Accelerated HER kinetics via electron-deficient Ni and electron-enriched Se sites by dual Fe and Mn doping for highly efficient hydrogen production

Abstract

The rational design of efficient and stable non-noble electrocatalysts for the hydrogen evolution reaction (HER) is vital but still challenging. Doping strategies have recently been explored for Ni-based selenides, but the synergistic modulation of dual-valence states, especially by coupling with low-valence Fe and high-valence Mn in Ni_0.85Se, has rarely been reported; additionally, their roles in promoting HER dynamics remain unclear. Herein, we demonstrate the facile synthesis of Fe and Mn dual-doped Ni_0.85Se (Fe/Mn-Ni_0.85Se) on Ni foam (NF) by electrodeposition, followed by selenization for the HER. Benefiting from the co-modulation of Fe and Mn, the electronic environment of Ni and Se in Fe/Mn-Ni_0.85Se is finely tuned, leading to accelerated charge transfer and high HER performance. The resulting Fe/Mn-Ni_0.85Se exhibits a small overpotential of 137.3 mV at an ampere level of 2 A cm⁻², with a remarkable stability of 100 h at 500 mA cm⁻². This can be closely related to the fact that dual doping with low-valence Fe and high-valence Mn in Ni_0.85Se can create electron-rich Se sites to accelerate water dissociation and electron-deficient Ni sites to promote proton recombination simultaneously, thereby synergistically lowering the energy barrier and boosting the overall HER activity. The present work offers a universal and guiding strategy to prepare high-performance electrocatalysts with dual doping of low-valence and high-valence metals for industrial-level hydrogen production.