Insights into the enhancement of oxygen evolution catalysis in Ce-mediated amorphous CoFe-based (oxy)hydroxides

Heteroatom doping and nanostructure engineering are recognized as pivotal strategies for enhancing the oxygen evolution reaction (OER) performance of layered double hydroxides (LDHs) and (oxy)hydroxides. However, the reason for performance improvement remains controversial. Herein, we report Ce-incorporated amorphous CoFe-(oxy)hydroxide nanoparticles on nickel foam (NF) via a one-step electrodeposition method, achieving excellent OER activity with a low overpotential (η = 0.220 V at 10 mA cm^-2 in 1.0 M KOH), ranking among the top-performing CoFe-based OER catalysts. Intriguingly, despite the fact that Ce incorporation can reduce the overpotential of CoFe-(oxy)hydroxide, the intrinsic activity and the reaction kinetics are suppressed through Ce incorporation. Instead, the enhancement of OER activity primarily stems from the small particle size and the fast charge transfer. Ce incorporation suppresses the particle coalescence during synthesis, thereby increasing the electrochemically active surface area. In addition, Ce incorporation modulates the interfacial charge-transfer resistance effectively. This work highlights a method for designing high-performance OER catalysts through morphological engineering and electric conductivity modulation.