Display omitted •Atomically dispersed (83%) but high-loading (15wt%) Cu on SiO2 was realized.•Covalent CuOSi bonding alters the atomically dispersed and valence states.•The bonding is enabled by a simple urea assistant hydrothermal-deposition method.•CuOSi bonding boosts the intrinsic efficiency by one- to two- orders-of-magnitude.•Transition metals (Cu, Zn, Ni, Co and Mn) can form the bonding via the method. Being a suitable way for achieving the maximum efficiency of atoms, the atomically dispersed metals are playing an ever-increasingly important role in bridging heterogeneous and homogeneous catalysis. It is extremely challenging for dispersing metals in atomic-scales as the applicable high-loading catalysts for industry. The reducible and defective supports or metal surfaces are commonly chosen for anchoring the metals. We here report that atomically-dispersed but high-loading (15wt%) metals were achieved by covalent-bonding to irreducible SiO2 (though silanol groups) which is realized by a simple urea hydrolysis assistant hydrothermal-deposition method. The CuOSi bonding tailors the structural and electronic states of catalyst by maximum of atom efficiency and tuning electronic effects. The intrinsic performance of CO hydrogenation was thus boosted by one- to two- orders-of-magnitude in comparison with impregnated and precipitated catalysts. The choices of metals include Cu, Zn, Ni, Co and Mn, showing potentials for a category of applied materials.