Triggering in-plane defect cluster on MoS2 for accelerated dinitrogen electroreduction to ammonia

Electrochemical nitrogen reduction reaction (eNRR) is an alternative promising manner for sustainable N2 fixation with low-emission. The major challenge for developing an efficient electrocatalyst is the cleaving of the stable NN triple bonds. Herein, we design a new MoS2 with in-plane defect cluster through a bottom-up approach for the first time, where the defect cluster is composed of three adjacent S vacancies. The well-defined in-plane defect clusters could contribute to the strong chemical adsorption and activation towards inert nitrogen, achieving an excellent eNRR performance with an ammonia yield rate of 43.4 ± 3 μg h−1 mgcat.−1 and a Faradaic efficiency of 16.8 ± 2% at −0.3 V (vs. RHE). The performance is much higher than that of MoS2 with the edge defect. Isotopic labeling confirms that N atoms of produced NH4+ originate from N2. Furthermore, the in-plane defect clusters realized the alternate hydrogenation of nitrogen in a side-on way to synthesize ammonia. This work provides a prospecting strategy for fine-tuning in-plane defects in a catalyst, and also promotes the progress of eNRR.