Self-Templated Engineering of W3N4 Active Sites on CTF-Derived Tungsten Catalysts: Synergistic Regulation of Mass Transfer, Reaction Pathway, and Oxygen Reduction Activity.

The urgent demand for Pt-free oxygen reduction catalysts drives exploration of tungsten-based alternatives, motivated by its Pt-mimetic valence electron configuration and optimal oxygen binding energy (ΔEO ≈ - 2.05 eV) revealed in oxygen reduction reaction (ORR) volcano plots. Herein, a hierarchical W3N4-doped catalyst has been engineered through dual-stage thermal activation of covalent triazine framework (CTF)-tungstate complexes, where W precursors serve dual roles as self-sacrificing templates and active site generators. In-depth discussions via distribution of relaxation time (DRT) analysis elucidates that the hierarchical pore structure and active sites of WNNP-C demonstrate ∼90% reduction in relaxation time (τ = 0.18 vs 1.6 s of WNOSAC-C) at half potential and achieve a 0.83 V half-wave potential (E1/2) approaching Pt/C (0.865 V) in 0.1 M KOH coupled with exceptional methanol tolerance. The mechanistic analysis demonstrates that the enhanced electrical conductivity of the catalyst support facilitates the desorption of *OH intermediates by overcoming their elevated energy barrier, which preferentially promotes the 4e- ORR pathway and consequently improves the overall ORR performance. Moreover, the WNNP-C assembled zinc-air battery delivers 839 mAh gZn-1 specific capacity and over 140 h of stability at a discharge current density of 5 mA/cm2, validating the strategy's effectiveness in synchronizing porous architectures with W3N4 active centers. This work provides a paradigm for unlocking catalytic potential in traditionally inert transition metals through synergistic coordination pyrolysis engineering.