Modulating Metal-Organic Frameworks as Advanced Oxygen Electrocatalysts

Oxygen-related electrocatalysis, including those used for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), play a central role in green-energy related technologies. Rational fabrication of effective oxygen electrocatalysts is crucial for the development of oxygen related energy devices, such as fuel cells and rechargeable metal-air batteries. Recently, owing to their tunable compositions and microstructures, metal-organic frameworks (MOFs) based materials have drawn extensive attention as nonprecious oxygen electrocatalysts. Various strategies have been developed to fabricate MOF-based electrocatalysts and regulate their active sites, such as heterometal doping, defect engineering, morphology tuning, heterostructure construction, and hybridization. In this review, by focusing on various modulation strategies aiming at active sites, the recent advances of MOF-based electrocatalysts are summarized. The synthetic methods used to synthesize various MOF-based oxygen electrocatalysts are discussed, followed by the underlying engineering mechanisms required to allow performance enhancement, and finally some existing challenges that hinder for their practical applications are discussed alongside a perspective on their possible future.