Phase-RegulatedFeSe₂@(1T-2H)-MoSe₂ Derived from Anderson-TypePolyoxometalate as an EfficientElectrocatalyst for the Nitrogen Reduction Reaction

The ambient electrolytic nitrogen reduction reaction (e-NRR) has been extensively studied as a potential alternative to the capital and energy-intensive Haber–Bosch process for ammonia production. However, the design and construction of highly effective catalysts for e-NRR are still extremely challenging. In this work, a series of phase-regulated composites FeSe₂@(1T-2H)-MoSe₂-<i>X</i> (<i>X</i> represents the reaction time of 4, 6, and 8 h) were designed and synthesized by using the Anderson-type polyoxometalate as a preassembly platform, together with phase engineering. The progressive transformation from 2H-MoSe₂ to 1T-MoSe₂ can be implemented in FeSe₂@(1T-2H)-MoSe₂-<i>X</i> by inserting Fe and changing the reaction time. The electrocatalytic performances have been significantly improved thanks to the synergistic effect of FeSe₂, 2H-MoSe₂, and 1T-MoSe₂, which gives rise to a very high electron transfer capability and more active sites. In particular, composite FeSe₂@(1T-2H)-MoSe₂-6 h (with 69.7% of 1T-MoSe₂ and 29.3% of 2H-MoSe₂) exhibits an optimal NH₃ yield rate of 28.31 μg h^–1 mg_cat^–1 and a Faradaic efficiency of 32.01%. Density functional theory calculations show that multiphasic FeSe₂@(1T-2H)-MoSe₂-6 h with appropriate content of 1T-MoSe₂ can significantly reduce the energy of the rate-determining step (*N₂ to *N₂H) and inhibit the process of the hydrogen evolution reaction, thereby further increasing the production of NH₃.