La2O3-NCNTs hybrids in-situ derived from LaNi0.9Fe0.1O3-C composites as novel robust bifunctional oxygen electrocatalysts

A robust bifunctional electrocatalyst for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is highly desired for the application in rechargeable metal air batteries. Here, we report a new strategy to in-situ prepare La2O3-nitrogen doped carbon tubes (NCNTs) hybrids by one step calcination treatment with LaNi0.9Fe0.1O3 perovskite oxides as precursors, sugar as carbon sources and urea as nitrogen sources. The contents of applied LaNi0.9Fe0.1O3 oxides affect the formation of NCNTs, and the obtained NCNTs have abundant wrinkles on the surface. In alkaline solution, the LO-NF-NCNTs-1.0 sample catalyzes the ORR with an onset potential of 0.896 V (vs. RHE) and a half-wave potential (E-1/2) of 0.772 V (vs. RHE), which is only an E-1/2 gap of 65 mV compared with commercial Pt/C catalyst. Meanwhile, the LO-NF-NCNTs-1.0 sample exhibits better OER activities than the commercial RuO2 catalyst. Significantly, we demonstrate that the LO-NF-NCNTs-1.0 sample possesses surprisingly catalytic stabilities, and an outstanding tolerance towards methanol crossover. The excellent bifunctional activities may be attributed to the typical morphology of NCNTs, coupling effect between NCNTs and La2O3 because of the formation of active La-O and C-O bonds. (C) 2017 Elsevier Ltd. All rights reserved.