Dual Regulation of Electronic Structure and Hydrogen Distribution through Co Single-Atom-Functionalized Supports for Efficient Ru-Catalyzed Ammonia Synthesis

Abstract

Under mild reaction conditions, ammonia synthesis over Ru catalysts is severely constrained by hydrogen poisoning because excessive surface hydrogen blocks the Ru B5 sites required for efficient N2 activation. To overcome this challenge, we design an atomically functionalized support by anchoring isolated Co single atoms at framework sites of K-modified KL zeolite, creating a dual-function support. The Co single atoms serve as hydrogen-accepting sites that continuously remove surface H atoms from Ru via hydrogen spillover, i.e., spatial regulation of surface hydrogen. Moreover, they indirectly strengthen the electron donation from framework K to Ru for N2 activation, without any direct Co → Ru charge transfer, thereby enhancing both the availability and the intrinsic activity of Ru B5 sites for efficient N2 dissociation. This cooperative mechanism is collectively revealed by comprehensive kinetic analyses, operando spectroscopy, isotope-exchange measurements, chemisorption studies, and density functional theory (DFT) calculations. Consequently, Ru/Co1–KL achieves a near-equilibrium ammonia synthesis rate of 65.3 mmol g–1 h–1 at 400 °C and 1 MPa and maintains stable performance for over 1500 h. This work demonstrates that atomic support functionalization can spatially decouple competing adsorption processes at catalytic interfaces, offering an effective strategy for overcoming site-blocking limitations in heterogeneous catalysis.