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 (E1/2) of 0.92 V, which is superior over the catalysts with a single junction and the state‐of‐the‐art Pt/C (E1/2 = 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.

Microenvironment Tailoring of NiCo Alloys Coupled with FePc as Efficient Bifunctional Catalysts for High-Rate Zn-Air Batteries

“…Due to the transfer of electrons from FePc to the NiCo alloy, the NiCo alloy with an electron-rich state shows a more metallic feature, which is beneficial to accelerate the kinetic transfer process . In Figure g, the Fe 2p spectra of FePc/NiCo/CNT can be well fitted into five peaks, assigned to Fe 3+ (725, 713 eV), Fe 2+ (722, 709 eV), and the satellite peak (717 eV), respectively. , Unexpectedly, all peaks of Fe 2p spectra have a positive sign, indicating the electron-deficient state of FePc and the electronic interaction between FePc and the NiCo alloy. , For the N 1s spectra of Figure h, the four characteristic peaks are ascribed to the pyridinic (399 eV), pyrrolic/Fe–N (400 eV), graphitic (402 eV), and N-oxide (405 eV) groups . After coupling with FePc, the Fe–N peak of the FePc/NiCo/CNT catalyst shifts toward the lower binding energy direction, which proves that coupling with the NiCo alloy can change the local electronic structure near the Fe–N active site as the primary catalytic site in the ORR process …”

“…39 In Figure 2g, the Fe 2p spectra of FePc/NiCo/CNT can be well fitted into five peaks, assigned to Fe 3+ (725, 713 eV), Fe 2+ (722, 709 eV), and the satellite peak (717 eV), respectively. 40,41 Unexpectedly, all peaks of Fe 2p spectra have a positive sign, indicating the electron-deficient state of FePc and the electronic interaction between FePc and the NiCo alloy. 42,43 For the N 1s spectra of Figure 2h, the four characteristic peaks are ascribed to the pyridinic (399 eV), pyrrolic/Fe−N (400 eV), graphitic (402 eV), and N-oxide (405 eV) groups.…”