Ni@Ru core-shell nanoparticles on flower-like carbon nanosheets for hydrogen evolution reaction at All-pH values, oxygen evolution reaction and overall water splitting in alkaline solution

Developing highly active, stable, and efficient electrocatalysts for overall water splitting (OWS) is imperative to produce hydrogen with high purity. Herein, a series of Ni@Ru core-shell nanoparticles on flower-like carbon nanosheets (denoted as Ni@Ru/CNS-x, where x is the initial Ru mass loading percentage, and x = 5%, 10%, 15%) were fabricated through a facile wet chemical strategy by employing a metal-organic framework (MOF) as a sacrificial precursor. The Ni@Ru/CNS-x series was investigated to catalyze hydrogen evolution reaction (HER) in all-pH-value solutions, oxygen evolution reaction (OER) and water electrolysis in alkaline media. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) analysis revealed the Ni@Ru/CNS-x presented a three-dimensional (3D) flower-like structure composed of nanosheets with a thickness of approximately 30 nm. The resultant catalysts exhibited excellent HER, OER and OWS performance in 1.0 M KOH. Ni@Ru/CNS-10% displayed the most outstanding electrocatalytic properties , evidenced by a low overpotential of 20.1 mV and 356 mV @ 10 mA cm −2 for HER and OER in 1.0 M KOH, and outperformed stability than Pt/C and RuO 2 for HER and OER, respectively. Moreover, it exhibited a potential of 1.612 V @10 mA cm −2 in the practical OWS test, superior to both Pt/C and RuO 2 catalysts. The strategy can be extended for rational design and preparation of low cost, highly active and durable electrocatalyst with bifunctionalities for OWS and other renewable energy devices.