In situ grown Fe3O4 particle on stainless steel: A highly efficient electrocatalyst for nitrate reduction to ammonia

Abstract

NH 3 is an essential feedstock for fertilizer synthesis. Industry-scale NH 3 synthesis mostly relies on the Haber-Bosch method, however, which suffers from massive CO 2 emission and high energy consumption. Electrocatalytic NO 3 − reduction is an attractive substitute to the Haber-Bosch method for synthesizing NH 3 under mild conditions. As this reaction will produce a variety of products, it highly desires efficient and selective electrocatalyst for NH 3 generation. Here, we report in situ grown Fe 3 O 4 particle on stainless steel (Fe 3 O 4 /SS) as a high-efficiency electrocatalyst for NO 3 − reduction to NH 3 . In 0.1 M NaOH with 0.1 M NaNO 3 , such Fe 3 O 4 /SS reaches a remarkable Faradaic efficiency of 91.5% and a high NH 3 yield of 10,145 µg·h −1 ·cm −2 at −0.5 V vs. reversible hydrogen electrode (RHE). Furthermore, it owns robust structural and electrochemical stability. This work provides useful guidelines to expand the scope of metallic oxide electrocatalysts for NH 3 synthesis. The catalytic mechanism is uncovered and discussed further by theoretical calculations.