Cable Bacteria-Inspired Hemin-Nickel Coordination Polymers with Carbon Nanotubes for Enhanced Oxygen Evolution

In recent years, coordination polymers have attracted significant attention as promising hybrid materials for electrochemical energy conversion due to their conductivity, large surface area, and tunable chemical composition. In this study, inspired by the conductive filaments of cable bacteria, poly(nickel tetrathiooxalate) was non-covalently modified with hemin and composited with multi-walled carbon nanotubes using a simple synthesis method. The synthesized electrocatalyst demonstrated excellent oxygen evolution reaction activity and stability in alkaline freshwater, requiring low overpotentials of 270 and 317 mV to achieve current densities of 10 and 50 mA cm⁻², respectively, with a small Tafel slope of 71 mV dec⁻¹. Moreover, it maintained continuous stability for 72 hours at current density of 10 mA cm⁻², highlighting its long-term durability. Our study also investigates the electrochemical properties of the synthesized electrocatalyst for alkaline seawater OER, demonstrating sustained activity despite challenges from electrode corrosion and chloride ion oxidation at the anode. Thus, this study offers valuable insights into the design of advanced electrocatalysts for OER within this class of materials.