NiFeCoRuW High‐Entropy Alloy With W‐Modulated Local Electronic Structure for Enhanced Electrocatalytic Nitrate Reduction to Ammonia

Electrocatalytic nitrate reduction to ammonia provides a promising strategy for coupling nitrate‐polluted wastewater remediation with distributed ammonia production, but achieving high performance with reasonable selectivity and stability remains challenging. Herein, a W‐modulated NiFeCoRuW high‐entropy alloy catalyst is prepared through microfluidic‐assisted liquid‐phase reduction followed by high‐temperature alloying, with W‐free NiFeCoRu as the control. Structural and surface analyses reveal that W incorporation modifies the diffraction features, particle‐stacking morphology, and core‐level electronic states of the NiFeCoRu matrix, indicating local structural distortion and multimetallic electronic coupling rather than simple compositional addition. Benefiting from the W‐containing multimetallic environment and increased electrochemically accessible sites, NiFeCoRuW achieves an NH 3 Faradaic efficiency of 98.1% and an NH 3 yield rate of 162.65 mg h −1 mg_cat −1 at −0.5 V versus RHE, outperforming reported high‐entropy‐alloy‐based NO 3 RR catalysts. UV–vis colorimetry and NMR cross‐validation support reliable ammonia quantification. In situ DEMS trends and auxiliary free‐energy profiles further suggest that W‐assisted electronic reconstruction favors nitrate activation and promotes deep reduction involving *NOH/*N‐related intermediates while limiting excessive hydrogen‐evolution competition.