Mo-doped SnS2 with rich S-vacancies for highly efficient electrocatalytic N2 reduction: the critical role of Mo-Sn-Sn trimer

Vacancy engineering and heteroatom doping are two effective approaches to tailor the electronic structures of the catalysts for improved electrocatalytic activity. Herein, these two approaches were rationally combined to modulate the structure of SnS2 toward N2 reduction reaction (NRR) by means of Mo-doping, which simultaneously induced the generation of rich S-vacancies (Vs). The developed Mo-doped SnS2 nanosheets with enriched Vs presented a conspicuously enhanced NRR activity with an NH3 yield of 41.3 μg h−1 mg−1 (-0.5 V) and a Faradaic efficiency of 20.8% (-0.4 V), which was among the best SnS2-based NRR catalysts to date. Mechanistic studies revealed that the co-presence of Mo dopant and Vs enabled the creation of Mo-Sn-Sn trimer catalytic site, capable of strongly activating N2 for even the cleavage of N≡N triple bond to N=N double bond at N2 adsorption stage, consequently leading to downhill process of the first hydrogenation step and largely reduced energy barrier.