Deep Electronic State Regulation through Unidirectional Cascade Electron Transfer Induced by Dual Junction Boosting Electrocatalysis Performance

Abstract Unidirectional cascade electron transfer induced by multi‐junctions is essential for deep electronic state regulation of the catalytic active sites, while this advanced concept has rarely been investigated in the field of electrocatalysis. In the present work, a dual junction heterostructure (FePc/L‐R/CN) is designed by anchoring iron phthalocyanine (FePc)/MXene (L‐Ti₃C₂‐R, R═OH or F) heterojunction on g‐C₃N₄ nanosheet substrates for electrocatalysis. The unidirectional cascade electron transfer (g‐C₃N₄ → L‐Ti₃C₂‐R → FePc) induced by the dual junction of FePc/L‐Ti₃C₂‐R and L‐Ti₃C₂‐R/g‐C₃N₄ makes the Fe center electron‐rich and therefore facilitates the adsorption of O₂ in the oxygen reduction reaction (ORR). Moreover, the electron transfer between FePc and MXene is facilitated by the axial Fe─O coordination interaction of Fe with the OH in alkalized MXene nanosheets (L‐Ti₃C₂‐OH). As a result, FePc/L‐OH/CN exhibits an impressive ORR activity with a half‐wave potential (E_1/2) of 0.92 V, which is superior over the catalysts with a single junction and the state‐of‐the‐art Pt/C (E_1/2 = 0.85 V). This work provides a broad idea for deep regulation of electronic state by the unidirectional cascade multi‐step charge transfer and can be extended to other proton‐coupled electron transfer processes.