Metal-Complex-Assisted Surface Reconstruction of MnO ₂ Nanorods for the Hydrogen Evolution Reaction under a Wide pH Range

The surface reconstruction of MnO2 nanorods was strategically carried out by thermal decomposition of the Ni[MPDTC]2 complex to form a MnS-MnO-Ni3S2/Ni0 (MNS) composite nanostructured material. MNS exhibited enhanced hydrogen evolution reaction (HER) performance under acidic, neutral, and alkaline media, with a lower overpotential and superior durability. MNS exhibited an overpotential of 187 and 258 mV to produce a current density of 10 mA cm–2 in acidic and alkaline media, respectively, which are significantly lower than those of the pure MnO2 and Ni9S8. The improved intrinsic HER activity of the MNS arises from interfacial electronic modulation in the composite material. Notably, the Faradaic efficiency of MNS was calculated to be 98.5% and 97.8% in acidic and alkaline media, respectively. The surface reconstruction creates a high density of catalytically active sites and facilitates accelerated interfacial charge transfer, synergistically resulting in reduced overpotentials and lower Tafel slopes compared with pristine MnO2 and Ni9S8 under a wide range of pH. The MNS catalyst produces 629.4 μmol h–1 of H2 with an energy efficiency of 52.66 kWh kg–1 of H2 in a single stack electrolyzer system in alkaline medium. This work presents an innovative and feasible strategy for constructing an efficient electrocatalyst for hydrogen production.