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

The surface reconstruction of MnO 2 nanorods was strategically carried out by thermal decomposition of the Ni[MPDTC] 2 complex to form a MnS-MnO-Ni 3 S 2 /Ni 0 (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 MnO 2 and Ni 9 S 8 . 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 MnO 2 and Ni 9 S 8 under a wide range of pH. The MNS catalyst produces 629.4 μmol h –1 of H 2 with an energy efficiency of 52.66 kWh kg –1 of H 2 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.