Fe-doped SnO2 nanosheet for ambient electrocatalytic nitrogen reduction reaction

Ammonia plays a vital role in the development of modern agriculture and industry. Compared to the conventional Haber-Bosch ammonia synthesis in industry, electrocatalytic nitrogen reduction reaction (NRR) is considered as a promising and environmental friendly strategy to synthesize ammonia. Here, inspired by biological nitrogenase, we designed iron doped tin oxide (Fe-doped SnO2) for nitrogen reduction. In this work, iron can optimize the interface electron transfer and improve the poor conductivity of the pure SnO2, meanwhile, the synergistic effect between iron and Sn ions improves the catalyst activity. In the electrocatalytic NRR test, Fe-doped SnO2 exhibits a NH3 yield of 28.45 mu g.h(-1).mg(cat)(-1), which is 2.1 times that of pure SnO2, and Faradaic efficiency of 6.54% at -0.8 V vs. RHE in 0.1 M Na2SO4. It also shows good stability during a 12-h long-term stability test. Density functional theory calculations show that doped Fe atoms in SnO2 enhance catalysis performance of some Sn sites by strengthening N-Sn interaction and lowering the energy barrier of the rate-limiting step of NRR. The transient photovoltage test reveals that electrons in the low-frequency region are the key to determining the electron transfer ability of Fe-doped SnO2.