Unveiling the electrochemical CO oxidation activity on support-free porous PdM (M = Fe, Co, Ni) foam-like nanocrystals over a wide pH range

Binary PdM-based nanocrystals are efficient electrocatalysts for a wide range of renewable and green fuel cell applications; however, their poisoning by CO is a great barrier for commercialization, so it is pivotal to solve this issue. Herein, we fabricated support-free PdM alloys (M = Fe, Co, and Ni) by a prompt one-step aqueous-solution co-reduction with sodium borohydride driven by the coalescence growth mechanism. This forms support-free PdM porous foam-like nanostructures with well-defined compositions from the ICP-OES analysis and clean surface without any hazardous chemicals or multiple reaction steps. The as-prepared PdM foam-like nanostructures were demonstrated for carbon monoxide oxidation (CO_Oxid) electrocatalysis at varied electrolyte pH compared with commercial Pd/C catalyst. The foam-like PdFe nanocrystals achieved an excellent electrochemical CO_Oxid activity that was at least 2.18-times of PdCo, 4.35-times of PdNi, and 1.56-times of Pd/C in both alkaline (KOH) and acidic (HClO₄) electrolytes, but PdCo was the best in neutral (NaHCO₃) medium. The superior activity of PdM is due to the strain and alloying effect, which promoted the superb CO oxidation durability for 1000 cycles than Pd/C catalyst. This study demonstrated the superiority of support-free bimetallic PdM alloys than Pd/C catalyst in all electrolytes, which may open new gates for understanding CO-poisoning in alcohol-based fuel cells.

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Published in: Energy Conversion and Management: X
License: http://creativecommons.org/licenses/by/4.0/
See article on publisher's website: https://dx.doi.org/10.1016/j.ecmx.2023.100449