Beyond Surface Area: Synergistic Nanocasting and Reactor Engineering Unleash Perovskite's Full Potential in Nitrate Electroreduction.

The sluggish kinetics of perovskite electrocatalysts in nitrate electroreduction (ERN), primarily due to their inherently low surface areas prepared by conventional synthesis methods, has hindered their practical application. Here, we present a dual-strategy breakthrough: (1) a nanocasting approach using SBA-15 templates to synthesize mesoporous LaCoO3 with a record-high specific surface area (137.42 m2 g-1, 42-fold higher than sol-gel-derived bulk LaCoO3), and (2) an innovative electrocatalytic filtration reactor engineered to overcome mass transfer limitations in traditional flow-by systems. The mesoporous LaCoO3 exhibits superior NO3--N removal (1.44×) and NH3 yield rates (2.47×) compared to its bulk counterpart in a typical flow-by mode reactor, yet these enhancements fall short of the surface area enhancement ratio, revealing hidden interfacial mass transfer bottlenecks. Through computational fluid dynamics (CFD) simulations, we demonstrate that typical flow-by mode reactor restricts reactant access to surface-bound catalyst layers, while our flow-through reactor enables significantly enhanced electrolyte-catalyst interaction, amplifying performance by 1.67 and 2.26 times for bulk and mesoporous LaCoO3, respectively. This work emphasizes the critical synergy between nanostructure engineering and eliminating mass transfer limitations to unlock the untapped potential of electrocatalysts.