pollution, but its practical application is hindered by low selectivity due to complex eight-electron transfer pathways and high energy consumption (EC) from the kinetically sluggish oxygen evolution reaction (OER). This study proposes a dual strategy: (1) designing a multi-functional self-supported ANP electrode via vapor deposition to enhance ERN activity and (2) replacing the OER with thermodynamically favorable anodic reactions (urea oxidation reaction (UOR), sodium metabisulfite oxidation reaction (S(IV)OR), sulfite and urea oxidation reaction (S(IV)/UOR)) to reduce EC. The ANP cathode achieved a nitrate removal rate (R%) of 97.7%, ammonia selectivity (SE%) of 91.8%, and Faradaic efficiency (FE) of 97.3% at −1.2 V, with an ammonia yield of 0.0616 mmol h⁻¹ mg⁻¹ and an EC of 8.239 kWh/kg, while in situ-generated atomic hydrogen (*H) was identified as key to improving nitrate removal and selectivity. Replacing the OER with alternative anodic reactions significantly improved system efficiency: the UOR reduced EC by 17.5%, S(IV)OR saved 27.6% energy with 7.1% higher ammonia yield, and a hybrid S(IV)/UOR system achieved a 32.1% lower EC and a 12.6% greater ammonia yield than the OER. These differences stemmed from variations in cell voltage and ammonia production rates. This work provides a viable approach for selective nitrate-to-ammonia conversion and guides the design of energy-efficient electrocatalytic systems for sustainable nitrogen recovery.

Carbon dioxide (CO₂) capture is a cornerstone of global carbon neutrality, yet the high energy penalty associated with solvent regeneration—particularly for monoethanolamine (MEA) systems—remains a major barrier to its sustainable deployment. This study presents a sustainable and high-performance catalytic solution using micro-sized iron oxyhydroxide (β-FeOOH). Characterized by a high specific surface area ($287 m²/g) and a synergistic distribution of abundant Lewis and Brønsted acid sites, the β-FeOOH catalyst significantly enhances CO₂ desorption kinetics. Experimental results demonstrate that the incorporation of β-FeOOH into a 30 wt% MEA solution increases the CO₂ desorption rate by 10.9% while simultaneously lowering the regeneration temperature from the conventional 120 °C to 85 °C. Such a reduction in thermal requirements offers a pathway to utilize low-grade industrial waste heat, drastically improving the process’s energy efficiency. Furthermore, the catalyst exhibited remarkable cyclic stability over ten consecutive cycles, maintaining its structural integrity and catalytic activity. These findings highlight β-FeOOH as an eco-friendly, cost-effective, and robust catalyst that aligns with the principles of green chemical engineering, offering a scalable strategy to enhance the sustainability of carbon capture operations.