Engineering Mesopores and Unsaturated Coordination
in Metal–Organic Frameworks for Enhanced Oxygen Reduction and
Oxygen Evolution Activity and Li–Air Battery Capacity
posted on 2021-03-18, 15:05authored byHao Wang, Fengxiang Yin, Ning Liu, Haiyan Yu, Tianyu Fan, Biaohua Chen
Metal–organic
frameworks (MOFs) have undergone a rapid research
expansion as unpyrolyzed oxygen electrocatalysts due to their flexible
and variable compositions and structures. However, the most studied
MOFs possess microporous nature, which limits the mass-transfer properties
and reduce the space to store insoluble discharge product of aprotic
metal–air batteries. We herein report a partial ligand removal
approach to create mesopore defects and unsaturated coordination in
primarily microporous Cu-BTC (BTC = 1,3,5-bezenetricarboxylic acid).
The mesopores were engineered by introducing isophthalic acid as a
partial ligand, which has one carboxylic group missing compared to
BTC, to construct mesoporous Cu-BTC (MCu-BTC). MCu-BTC was further
loaded by Co species (Co/MCu-BTC) to boost the bifunctional catalytic
performance toward oxygen reduction and oxygen evolution reactions.
The electrochemical characterizations indicate that the mesopores
of MCu-BTC enhanced the discharging capacity (ca. 7000 mAh·g–1) of Co-10/MCu-BTC in an aprotic Li–air battery
owing to the mesopores, which allowed electrolyte infiltration for
both mass and charge transfer and provided more space to store the
discharge product. Further modeling simulations shed light on the
contribution of the unsaturated coordination by significantly promoting
the electronic conductivity and generating adequate interactions with
reactants, leading to enhanced mass- and charge-transfer properties.