Regulating the Constituents of 1D Metal Oxalate Chains for Enhanced Electrocatalytic OER Performance

As a new generation of crystalline materials, coordination polymers (CPs) with modular structures have been widely investigated as precatalysts for the oxygen evolution reaction (OER). However, controlling the structural transformation of CPs to form metal oxyhydroxide phases with high catalytic activity remains a challenge. Herein, two similar anionic metal oxalate chains, {[(DEAPA][Co(C₂O₄)₂]}_n (Co-DEAPA) (DEAPA = N,N-diethylpropane-1,3-diaminium) and {[CyNH₃]₂[Co(C₂O₄)₂]·H₂O}_n (Co-CyNH₃) (CyNH₃ = cyclopentylaminium), with different organic ammonium cations, are synthesized. By a simple dissolution-recrystallization method, these two complexes can be easily loaded onto the surface of nickel foam (NF) to form electrodes. The NF-supported Co-CyNH₃ electrode exhibited enhanced OER activity with a lower overpotential of 290 mV compared to the Co-DEAPA counterpart (343 mV) at a current density of 100 mA cm^-2. On this basis, by doping Fe into the Co-CyNH₃ system, a novel NF-supported FeCo-CyNH₃ electrode was constructed and exhibited significantly enhanced OER performance, with the overpotential reduced to 255 mV at 100 mA cm^-2. The CoOOH and FeOOH generated in situ from the CP precursors during the OER electrochemical process serve as active sites for the enhanced OER catalytic activity. This methodology establishes a straightforward approach for constructing high-performance, nonprecious-metal-based electrocatalytic systems.