Ru-Etched CuCoO₂ Nanocrystals Used as an Efficient Electrocatalyst for the Oxygen Evolution Reaction

Electrocatalytic water electrolysis is intrinsically limited by the slow kinetics of the oxygen evolution reaction (OER) at the anodic electrode. The development of highly active and stable catalysts for the OER is both essential and challenging. In this work, we employed porous metal-organic frameworks (MOFs) to synthesize Ru-etched MOF-derived CuCoO₂ nanocrystals used as an OER catalyst. The electrochemical test results revealed that the Ru-etched CuCoO₂ electrode (Ni@CCORu-3) synthesized via a 3 h RuCl₃-etching reaction exhibits superior catalytic activity (η₁₀ = 368.4 mV, Tafel slope = 81.2 mV dec^-1) in 1.0 M KOH electrolyte. After an 18 h OER stability test, the Ni@CCORu-3 exhibited excellent stability with a minimal overpotential degradation of approximately 30 mV. This enhancement in OER activity can be attributed to the improved specific surface area and pore structure of the MOF-derived CCORu-3 catalyst, resulting from RuCl₃ etching. Furthermore, the electron distribution on the catalyst surface is modulated by Ru species loaded onto the surface. X-Ray photoelectron spectroscopy (XPS) and ultraviolet-visible-near infrared (UV-Vis-NIR) absorption spectra results revealed that RuCl₃ etching increases the proportion of active sites and narrows the bandgap of CuCoO₂, thereby accelerating electron transfer rates during the OER process and optimizing catalytic activity. This study may provide a novel insight into enhancing the OER performance of CuCoO₂ catalysts derived from MOFs.