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

Electrochemical reduction of N (NRR) offers a sustainable approach for ammonia (NH) synthesis, serving as a complementary to the traditional emission- and energy-intensive Haber-Bosch process. However, it faces challenges in N 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 TiCT for NRR. These experimental and theoretical calculation results demonstrate that 1) ultrafine Ru NCs dispersed on the TiCT surface form paired active sites for N 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 accumulation while repelling HO diffusion to the active sites on the TiCT surface, thereby leading to an increased N concentration and suppressed HER. As a result, an exceptionally high NH yield rate of 33.5 µg h mgcat and Faradaic efficiency of 65.3% are obtained at -0.25 V versus reversible hydrogen electrode (RHE) in 0.1 m NaSO, outperforming those previously reported TiCT-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.