Electron‐Relay Engineering by Magnetothermal Heterostructures for Electrified CH ₄ –CO ₂ Upgrading

Electrified upgrading of CO 2 ‐rich methane streams is an essential yet unresolved challenge for integrating carbon‑negative processing with renewable electricity. Conventional dry reforming of methane fundamentally limits CO 2 utilization to a 1:1 stoichiometric ratio, while coupling with the reverse water–gas shift typically introduces temperature mismatches that force a trade‑off between high CO 2 conversion and strong CH 4 reducibility. Here, we report a magnetothermal heterostructure (MtH) comprising FeCoNiCuRu high‑entropy alloy (HEA) nanoparticles anchored on carbon fibers (CFs) that overcomes this long‑standing limitation. Under inductive eddy‑current heating, the MtH generates non‑equilibrium hot electrons on CFs that spill over across the CF/HEA interface and are directionally relayed toward Ni–Ru dual sites by an electronegativity gradient. This electron‑relay mechanism strengthens the activation of CO 2 and CH 4 , enabling HEA‑MtH to simultaneously achieve near‑complete per‑pass CO 2 conversion (97.0%) and unprecedented CH 4 reducibility (2.99 molCO 2 /molCH 4 ) within a single reactor, outperforming previously reported thermal, electro‑thermal, and tandem catalytic systems. The catalyst rapidly heats to 800°C within 90 s, exhibits excellent compatibility with intermittent renewable electricity, and maintains stable operation for 100 h. This work provides a broadly applicable strategy for one‑step electrified upgrading of compositionally diverse CO 2 ‐rich streams, fundamentally advancing the integration of catalytic CO 2 valorization with renewable energy.