p-Block Metal Oxide as an Efficient Electrocatalyst for Boosting Ambient Ammonia Synthesis

Abstract

The electrocatalytic nitrogen reduction reaction (NRR) offers a promising alternative to the traditional Haber−Bosch process for producing NH 3 under ambient conditions. Designing efficient electrocatalysts is crucial for achieving an active and selective NRR, as these catalysts can lower the energy barrier and modify the rate-determining step. Catalysts featuring Lewis acid active centers are particularly effective for NRR due to their ability to facilitate N 2 adsorption and subsequent reduction. Herein, we have chosen a pblock element (Al) as the active center due to its Lewis acidity and synthesized the material, zinc aluminate (ZnAl 2 O 4 , ZAO). Al−O can participate in bonding and antibonding interactions with N 2 molecules and activates for the reduction. The ZAO electrocatalyst attained a Faradaic efficiency of 45.9% at −0.3 V versus the reversible hydrogen electrode (RHE) for selective NH 3 production in a 0.1 M Na 2 SO 4 electrolyte. Furthermore, in situ attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy confirmed the formation of intermediates during the NRR pathway. This research offers a new approach for designing efficient catalysts using p-block elements, enhancing the electrocatalytic NRR for ammonia synthesis.