Metal-organic framework-derived defect-enriched bimetallic Cerium/Manganese oxide nanocomposite with carbon for boosted water electrolysis and supercapacitor applications

Innovatively regulating the long-term electrochemistry in supercapacitors and electrochemical water-splitting devices has driven the development of proper structural design and composition of low-cost active electrodes. In this work, we synthesized Ce/Mn-MOF and its nanocomposite functionalized with carbon (Ce/Mn-O@C) via a solvothermal method. There is an actual tuning of electronic properties in the derived Ce/Mn-O@C composite, which confirms the presence of numerous reactive redox sites, a maximum effective surface area, and a good charge transfer rate, thereby demonstrating superior electrochemical activities. The Ce/Mn-O@C exhibits an extensive specific capacity of 533 Cg⁻¹ at 1 Ag⁻¹ and delivers a high specific energy of 48 Wh Kg⁻¹ at a specific power of 325 W Kg⁻¹ with its excellent durability and capacity maintenance of 89.5 % after 10,000 cycles. For water electrolysis, the Ce/Mn-O@C requires an ultralow overpotential of 187 and 210 mV for the hydrogen and oxygen evolution reactions to drive 10 mA cm⁻² and showed ultra-long durability of 78 and 60 h, respectively. The key aspect that improves the electrochemical behaviour is the coupling of bimetallic material and carbon, resulting in a highly reactive surface area and defective structure, which strengthens the metal-hydroxide bonding and interfacial charge transfer behaviour. Our current findings suggest designing and fabricating more efficient materials for energy conversion and storage applications.