Ru/La2S3 nanorods as an electrocatalyst for efficient N2 fixation under ambient conditions

Abstract

Electrochemical ammonia synthesis has advantages over the conventional Haber–Bosch process in terms of environment friendliness, sustainability, and cleanliness. However, this process is facing challenges such as low ammonia yield and low Faraday efficiency due to the low solubility and the difficulty in activation of nitrogen in aqueous solutions. To overcome these limitations, finding a catalyst of high efficiency, stability, and selectivity is crucial. Inspired by the concept of noble metal doping and two-dimensional layered catalysts, we have designed a novel catalyst for nitrogen reduction by incorporating ruthenium into lanthanum sulfide. In this context, the inclusion of ruthenium serves to optimize the electron transfer interface, enhance the low conductivity of lanthanum sulfide, and increase the number of active sites. Furthermore, the synergistic effect between the ruthenium and lanthanum ions significantly improves the activity of the catalyst. As a catalyst for the N₂ reduction reaction (NRR), Ru/La₂S₃ demonstrates a superior NH₃ formation rate of 19.40 μg h⁻¹ mg_cat⁻¹ and a faradaic efficiency of 7.77% at −0.5 V versus the reversible hydrogen electrode (RHE). These values are significantly higher compared to those of La₂O₃ (1.4%; 12.5 μg h⁻¹ mg_cat⁻¹) and La₂S₃ (2.3%; 10.7 μg h⁻¹ mg_cat⁻¹), and most reported values in this field.