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.