Facile preparation of hierarchical Ni@Mn-doped NiO hybrids for efficient and durable oxygen evolution reaction

Exploring highly efficient and non-noble-metal-based electrocatalysts for oxygen evolution reaction(OER)is of great importance not only for water splitting but also for rechargeable metal-air batteries and fuel cells.Herein,we describe a simple strategy to prepare hierarchical Ni@Mn-doped Ni O hybrids using flower-like Ni-Mn layered double hydroxides(Ni Mn-LDHs)as a precursor.After calcination at 400℃for an hour under N_(2)atmosphere,the flower-like Ni Mn-LDHs transform to porous microspheres consisting of nanoparticles,in which Ni cores are encapsulated by Mn-doped NiO shells(denoted as Ni@MnNi O-400).Benefiting to this unique porous,core-shell structures and element doping,the as-prepared Ni@Mn-NiO-400 hybrid shows a low overpotential of 178 mV at the current density of 10 mA/cm^(2)and Tafel slope of 52.7 m V/dec in 1 mol/L KOH solution.More significantly,the Ni@Mn-Ni O-400 hybrid also demonstrates superior stability of 98.6%after 50 h continuously testing,much higher than pristine Ni MnLDHs and commercial IrO_(2)catalyst.In addition,theoretical simulation shows that Ni core and Mn doping greatly affect the electronic states and electronic structure of Ni O.As a result,Ni@Mn-doped Ni O hybrid possesses an optimal adsorption activity towards oxygen species than Ni O and undoped Ni@Ni O hybrid.Considering the compositional and structural flexibility of LDHs,this work may offer a simple method to prepare other non-noble metal-based electrocatalysts for OER.