Localized Amorphization Engineering in Ultrathin MnRuO_x Nanosheets for Robust Hydrogen Evolution Reaction

Abstract Although ultrathin noble‐metal nanosheets have arisen as promising high‐efficient electrocatalysts, their catalytic behaviors are still far to be satisfied due to lacking of additional active sites on the basal plane of 2D structure. Herein, partially amorphization strategy is adopted to construct localized amorphous area in ultrathin RuO₂ nanosheets by doping Mn. This strategy endows the MnRuO_x catalyst enriched basal plane active sites, channels for mass transfer, amorphous/crystalline interfaces, and thus a superior HER activity. Impressively, the optimal MnRuO_x NSs‐250, which is achieved by annealing at 250 °C, shows excellent HER performance within alkaline condition with a low overpotential of only 31 mV at 10 mA cm⁻² and a small Tafel slope of 46.7 mV dec⁻¹ which is superior to that of commercial Pt/C catalysts. The key role of localized amorphization on the enhanced HER properties of MnRuO_x NSs‐250 is determined by in situ Raman spectroscopy and theoretical calculations. It is found that Mn doping can promote the adsorption/desorption of H₂O, thus inducing the electron redistribution at the amorphous/crystalline interfaces and accelerating the Volmer step in alkaline HER. This work provides a valuable guidance for improving the performance and stability of other electrocatalysts for alkaline HER applications.