Influence of the Carboxylates in the 3D Pb(II) Based Catalysts on the Electrochemical Oxygen Evolution Reaction

The Oxygen Evolution Reaction (OER) is considered to be one of the most important processes for energy storage and conversion applications. However, due to its sluggish kinetics it becomes extremely crucial to design and develop cost-effective, stable and highly efficient electrocatalysts. Herein, we report two lead(II) based coordination polymers (CPs) {[Pb₂(TPBN)(TDC)₂].3H₂O}_n (CP1), and {[Pb₂(TPBN)(FDC)₂].H₂O}_n (CP2) synthesized via self-assembly at ambient conditions in good yields (where TPBN= N,N',N''',N''''-tetrakis-(2-pyridylmethyl)-1,4-diaminobutane, H₂TDC=2,5-2,5-thiophenedicarboxylic acid, and H₂FDC=2,5-furandicarboxylic acid. Their 3D structures were determined by Single-crystal X-ray diffraction (SCXRD) studies. The bulk purity and thermal stability of CP1 and CP2 were studied by powder X-ray diffraction studies and thermogravimetric analysis, respectively. Both the CPs showed remarkable catalytic activity for the OER. With a current density of 15 mA cm^-2, for both CP1 and CP2, overpotentials of 570 mV and 630 mV with tafel slope values of 112 mV dec^-1, and 178 mV dec^-1 respectively for CP1 and CP2 in 1.0 M alkaline (KOH) solution was obtained. It is notable that the difference in their catalytic performance - CP1 is better than CP2, can be attributed to the subtle single heteroatom in the dicarboxylate ring (S in thiophene and O in furan, respectively).