Interfacial Oxophilicity Engineering Modulates Surface Hydroxyl Chemistry for Enhanced Electrocatalytic Nitrogen‐to‐Nitrate Conversion

Abstract

ABSTRACT Electrocatalytic nitrogen oxidation offers an ambient route to nitrate, but the competition between oxygenated intermediates and N 2 adsorption limits efficient nitrate formation. Here, we construct a La 2 O 3– Co 3 O 4 heterojunction to regulate the interfacial oxygen/hydroxyl environment through differential oxophilicity. At 2.01 V vs. the reversible hydrogen electrode (RHE), La 2 O 3 –Co 3 O 4 delivers a nitrate yield rate of 47.38 µg h −1 mg cat −1 with Faradaic efficiency(NO 3 − ) of 18.77%, outperforming the individual oxides and the corresponding physical‐mixture control. Potential‐dependent O 1sX‐ray photoelectron spectroscopy (XPS), quasi‐in situ Co 2p XPS, in situ vibrational spectroscopy, and density functional theory (DFT) reveal a distinct interfacial oxygen/hydroxyl response and preferential thermodynamic stabilization of La‐associated hydroxyl configurations under anodic conditions. These results link the enhanced nitrate formation to interfacial hydroxyl regulation and identify oxophilicity engineering as a useful strategy for electrocatalytic nitrogen oxidation.