A cobalt metal-organic framework (Co-MOF): a bi-functional electro active material for the oxygen evolution and reduction reaction

• Published in: Dalton transactions : an international journal of inorganic chemistry Vol. 48; no. 28; pp. 1557 - 1564
• Main Authors: Tripathy, Rajat K, Samantara, Aneeya K, Behera, J. N
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 16.07.2019
• Subjects: Current density; Durability; Electroactive materials; Electrocatalysis; Electrocatalysts; Energy storage; Environmental effects; Frequency analysis; Fuel cells; Mapping; Metal-organic frameworks; Methanol; Nanoparticles; Noble metals; Oxygen evolution reactions; Oxygen reduction reactions; Ruthenium oxide; Selectivity; Stability tests; Thermogravimetric analysis
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c9dt01730e

The oxygen electrocatalysis, i.e. the oxygen reduction and evolution reactions, is traditionally executed using noble metal and metal oxide-based nanostructures. However, they are associated with many disadvantages such as high cost, lower durability/selectivity and detrimental environmental effects; this motivates researchers to develop new electroactive materials. In this study, we presented the synthesis of a Co-containing metal-organic framework (Co-MOF) and explored its electrocatalytic application towards the oxygen electrocatalysis ( i.e. the oxygen reduction reaction and oxygen evolution reaction). The Co-MOF efficiently catalyzes the ORR with a lower onset (0.85 V vs. RHE)/reduction potential and higher reduction current density by a four-electron reduction path. Moreover, the MOF shows higher durability with >70% performance retention after 25 hours of reaction and tolerance towards methanol; this demonstrates its potential for application in direct methanol fuel cells (DMFCs); furthermore, due to the availability of more active sites and accessible surface area, the Co-MOF performs well towards the OER with lower onset potential and small Tafel slope as compared to the commercial RuO 2 nanoparticles. Moreover, it needs only 280 mV overpotential to deliver the state-of-the-art current density of 10 mA cm −2 and robust stability. It shows the high TOF value of 93.21 s −1 at the overpotential of 350 mV as compared to the reported MOF/nanoparticle-based electrocatalysts and the state-of-the-art RuO 2 . Therefore, we believe that the as-developed Co-MOF holds the potential to be used as both a cathode and an anode electrocatalyst in the future energy storage and conversion systems. Co-MOF catalyzes the ORR efficiently with a lower onset potential (0.85 V vs. RHE) by a four electron reduction path with better durability. It needs only 280 mV overpotential to deliver the state-of-art current density of 10 mA cm −2 .