Three-dimensional Composite Catalysts for Al-O 2 Batteries Composed of CoMn 2 O 4 Nanoneedles Supported on Nitrogen-Doped Carbon Nanotubes/Graphene.

Great efforts have been focused on studying high-efficiency and stable catalysts towards oxygen reduction reaction (ORR) in metal-air batteries. In view of synergistic effects and improved properties, carbon nanotubes and three-dimensional graphene (CNTs-3D graphene) hybrid catalysts developed via a well-controlled route is urgently required. Herein, a CoMn2O4 (CMO) nanoneedles supported nitrogen-doped carbon nanotubes/3D graphene (NCNTs/3D graphene) composite was prepared by in-situ chemical vapor deposition (CVD) along with hydrothermal methods over a Ni foam substrate. The cyclic voltammetry (CV) and linear sweep voltammograms (LSVs) results indicate that the CMO/NCNTs/3D graphene hybrid possesses remarkable electrocatalytic performance towards ORR in alkaline condition compared with NCNTs/3D graphene, CMO/3D graphene, and 3D graphene catalysts, even outperforming the commercial 20 wt.% Pt/C catalyst. Moreover, the Al-air coin cell employing CMO/NCNTs/3D graphene as cathode catalysts obtains an open circuit voltage of 1.55 V and a specific capacity of 312.8 mAh g-1, which are superior to the Al-air coin cell with NCNTs/3D graphene as catalysts. This work supplies new insights to advanced electrocatalysts introducing NCNTs/3D graphene as a catalyst support to develop scalable transition metal oxide/NCNTs/3D graphene hybrids with excellent catalytic activity towards ORR in Al-air systems.