Heteroatom‐doped polymers or carbon nanospheres have attracted broad research interest. However, rational synthesis of these nanospheres with controllable properties is still a great challenge. Herein, we develop a template‐free approach to construct cross‐linked polyphosphazene nanospheres with tunable hollow structures. As comonomers, hexachlorocyclotriphosphazene provides N and P atoms, tannic acid can coordinate with metal ions, and the replaceable third comonomer can endow the materials with various properties. After carbonization, N/P‐doped mesoporous carbon nanospheres were obtained with small particle size (≈50 nm) and high surface area (411.60 m2 g−1). Structural characterization confirmed uniform dispersion of the single atom transition metal sites (i.e., Co‐N2P2) with N and P dual coordination. Electrochemical measurements and theoretical simulations revealed the oxygen reduction reaction performance. This work provides a solution for fabricating diverse heteroatom‐containing polymer nanospheres and their derived single metal atom doped carbon catalysts.

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promising application potential especially in optoelectronics such as light-harvesting systems, organic light emitting diodes, and organic solar cells. [2] Construction of multicomponent assembly systems, in general, could be accomplished through several protocols. To fabricate two-component assemblies, one needs to overcome competitive selfsorting [3,4] of individual self-assemblies to achieve the coassembly. To this end, either strong binding interaction or considerable structural similarity between different components is a prerequisite. For instance, utilizing complementary hydrogen bonding and structural similarity, we have developed amino acid derivative-bipyridine coassembly systems for superchirality control, [5,6] and glutamic analogue coassembly for light harvesting. [7,8] Although some two-component assemblies could be predesigned, the realization of ordered coassembly comprising of three or more components is greatly restricted. [2,9,10] Exponentially increased complexity in three or four-component systems hinders ordered complexation and aggregation. Efforts that have been made in recent years regarding multicomponent systems are concentrated largely on the metallosupramolecular coordination chemistry [11] and dynamic covalent chemistry. [12] Transition metal ions could coordinate with different ligands [13] to form multicomponent metal organic frameworks (MOFs), [14] cages, [11] and molecular polyhedras. [15] Alternatively, orthogonal dynamic covalent bonds like BO and CN that feature easy formation upon dehydration have been employed to prepare metal-free molecular cages [16] and covalent organic frameworks (COFs). [17] Nevertheless, these methods, which place major emphasis on the crystallization process, could hardly be applied to fabricate soft molecular self-assemblies. [18] Utilization of orthogonal noncovalent interactions is a promising method to integrate independent species into coassemblies, with which numerous two or three-component supramolecular polymers have been built. [19] Most of these supramolecular polymeric systems still rely on metal-ligand coordination (such as terpyridine/Fe(III)) [20] and macrocyclic complexation (such as cucurbituril[8]) [21] between components. In many cases, intertwining polymer chains would result in chaotic molecular stacking rather than periodic and ordered molecular organization.Consequently, it is highly challenging to accomplish ordered molecular self-assembly, especially from three or more organic Construction of integrated self-assembly with ordered structures from two or more organic building blocks is currently a challenge, since it suffers from intrinsic systematic complexity and diverse competitive pathways. Here, it is reported that aromatic amino acid building units can be incorporated into two-or three-component coassembly driven primarily by hydrogen bonding interactions without the assistance of metal-ligand and macrocycle-based host-guest interactions. The key strategy is to employ a C 3 -symmetric molecule with alternative hydrogen ...