Amorphous NiSb2O6–x nanofiber: A d-/p-block Janus electrocatalyst toward efficient NH3 synthesis through boosted N2 adsorption and activation

Abstract

The electrochemical N2 reduction reaction (NRR) is greatly challenged by relatively low faradaic efficiency (FE) owing to fierce competition from the H2 evolution reaction (HER) suffered by the current transition-metal electrocatalysts (d-block elements). Considering the unique electronic structure of group-VA pnictogens (p-block elements) that is complementary to d-block elements in HER suppression, we report a conceptually new Janus electrocatalyst to tackle the selectivity challenge. Specifically, an amorphous NiSb2O6–x nanofiber is synthesized, in which Ni and Sb contribute to a synergistic catalysis pathway for inhibiting the two-electron transfer process of HER as well as activating the adsorbed N2 molecules. Moreover, amorphization is able to produce more oxygen vacancies, thus mimicking the “π back-donation’’ process to promote the NRR performance. Benefiting from this coupled element design and amorphization strategy, the amorphous NiSb2O6–x nanofiber significantly outperforms either component (NiO or Sb2O4) as well as its crystalline counterparts in terms of NH3 yield and FE.