Quasi-zero-dimensional cobalt-doped CeO2 dots on Pd catalysts for alcohol electro-oxidation with enhanced poisoning-tolerance

Abstract

Deactivation of an anode catalyst resulting from the poisoning of CO_ad-like intermediates is one of the major problems for methanol and ethanol electro-oxidation reactions (MOR & EOR), and remains a grand challenge towards achieving high performance for direct alcohol fuel cells (DAFCs). Herein, we report a new approach for the preparation of ultrafine cobalt-doped CeO₂ dots (Co-CeO₂, d = 3.6 nm), which can be an effective anti-poisoning promoter for Pd catalysts towards MOR and EOR in alkaline media. Compared to Pd/CeO₂ and pure Pd, the hybrid Pd/Co-CeO₂ nanocomposite catalyst exhibited a much enhanced activity and remarkable anti-poisoning ability for both MOR and EOR. The nanocomposite catalyst showed much higher mass activity (4×) than a state-of-the-art PtRu catalyst. The promotional mechanism was elucidated using extensive characterization and density-functional theory (DFT). A bifunctional effect of the Co-CeO₂ dots was discovered to be due to (i) an enhanced electronic interaction between Co-CeO₂ and Pd dots and (ii) the increased oxygen storage capacity of Co-CeO₂ dots to facilitate the oxidation of CO_ad. Therefore, the Pd/Co-CeO₂ nanocomposite appears to be a promising catalyst for advanced DAFCs with low cost and high performance.