Modulating Nitrogen Adsorption Mode and Microenvironment of Active Sites for Boosting Electrochemical Nitrogen Reduction

Abstract Electrochemical reduction of N ₂ (NRR) offers a sustainable approach for ammonia (NH ₃ ) synthesis, serving as a complementary to the traditional emission‐ and energy‐intensive Haber–Bosch process. However, it faces challenges in N ₂ activation and competing with pronounced hydrogen evolution reaction (HER). Herein an efficient electrocatalyst comprised of ultrafine Ru nanoclusters (NCs) confined by a hydrophobic molecular layer is developed on the surface of 2D Ti ₃ C ₂ T _x for NRR. These experimental and theoretical calculation results demonstrate that 1) ultrafine Ru NCs dispersed on the Ti ₃ C ₂ T _x surface form paired active sites for N ₂ chemisorption in a unique tilted configuration with low‐energy activation 2) the hydrophobic molecular layer modulates the local microenvironment surrounding catalytically active sites, enabling efficient N ₂ accumulation while repelling H ₂ O diffusion to the active sites on the Ti ₃ C ₂ T _x surface, thereby leading to an increased N ₂ concentration and suppressed HER. As a result, an exceptionally high NH ₃ yield rate of 33.5 µg h ⁻¹ mg ⁻¹ cat and Faradaic efficiency of 65.3% are obtained at −0.25 V versus reversible hydrogen electrode (RHE) in 0.1 m Na ₂ SO ₄ , outperforming those previously reported Ti ₃ C ₂ T _x ‐derived electrocatalysts. This work provides a valuable strategy for the rational design of advanced electrocatalysts by manipulating active sites and local microenvironments for efficient electrocatalysis.