The Crucial Role of Interlayer Spacing in MXene Electrocatalysts for Enhanced Nitrogen Reduction Reaction

ABSTRACT The electrocatalytic nitrogen reduction reaction (eNRR) presents a sustainable alternative to the energy‐demanding Haber–Bosch process used for ammonia synthesis. Two‐dimensional (2D) transition metal carbides and nitrides (MXenes) have been identified as promising electrocatalysts for NRR because of their distinctive electronic structures and adjustable surface properties. Nonetheless, achieving high levels of activity and selectivity continues to pose a significant challenge. This review emphasizes the important role of MXene interlayer spacing in enhancing NRR performance. By accurately controlling the distance between MXene layers, the accessibility of active sites, the adsorption and activation of dinitrogen (N 2 ) can be optimized, and the electronic structure can be adjusted to promote the desired proton‐coupled electron transfer (PCET) pathways while inhibiting the competing hydrogen evolution reaction (HER). There are various methods for adjusting the interlayer spacing, including intercalation with various organic molecules, metal ions, or polymers, along with the creation of restacked or exfoliated MXene structures. Additionally, the review investigates the connection between interlayer distance and important NRR performance metrics, such as catalytic activity, Faradaic efficiency, and ammonia yield. Gaining insights into and effectively manipulating the MXene interlayer spacing offers a rational approach for designing highly efficient and selective electrocatalysts for sustainable ammonia production.