Facilitating Electrochemical Ammonia Production Using an Exfoliated Sr3FeCoO6.72/TiO2 Electrocatalyst: Improved Activity and Charge Transfer Mechanism

Abstract

Ammonia plays a pivotal role as both an industrial and a cornerstone of modern agriculture. However, due to the energy-intensive nature of the conventional Haber–Bosch process and its significant CO₂ emissions, the electrochemical nitrogen reduction reaction driven by renewable energy under ambient conditions has emerged as a promising sustainable alternative. However, its practical implementation remains challenged by the high activation barrier of the N≡N triple bond and the competing hydrogen evolution reaction (HER). To address these limitations, the development of efficient, earth-abundant electrocatalysts is imperative. In this study, we introduce Sr₃FeCoO_6.72 (SFC), as a novel nitrogen reduction reaction (NRR) electrocatalyst. Surface hydroxylation of SFC via probe sonication (ESFC) has been employed to generate hydroxyl groups (─OH) and oxygen vacancies, thereby enhancing nitrogen adsorption and facilitating proton-coupled electron transfer. Further, TiO₂ has been incorporated into the ESFC matrix, with 5 wt% and 10 wt% TiO₂ loadings. The engineered ESFC─TiO₂ promoted interfacial charge transfer and increased the accessibility of active sites. The optimized TESFC10 composite exhibited an ammonia yield rate of 12.8 µg h⁻¹ mg_cat⁻¹ and Faradaic efficiency of 1.1%. These results demonstrate that rationally designing catalysts can foster synergistic interactions between perovskites and semiconductors, enabling efficient and stable electrochemical synthesis of NH₃.