Developing high-performance nitrogen reduction reaction (NRR) electrocatalysts is an ongoing challenge. Herein, we report a pyrolysis-free synthetic method for introducing ordered quasiphthalocyanine N-coordinated transition metal (Ti, Cu, or Co) centers into a conjugated two-dimensional (2D) covalent organic framework (COF) for enhanced NRR performance. Detailed experiments and characterizations revealed that the NRR activity of Ti-COF was clearly better than that of Cu-COF and Co-COF, because of the superior abilities of Ti metal centers in activating inert N 2 molecules and suppressing the hydrogen evolution reaction (HER). The resulting Ti-COF exhibits a high NH 3 yield of 26.89 μg h −1 mg −1 cat. and a Faradaic efficiency of 34.62% for NRR. Density functional theory (DFT) calculations verify that Ti-COF can effectively adsorb and activate N 2 molecules and inhibit HER compared with Cu-COF, Co-COF, and pristine COF catalysts. This work opens a new avenue for developing 2D-COF materials that contain abundant coordinated transition metal centers toward electrocatalytic NRR.

Nitrogen‐coordinated single‐cobalt‐atom electrocatalysts, particularly ones derived from high‐temperature pyrolysis of cobalt‐based zeolitic imidazolate frameworks (ZIFs), have emerged as a new frontier in the design of oxygen reduction cathodes in polymer electrolyte fuel cells (PEFCs) due to their enhanced durability and smaller Fenton effects related to the degradation of membranes and ionomers compared with emphasized iron‐based electrocatalysts. However, pyrolysis techniques lead to obscure active‐site configurations, undesirably defined porosity and morphology, and fewer exposed active sites. Herein, a highly stable cross‐linked nanofiber electrode is directly prepared by electrospinning using a liquid processability cobalt‐based covalent organic polymer (Co‐COP) obtained via pyrolysis‐free strategy. The resultant fibers can be facilely organized into a free‐standing large‐area film with a uniform hierarchical porous texture and a full dispersion of atomic Co active sites on the catalyst surface. Focused ion beam‐field emission scanning electron microscopy and computational fluid dynamics experiments confirm that the relative diffusion coefficient is enhanced by 3.5 times, which can provide an efficient route both for reactants to enter the active sites, and drain away the produced water efficiently. Resultingly, the peak power density of the integrated Co‐COP nanofiber electrode is remarkably enhanced by 1.72 times along with significantly higher durability compared with conventional spraying methods. Notably, this nanofabrication technique also maintains excellent scalability and uniformity.

Transition metal‐nitrogen‐carbon (M‐N‐C) catalysts with CoN4 centers have attracted great attention as a potential alternative to precious metal catalysts for bifunctional oxygen electrocatalysis. However, the asymmetric charge environment of the active site of MN4 obtained by conventional pyrolysis strategy makes the unbalanced adsorption of oxygen molecules, which restricts the activities of both oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). Herein, a series of well‐defined quasi‐phthalocyanine conjugated 2D covalent organic polymer (COPBTC‐M) is developed with MN4+4 active sites through a pyrolysis‐free strategy. Compared to CoN4 site, the additional subcentral N4 atoms in MN4+4 site in COPBTC‐Co catalyst balance the charge environment and form a symmetric charge distribution, which changes the antibonding orbital of the active metal and regulate the oxygen species adsorption, thus improving the activity of the bifunctional oxygen electrocatalysis. In Silico screening demonstrates that cobalt has the best ORR and OER activity for COPBTC‐M with MN4+4 sites, which can be attributed to the fewer anti‐bonding orbital below the Fermi level, which weakens the oxygen species adsorption. Both theoretical and experimental results verify that the COPBTC‐Co possesses unique CoN4+4 active sites and the harmonious coordinating environment can lead to superior bifunctional oxygen catalytic activity with a high bifunctional oxygen catalytic activity (ΔE [Ej10 – E1/2] = 0.76 V), which is comparable with the benchmark Pt/C‐IrO2 pairs. Accordingly, the as‐assembled Zn–air battery exhibits a maximum power density of 157.7 mW cm −2 with stable operation for >100 cycles under an electric density of 10 mA cm −2. This study provides a characteristic understanding of the intrinsic active species toward MNx centers and could inspire new avenues for designation of advanced bifunctional electrocatalysts that catalyze ORR and OER processes simultaneously.

Regulating the p-orbital valence electrons of atomically dispersed main-group metals to improve the inherent electrocatalytic activity has attracted extensive concerns. Herein, we designed and synthesized an atomically dispersed Sb−SeNC catalyst containing SbN 2 C 2 and SeC 2 structures, which have been identified by X-ray absorption spectroscopy and density functional theory (DFT) calculations. Sb−SeNC exhibits a high activity for the oxygen reduction reaction (ORR), and a Sb− SeNC-based flexible solid-state zinc−air battery (ZAB) can work efficiently at −40 °C, with a peak power density of 54.1 mW cm −2 and a rate discharge operation of about 44 h. DFT calculations further confirm the long-range regulation mechanism of the SeC 2 moiety for the ORR of SbN 2 C 2 and obtain the volcano relationship of U onset vs the Se−N distance. When the Se−N distance is 7.4 Å, the adsorption ability of active site Sb can be regulated to an optimal state related to the RDS: *O → *OH, while the smaller Se−N distance in short-range would lead to the excessive attenuation of adsorption ability of active site and decrease of ORR activity, which therefore yields the long-range regulation effect of Se doping on the ORR activity of SbN 2 C 2 . This long-range regulation strategy may provide a promising approach to boost the catalytic activity of main-group metal catalysts to achieve its application in ultralow-temperature solid-state ZABs.

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