Ta-doped cerium oxide electrocatalysts for enhanced oxygen evolution in anion exchange membrane water electrolysis

AbstractCeria (CeO₂) is a promising OER electrocatalyst owing to its facile redox chemistry, oxophilicity, and ability to form oxygen vacancies (O_vs). However, pristine CeO₂ has low electrical conductivity, limiting its catalytic performance. Therefore, defect engineering and electronic–structure modulation are essential strategies. Herein, we propose a simple electrochemical deposition method to fabricate tantalum–doped CeO₂ (Ta−CeO₂), exploiting the multivalent states of tantalum (Ta) to enhance activity for the alkaline OER and anion exchange membrane water electrolysis (AEMWE). Ta incorporation promotes electron transfer from Ta to Ce, generating low–valent Ce3+ species and abundant O_vs, thereby improving electrical conductivity and OER activity. The Ta−CeO₂ catalyst exhibits enhanced reaction kinetics over pristine CeO₂ and IrO₂, as evidenced by a reduced Tafel slope of 65.5 mV dec−1 and a 184 mV overpotential at 10 mA cm−2. A theoretical overpotential decrease from 1.69 V to 1.14 V is predicted by DFT calculations, stemming from a 0.35 eV band gap reduction and optimized adsorption energetics for OER intermediates upon Ta doping. Practical AEMWE tests show that Ta−CeO₂ reaches 1 A cm−2 at 1.72 V and exhibits a 3.49% voltage increment over 100 h, confirming its long−term stability.