Accelerating Nitrate Electroreduction to Ammonia via Metal-Support Interactions in Ni-WS₂ Catalysts

Electrocatalytic nitrate reduction reaction (NO₃^-RR) is a promising route for both treating NO₃^--containing wastewater and enabling sustainable ammonia (NH₃) synthesis. While two-dimensional (2D) transition metal dichalcogenides (TMDs) catalysts have been widely investigated as catalysts in various electrocatalytic reactions, their practical application in NO₃^-RR remains hindered by inherently sluggish kinetics and insufficient stability. Metal-support interaction (MSI), which enhances charge transfer and stabilizes catalytic sites, offers a compelling strategy to address these challenges. Herein, we design an MSI-driven Ni-WS₂ catalyst via a two-step strategy. The Ni-WS₂ catalyst demonstrates outstanding NO₃^-RR performance, achieving a Faradaic efficiency of 91.7% at -0.3 V_RHE with an NH₃ yield rate of 23.3 mg h^-1 cm^-2 at -0.7 V_RHE. Significantly, the Ni-WS₂ catalyst maintained an exceptional stability in a membrane electrode assembly (MEA), sustaining ≈32 mg h^-1 cm^-2 NH₃ production over 100 h, surpassing most previously reported TMD-based catalysts. Density functional theory (DFT) calculations reveal that MSI between Ni metal and WS₂ support induces interfacial charge redistribution, optimizes adsorption energy of key intermediates and lowers the energy barrier for the rate-determining step (*NH₂ → *NH₃). Furthermore, the Zn-NO₃^- battery assembled with Ni-WS₂ cathode exhibits remarkable performance. This work advances a two-step synthesis strategy for high-performance NO₃^-RR electrocatalysts through targeted MSI modulation.