Heterogeneous interface of MnFeSe electrocatalyst for high-performance overall water splitting

Heterogeneous structures with rich phase boundaries are attractive for surface-mediated catalyst applications. Therefore, a practical solution involves constructing heterogeneous materials to maximize the functionality of electrocatalysts. In this study, we assembled a transition metal-based manganese-ferro selenide heterostructure nanosheet, combined with boron-doped carbon quantum dots (B-CQDs) on a foam nickel self-supporting electrocatalyst, using a two-step pyrolysis method (B-CQDs/MnFeSe/NF). The interface between the MnSe and FeSe components of the heterogeneous catalyst modulates the electronic structure, facilitates enhanced charge transfer, and improves structural stability, thereby increasing the efficiency of electrocatalytic water splitting. Consequently, the B-CQDs/MnFeSe/NF heterostructure reduces the hydrogen evolution reaction (HER) over- potential to 89 mV and the oxygen evolution reaction (OER) overpotential to 197 mV. Moreover, this catalyst requires only 1.52 V for the water splitting voltage at a current density of 10 mA cm-2 . This work provides new insights into enhancing the intrinsic activity of overall water-splitting systems with heterogeneous structures.