Co3O4@3D ordered macro-/mesoporous TiO2 as an excellent cathode catalyst for rechargeable Li–O2 batteries

Abstract

Developing efficient bifunctional electrocatalysts with low cost for oxygen reduction and evolution (ORR and OER) is desirable and remains challenges for lithium-oxygen batteries (LOBs). Here, we report an advanced composite catalyst based on 3D ordered macro-/mesoporous TiO 2 embedded with Co 3 O 4 nanoparticles (Co 3 O 4 @3DOM-TiO 2 ) by in situ embedding Co 3 O 4 nanoparticles (Co 3 O 4 NPs) in TiO 2 framework. The as-prepared Co 3 O 4 @3DOM-TiO 2 possesses hierarchically porous structure combined with interconnected macropores and mesopores on TiO 2 skeleton, ultrafine Co 3 O 4 NPs embedded in TiO 2 walls, and high BET surface area (83.2 m 2 g −1 ). The Co 3 O 4 @3DOM-TiO 2 oxygen electrode delivers a higher full discharge specific capacity of 7635.9 mAh g −1 at 100 mA g −1 , better rate capability and cycling durability (288 cycles at 200 mA g −1 ) compared with bare Co 3 O 4 NPs and Co 3 O 4 NPs supported on 3DOM-TiO 2 (Co 3 O 4 /3DOM-TiO 2 ). Such excellent catalytic performances are mainly due to the synergistic effects among the various components in Co 3 O 4 @3DOM-TiO 2 , including 3D ordered macropores that is in favor of rapid diffusion for reactants and ions, uniformly dispersed Co 3 O 4 NPs providing rich active sites, and mesopores that further facilitates the accessible of reactant to active sites. Furthermore, TiO 2 skeleton with Co 3 O 4 NPs embedded in can facilitate the cycling stability because the embedded Co 3 O 4 NPs are not easy to fall off from the TiO 2 framework to cause capacity loss. Co 3 O 4 @3D ordered macro-/mesoporous TiO 2 is prepared by a facile template strategy and this catalyst exhibits superior electrochemical performance in Li–O 2 batteries. • Co 3 O 4 @3D ordered macro-/mesoporous TiO 2 is prepared. • Small Co 3 O 4 nanoparticles are uniformly embedded in macroporous walls of TiO 2 . • Co 3 O 4 @3DOM-TiO 2 exhibits great performance as oxygen electrode for Li–O 2 batteries.