Autogenous force-mediated assembly: A general strategy for constructing single-atom architectures in hierarchical hybrid electrocatalysts

The design of efficient and pH-universal ruthenium (Ru) single-atom catalysts (SACs) remains a pivotal challenge for hydrogen economy systems. Here, inspired by tubular capillary phenomena, a novel approach is introduced—autogenous force-mediated assembly—enabled by a unique asymmetric N-doped carbon nanotubes (NCNTs) scaffold with a Co-embedded sealed end. The confined geometry drives a spontaneous, directional outward migration of Co 2+ species at room temperature, which deposit as amorphous or poorly crystalline cobalt-based compounds at the outer surface while concurrently capturing and stabilizing Ru species in single-atom configurations. And these precursors transform into well-crystallized Co 3 O 4 anchored with Ru single-atom upon calcination. This process yields a precisely organized three-dimensional architecture where metallic Co nanoparticles remain confined within the NCNTs, while atomically dispersed Ru sites are firmly anchored on the exterior Co 3 O 4 lattice. The gradual migration-deposition process is inherently self-limiting, ensuring uniform dispersion of Ru single-atoms (SAs). The resulting lattice confinement induces a strong electronic metal-support interaction (EMSI), which effectively suppresses atomic aggregation and optimizes the electronic structure of the active sites. The integrated system—coupling the conductive Co@NCNT with the EMSI-enhanced Ru-Co 3 O 4 interface—delivers outstanding hydrogen evolution reaction performance. This work establishes a generalizable synthesis paradigm that leverages internally generated forces for the precise spatial organization of active components, presenting a versatile route toward high-performance SACs for sustainable energy conversion.