A Redox-Active 1D Co(II) Coordination Polymer and Its Ni-Composite: Structure, Surface Characterization, and Application in the Water Splitting Reaction

Energy is at the heart of a sustainable society; with
increasing
focus on noncarbon (non-C) energy sources, hydrogen (H2) fuel is the center of attraction as a clean alternative. Among
emerging technologies, electrocatalytic water splitting, especially
the oxygen evolution reaction (OER), plays a crucial role in sustainable
H2 production. In line with Sustainable Development Goals
(SDGs), coordination polymers (CPs) have attracted consideration due
to their flexible porosity, high surface area, redox-active metal
centers, and structural stability, making them promising OER catalysts.
Herein, we report a redox-active Co(II)-based coordination polymer
(Co-CP), synthesized using the unsymmetrical bridging ligand (E)-N-(pyridin-4-ylmethylene)-4H-1,2,4-triazol-4-amine
(pmta) and terminal carboxylate ligand 2,5-thiophenedicarboxylate
(tda2–). The
Co-CP exhibits electrocatalytic OER activity in an alkaline medium.
To check the performance of OER activity, Ni2+ has been
incorporated into the Co-CP framework, to form Ni@Co-CP composites.
Optimized OER efficiency is observed for Ni-2@Co-CP, which shows stability
of the crystalline framework upon nickel incorporation even under
strenuous experimental conditions and exhibits an overpotential of
290 mV at 10 mA cm–2, a Tafel slope of 35 mV dec–1, and a charge transfer resistance of 6.97 Ω.
The strategic incorporation of extraneous metal ions into CP frameworks
offers a versatile approach for designing advanced electrocatalysts.
Such materials not only show great promise for OER but also hold potential
for broader energy conversion and storage applications.