In‑Situ Visualization of ZIF‑L‑to‑Nanocarbon Transformation and Nanoscale Origins of ORR Activity

Metal-organic frameworks are versatile precursors for nanostructured, heteroatom‑doped carbons, yet the nanoscale processes that couple crystalline collapse, short‑range reorganization, and electrocatalytic function remain obscure. Here, we elucidate the spatiotemporal transformation of 2D leaf‑shaped ZIF‑L into N‑doped carbons by integrating in‑situ TEM and in‑situ XRD with synchrotron X‑ray pair distribution function analysis and electron energy‑loss spectroscopy. Controlled heating to 650 °C visualizes layer‑selective framework collapse decoupled from electron‑beam artifacts, while ex‑situ pyrolysis (700-1100 °C) maps the emergence of amorphous nanodomains, temperature‑dependent ligand scission, migration of Zn-N species, and progressive Zn removal. The resulting carbons exhibit tunable nanoscale porosity and nitrogen speciation that govern oxygen reduction reaction (ORR) performance, with materials formed at 1000 °C delivering the highest activity in our temperature series. Correlating thermal protocol, local structure/chemistry, and electrochemical metrics establishes a temperature-structure-activity relationship that rationalizes the formation of ORR‑active sites and mass‑transport‑favorable architectures. Beyond ZIF‑L, the mechanistic framework-real‑time imaging of collapse, tracking of short‑range order, and chemistries of mobile Zn-N motifs-provides general guidance for the bottom‑up design of MOF‑derived nanocarbons. This work highlights how in‑situ nanoscale probes deconvolute beam and thermal effects, reveal diffusion‑mediated reorganization within amorphous intermediates, and enable the rational thermal engineering of carbon electrocatalysts with predictable active‑site chemistry and hierarchical porosity.