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) overpotential 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. The novel B-CQDs/MnFeSe/NF catalyst was prepared using the solvothermal method, exhibiting excellent catalytic activity and stability in the overall water splitting reaction. [Display omitted] • B-CQDs/MnFeSe/NF catalyst was prepared using two-step solvothermal method. • Synergies of MnSe and FeSe promote electron transfer to enhance HER/OER activity. • Heterogeneous structure offers more active sites and transport channels for HER/OER. • B-CQDs/MnFeSe/NF.||B-CQDs/MnFeSe/NF shows 1.52 V operating voltage at 10 mA cm−2. • The overall water splitting on B-CQDs/MnFeSe/NF is nearly 100% Faraday efficiency. [ABSTRACT FROM AUTHOR]