Reactivity of nitrogen atoms from Zif-8 structure deposited over Ti₃C₂ MXene in the electrochemical nitrogen reduction reaction

Abstract

The electrochemical nitrogen reduction reaction (NRR) to produce NH₃ is the most efficient, eco-friendly and cost-effective alternative to the Haber-Bosch process. It is crucial to investigate and develop electrocatalysts selective for NH₃ synthesis. In recent studies, the Ti₃C₂ MXene has emerged as a highly promising electrocatalyst for the NRR process. In this work, we explore the effect of Zif-8 addition over MXene sheets in order to control the rate of hydrogen evolution reaction (HER). Despite the better result obtained for Zif-8@Ti₃C₂ (3.0 μg NH₃ g_cat^-1 h^-1 at -0.55 V/RHE), the ammonia produced when using Zif-8@Ti₃C₂ as cathode material is shown to be originated from nitrogen atoms contained in the Zif-8 structure instead of those of N₂. The results shed light to the need to fully understand the N₂ electroreduction process over <i>N</i>-containing electrocatalysts.