New 3-D Mn(II) Coordination Polymer with Redox Active Oxalate Linker; an Efficient and Robust Electrocatalyst for Oxygen Evolution Reaction

A novel three dimensional coordination polymer {[Mn(ox)(3/2)][bap]center dot(H2O)}(n), (1) (ox = oxalate, bap = N-benzyl-4-aminopyridinium) is reported in this work as an efficient electrocatalyst for oxygen evolution reaction (OER). 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) based dispersion condition as well as interactions between the adjacent layers of anionic coordination polymer and N-benzyl-4-aminopyridinium were found necessary for the growth and stability of this architecture. Single crystal XRD, IR and elemental analysis confirmed the formation of compound (1). Morphology and thermal stability were evaluated by SEM and TG respectively. Electrochemical studies were carried out in a three-electrode system using 1 coated FTO as a working electrode using 0.1 M KOH solution. The electrochemical investigation showed that 1 produced a current density of 10 mAcm(-2) at a relatively low overpotential (eta = 404 mV) while a maximum current density of 62 mAcm(-2) was achieved. A catalytic onset potential for OER was observed at 1.5 V (vs RHE) and needed overpotential of 258 mV. The catalyst offered a turnover frequency (TOF) of 0.06 s(-1) for OER at 404 mV. Long-term stability measurements of 1 were recorded by using chronoamperometry, IR analysis and LS voltammograms for the pristine and post-catalytic 1 coated FTO electrodes that confirmed the durability of the catalyst. The fascinating electrochemical behaviour of 1 toward oxygen evolution reaction can be attributed to its 3D polymeric structure and represents 1 as a robust and efficient catalyst towards OER.