Enhanced oxygen evolution reaction through Gd doping-enabled manipulation of oxygen coupling pathway in CoFe oxyhydroxide

Developing efficient catalysts for electrochemical oxygen evolution is critical for advancing water electrolysis systems. CoFebased oxyhydroxides have long been recognized as promising materials for the oxygen evolution reaction (OER). However, traditional oxygen coupling mechanisms, specifically the adsorbate evolution mechanism (AEM) or the lattice oxygen mechanism (LOM), suffered from either low activity or stability. In this study, we demonstrate that doping CoFe oxyhydroxides with Gd effectively alters the oxygen coupling pathway. Using in situ differential electrochemical mass spectrometry (DEMS), attenuated total reflectance infrared spectroscopy (ATR-IR), and electrochemical kinetic analyses, we reveal that Gd doping shifts the pathway from AEM and LOM to the more efficient oxide path mechanism (OPM). Density functional theory (DFT) analysis indicates that this shift is related to the optimized adsorption energy of OH at neighboring Co-Fe sites and a reduced Co-Fe distance due to Gd doping. Consequently, the CoFeGdO catalyst exhibits remarkable OER performance, achieving a reduced overpotential of 37 mV at the current density of 10 mA cm^-2, along with excellent stability over 100 h at a constant current density of 100 mA cm^-2. This study highlights a promising strategy for enhancing oxygen evolution performance via oxygen coupling pathway manipulation.