Enhancing CoFe Catalysts with V2CTX MXene-Derived Materials for Anion Exchange Membrane Electrolyzers

Herein, the synthesis and characterization of Co0.66Fe0.34 layered double hydroxides (LDH) derived from pure and vacancy-engineered V2CTx MXenes and their use as electrocatalysts for the oxygen evolution reaction (OER) is reported. Two distinct MXene materials are investigated: pristine V2CTx and V1.8CTx containing 10% vanadium vacancies. Through systematic variation of the MXene content (17–75 wt.%), it demonstrates that the utilization of MXenes significantly enhances OER activity compared to pure Co0.66Fe0.34. The vacancy-engineered composite Co0.66Fe0.34@V1.8CTx achieved superior performance with an overpotential of 304 mV at 10 mA cm−2 (CFVv75), compared to 317 mV for the best-performing V2CTx MXene composite (CFV33). In situ X-Ray absorption spectroscopy revealed the formation of highly oxidized Co (i.e., Co(III) and Co(IV)) species during OER, while also indicating irreversible oxidation of vanadium to V(V). Despite partial vanadium leaching, both materials demonstrated excellent stability over 12 h of operation at 100 mA cm−2. Notably, CFVv75 showed superior initial performance under practical anion exchange membrane electrolyzer conditions, operating at cell voltages of 100 mV lower than the pure Co0.66Fe0.34. This work demonstrates the potential of vacancy engineering and materials discovery using MXene materials for enhancing electrocatalytic performance and provides insights into the dynamic evolution of these materials under operating conditions.