Entropy‐Engineered Prussian Blue Nanocubes Decouple Kinetic Bottlenecks for Selective Nitrate‐to‐Ammonia Conversion in Neutral Media

Abstract

Electrocatalytic nitrate reduction (NO 3 RR) in neutral media offers a sustainable route for decentralized ammonia synthesis, yet remains hindered by sluggish proton‐coupled electron transfer (PCET) and severe *NO 2 − poisoning. In unbuffered media, low proton availability disrupts the Volmer–Heyrovsky equilibrium, while heterogeneous active sites exacerbate competition between *H and nitrogenous intermediates, compromising selectivity. Herein, we deploy configurational entropy as a thermodynamic lever to homogenize interfacial coordination microenvironments and decouple these kinetic bottlenecks. A quinary high‐entropy Prussian blue analog (CNCMZ PBA) is synthesized via a scalable room‐temperature co‐precipitaion route, featuring equimolar Cu, Ni, Co, Mn, and Zn integrated within a single‐phase cubic lattice (Δ S config = 1.619 R). This entropy‐stabilized framework eliminates compositional segregation and establishes uniform MN≡CFe bridging motifs, which collectively flatten the local adsorption energy landscape and synchronize *H generation with multi‐step *NO x hydrogenation. Operando electrochemical impedance spectroscopy, coupled with Bode phase and Distribution of Relaxation Times analysis, quantitatively reveals that this entropy‐engineered microenvironment reduces interfacial charge–transfer resistance by 68% and accelerates the apparent time constant ( τ ). Consequently, the system sustains optimal *H/*NO x surface coverage, effectively bypassing the rate‐determining *NO 2 − conversion step. CNCMZ PBA delivers an exceptional NH 3 yield rate of 5.283 mg h −1 mg cat. −1 and a peak Faraday efficiency of 97.76% at −0.9 V vs. reversible hydrogen electrode in neutral media, with negligible nitrite accumulation and stable operation for over 120 h. This work establishes entropy‐driven coordination homogenization as a generalizable design principle for pH‐dependent PCET pathways, advancing neutral‐media electrocatalysis toward practical nitrogen cycling.