Samarium-based metal organic frameworks as high performance electrocatalyst for alkaline water splitting

Due to ever-increasing energy demand, development of inexpensive and highly active metal-based materials such as metal-organic framework (MOF) nanoarchitectures for efficient electrocatalytic water splitting via oxygen evolution reactions (OER) and hydrogen evolution reactions (HER) has become a highly challenging task in recent years. Herein, we synthesized two different MOFs by hydrothermal method using 1,4-benzene dicarboxylic acid (1,4-BDC) and 2-amino-1,4-benzenedicarboxylic acid (2-NH2-1,4-BDC) as ligands and samarium (Sm) as the metal center. These samarium-based MOF (Sm-MOF) and amine-functionalized samarium-based MOF (NH2 functionalized Sm-MOF) worked as multifunctional catalysts for OER and HER owing to their attractive rod and hollow spherical morphology with visible pores. Among both, NH2 functionalized Sm-MOF exhibited significant HER/OER performance with low overpotential of 20.9/433 mV at 10/10 mA/cm2 and a small Tafel slope of 198/95.1 mV/dec in 1 M KOH electrolyte respectively. Moreover, its stability is maintained with 1000 cycles with a minute shift in performance. This strategy shows the novel approach to design a bifunctional electrocatalyst with improved electrochemical surface area (ECSA) of 5650/7425 cm2 for HER/OER and more efficiency for overall electrocatalytic water splitting under alkaline conditions.