Laser irradiation synthesized carbon encapsulating ultrafine transition metal nanoparticles for highly efficient oxygen evolution

• Laser irradiation strategy is universal to synthesis carbon shell encapsulated NPs. • As-obtainted FeNiO x @C-CNT displays excellent OER activity compared with RuO 2 catalyst. • FeNiO x @C-CNT shows unfading activity after 20k cycles attributing to carbon shell. Developing efficient electrocatalysts with high activity and stability for oxygen evolution reaction (OER) is of crucial importance. Herein, carbon shell encapsulated ultrafine FeNiO x NPs with an average size of 2.32 nm uniformly dispersing on CNT (denoted as FeNiO x @C-CNT) was synthesized via a simple laser irradiation technique. The as-prepared FeNiO x @C-CNT composites present excellent electrocatalytic OER activity, mainly owing to the small size and high dispersion of FeNiO x NPs. Electrochemical measurement show that these composites possess a low overpotential of 267 mV at 10 mA cm -2 as well as a small tafel slope of 46.29 mV dec -1 . Additionally, encapsulation in the carbon shell effectively preserve the FeNiO x NPs from degrading under the harsh external condition, showing almost unfading electrocatalytic activity after 20000 potential cycles. Importantly, this strategy is universal and could be extended to synthesis other type of carbon shell encapsulated metal-based material (e.g. FeO x @C-CNT, CoO x @C-CNT, NiO x @C-CNT and MnO x @C-CNT), which might provide a new way to design high-efficiency electrocatalysts.