La single atoms promoted electrocatalytic ammonia synthesis on few-layer MoS2 via maximum orbital overlap

Electrocatalytic nitrogen reduction reaction (ENRR) provides a promising method for synthetic NH3 under ambient condition. However, this method is faced with the bottleneck of low Faraday efficiency. In this work, maximum orbital overlapping strategy was proposed to select suitable transition metal catalysts for activation of N2 to facilitate ENRR. By the aid of theoretic calculation, it was found that lanthanum (La) had high degree of orbital overlapping with N2 molecular orbital in side-on configuration. La single-atom catalysts were then loaded onto few-layer MoS2 surface (La SACs/FL-MoS2) and used as cathodic catalyst for ENRR. Results showed that introduction of La single-atom greatly improved the Faradaic efficiency of NH3 to 18.2 % with a considerable NH3 yield rate (3.68 μg h−1cm−2) at − 0.25 V (vs. RHE). Further in-situ IR analysis and theoretical calculation revealed the influence of La single-atom on the adsorption and activation of N2. Moreover, the maximum orbital overlap strategy was also applicable to the activation and reduction of N2 on other La transition metals with larger d-orbital size. This study provides a potential solution for the development of high efficiency catalyst for NH3 synthesis by ENRR.