MOF-Derived Mn2 O3 Nanocage with Oxygen Vacancies as Efficient Cathode Catalysts for Li-O2 Batteries.

ABSTRACT

Designing efficient and cost-effective electrocatalysts is the primary imperative for addressing the pivotal concerns confronting lithium-oxygen batteries (LOBs). The microstructure of the catalyst is one of the key factors that influence the catalytic performance. This study proceeds to the advantage of metal-organic frameworks (MOFs) derivatives by annealing manganese 1,2,3-triazolate (MET-2) at different temperatures to optimize Mn2 O3 crystals for special microstructures. It is found that at 350 °C annealing temperature, the derived Mn2 O3 nanocage maintains the structure of MOF, the inherited high porosity and large specific surface area provide more channels for Li+ and O2 diffusion, beside the oxygen vacancies on the surface of Mn2 O3 nanocages enhance the electrocatalytic activity. With the synergy of unique structure and rich oxygen vacancies, the Mn2 O3 nanocage exhibits ultrahigh discharge capacity (21 070.6 mAh g-1 at 500 mA g-1 ) and excellent cycling stability (180 cycles at the limited capacity of 600 mAh g-1 with a current of 500 mA g-1 ). This study demonstrates that the Mn2 O3 nanocage structure containing oxygen vacancies can significantly enhance catalytic performance for LOBs, which provide a simple method for structurally designed transition metal oxide electrocatalysts.