Microenvironmental Control of Competitive Reaction Pathways: Electrocatalytic Nitrate Synthesis via Managing Interfacial Water Accessibility
Jun Wang, Ruilong Liu, Weikun Ren, Kang Ji, Guixi Wang, Feike Zhang, Xiaoke Li, H. J. Yang, Shiyu Wang, Yingjie Ji, Jingyu Wu, Zhiyu Yang, Yi‐Ming Yan
Abstract
The electrocatalytic nitrogen oxidation reaction (NOR) represents a promising pathway for nitrate (NO 3 – ) production without the harsh conditions and substantial carbon footprint of conventional processes. However, NOR efficiency is fundamentally limited by the competing four-electron oxygen evolution reaction (OER) that dominates at the electrode–electrolyte interface. Here, we demonstrate a microenvironmental control strategy that selectively favors nitrogen oxidation over oxygen evolution by precisely managing the interfacial water accessibility. By constructing a hydrophobic interface on in situ grown Co 3 O 4 nanosheets supported on carbon cloth (CC) through polytetrafluoroethylene (PTFE) coating, we create a controlled reaction microenvironment that strategically limits water diffusion while enhancing nitrogen accessibility at catalytic sites. The optimized Co 3 O 4 –PTFE/CC catalyst achieves a nitrate yield of 0.449 μmol h –1 cm –2 with a Faradaic efficiency of 16.42% at 1.81 V vs RHE in 0.1 M Na 2 SO 4 compared to unmodified Co 3 O 4 /CC (0.241 μmol h –1 cm –2, 8.25%). Through electrochemical in situ Raman spectroscopy combined with molecular dynamics simulations and density functional theory calculations, we reveal that the hydrophobic microenvironment simultaneously suppresses transport of water to active sites while enhancing N 2 adsorption, effectively redirecting the reaction pathway from the OER toward the NOR. This work establishes interfacial microenvironmental engineering as a powerful approach for controlling competitive reaction pathways in three-phase electrocatalytic systems and provides design principles for developing high-performance nitrogen conversion electrocatalysts.