Interphase-Engineering of Fe-Doped α-Mo <b> ₁₅ </b> Se <b> ₁₉ </b> /CoSeO <b> ₃ </b> Nanosheet Arrays via In Situ Oxidation-Selenization on Conductive Carbon Fabric for Efficient Bifunctional Water Splitting

The design of a cost-effective, sustainable bifunctional electrocatalyst from earth-abundant materials for the advancement of water splitting is urgently needed. Herein, we report an interphase-engineered Fe-doped α-Mo 15 Se 19 /CoSeO 3 nanosheet array on carbon fabric (CF) through an in situ oxidation-selenization strategy, employed as a self-supported bifunctional electrode for overall water splitting. Quantitative X-ray photoelectron spectroscopy (XPS) analysis reveals that Fe incorporation induces distinct electronic modulation and interfacial charge redistribution. This bidirectional electronic interaction optimizes the adsorption energetics of reaction intermediates and significantly promotes charge-transfer kinetics. Consequently, the optimized heterostructure exhibits exceptional bifunctional activity, requiring overpotentials of only 207 mV at 20 mA cm –2 for the oxygen evolution reaction (OER) and 98 mV at 10 mA cm –2 for the hydrogen evolution reaction (HER). When integrated into an alkaline water electrolyzer, the system delivers a benchmark cell voltage of 1.52 V at 10 mA cm –2 and maintains stable operation for 100 h at 50 mA cm –2 with a minor voltage increase of only 9.6%. The results show that interfacial engineering and electronic modulation are effective tools for regulating catalytic activity and stability. This work offers a viable foundation for developing high-performance, noble-metal-free bifunctional electrocatalysts for alkaline water splitting.