Controllable oxidation protocol for the synthesis of amorphous NiO-Modified oxidation graphene-coated Ni nanoparticles toward highly efficient and stable alkaline water splitting.

Although nanoscale Ni-based materials possess exceptional theoretical hydrogen evolution reaction (HER) activity, their synthesis and long-term storage stability remain critical barriers to practical applications. In this study, we propose a controlled oxidation strategy to synthesize amorphous NiO-modified oxidation graphene-encapsulated Ni nanoparticles (Ni@GO) as highly efficient and durable electrocatalysts for alkaline water electrolysis. This strategy integrates a self-assembly confinement effect with a calcination process to fabricate ultrasmall Ni nanocrystals, followed by passivation oxidation to in situ generate a non-uniform amorphous NiO layer on the Ni surface. This approach not only prevents the spontaneous combustion of nanoparticles, thereby significantly enhancing their storage and application stability, but also constructs a locally optimized Ni/Ni synergistic catalytic interface, effectively modulating and balancing the Volmer and Heyrovsky/Tafel reaction pathways, and greatly boosting alkaline HER performance. The synthesized Ni@GO catalyst exhibits an ultra-low overpotential of 60 mV at 10 mA cm in 1 M KOH, as measured on a GCE electrode. Furthermore, it demonstrates an overall water-splitting activity comparable to that of commercial Pt/C and RuO catalysts. Notably, after being stored in ambient air for over 1.5 years, the catalyst retains its excellent electrocatalytic performance. This study presents an efficient, stable, and scalable strategy, providing valuable insights for the design and application of low-cost, high-performance electrocatalysts.