N2 Electroreduction to NH3 by Selenium Vacancy-Rich ReSe2 Catalysis at an Abrupt Interface.

Vacancy engineering has been proved repeatedly as an adoptable strategy to boost electrocatalysis, while its poor selectivity restricts the usage in nitrogen reduction reaction (NRR) as overwhelming competition from hydrogen evolution reaction (HER). Revealed by density functional theory calculations, the selenium vacancy in ReSe2 crystal can enhance its electroactivity for both NRR and HER by shifting the d-band from -4.42 to -4.19 eV. To restrict the HER, we report a novel method by burying selenium vacancy-rich ReSe2 @carbonized bacterial cellulose (Vr -ReSe2 @CBC) nanofibers between two CBC layers, leading to boosted Faradaic efficiency of 42.5 % and ammonia yield of 28.3 μg h-1  cm-2 at a potential of -0.25 V on an abrupt interface. As demonstrated by the nitrogen bubble adhesive force, superhydrophilic measurements, and COMSOL Multiphysics simulations, the hydrophobic and porous CBC layers can keep the internal Vr -ReSe2 @CBC nanofibers away from water coverage, leaving more unoccupied active sites for the N2 reduction (especially for the potential determining step of proton-electron coupling and transferring processes as *NN → *NNH).