Interface Hydrophobic Engineering on Copper Species‐Modified Ga 2 O 3 Nanofibers for Enhanced Nitrate Electroreduction

ABSTRACT Suppressing the competing hydrogen evolution reaction (HER) and inefficient mass transport remains a major obstacle for electrocatalytic nitrate reduction reactions (NO 3 RR), particularly in the low nitrate concentration industrial wastewater. Nevertheless, previous studies primarily focus on optimizing catalyst intrinsic activity, yet achieving high selectivity and activity simultaneously remains challenging. Herein, we report a dual coordination strategy to modulate the surface electronic structure and interfacial microenvironment of nanofiber catalysts, thereby enabling simultaneous HER suppression and enhancing electrocatalytic activation of nitrate (). Specifically, the reduced copper species‐modified gallium oxide (r‐Cu/Ga 2 O 3 ) nanofiber catalyst with abundant Cu species and oxygen vacancies is obtained by thermal reduction of the oxide precursor via in situ exsolution method, which enhances the nitrate adsorption and activation. Moreover, a low‐surface‐energy monolayer interface is assembled on nanofiber surface to modulate the reaction microenvironment, restricting proton transfer to active sites and kinetically inhibiting HER. Therefore, the prepared r‐Cu/Ga 2 O 3 ‐SAM nanofiber catalyst achieves NH 3 yield of 22.36 mg h −1 mg −1 at −1.15 V and a FE of 95.48% at −1.05 V versus RHE in 20 mM solution. We expect that these findings can provide novel insights and guidance for designing effective electrocatalytic NO 3 RR catalysts under low NO 3 − concentration.