Mn2O3 Hollow Nanotube Arrays on Ni Foam as Efficient Supercapacitors and Electrocatalysts for Oxygen Evolution Reaction

It is imperative to study the earth abundant nonprecious metal oxides with high electrocatalytic activity and excellent energy storage performance. Herein, Mn2O3 nanotube arrays (Mn2O3 NAs) have been synthesized by controllably annealing the Mn-MOFs precursors. The hollow Mn2O3 NAs exhibit high electrocatalytic activity for oxygen evolution reaction (OER), accompanied by a low overpotential of 270 mV to achieve 10 mA cm–2 in 1.0 M KOH solution. The corresponding Tafel slope is only 85 mV dec–1 and the Faradaic efficiency is nearly 100%. Besides the excellent OER performance, Mn2O3 NAs also exhibit enhanced specific capacitance of 677 F g–1 at 1 mA cm–2, which is preferable to most Mn2O3 materials. The electrocatalytic results strongly demonstrate that the three-dimensional skeleton structure and microstructure of hollow nanotube arrays in Mn2O3 NAs are the intrinsical factors for the enhanced OER performance and high specific capacitance.