Ternary PdNiO nanocrystals-ornamented porous CeO 2 /onion-like carbon for electrooxidation of carbon monoxide: unveiling the effect of supports and electrolytes

Porous ternary Pd-based catalysts are highly promising for various electrocatalytic applications, due to their low Pd mass, high surface area, accessible active sites, and tunable electronic structure; however, their activity for CO oxidation (CO oxid ) in different electrolytes is yet to be reported. Herein, ternary PdNiO nanocrystals supported on porous CeO 2 /onion-like carbon nanostructures (PdNiO–CeO 2 /OLC) were prepared by the sol–gel and impregnation approaches for electrochemical CO oxid in different electrolytes at room temperature. Notably, porous CeO 2 /OLC acts as a support and nanoreactor for supporting the growth of PdNiO without the need for reducing agents or surfactants. The as-obtained PdNiO–CeO 2 /OLC had a porous sponge-like structure composed of ultra-small PdNiO nanocrystals (8 ± 1 nm) distributed on porous flower-like CeO 2 and OLC, which possessed unique merits of multifunctional structure, clean surface, low mass of Pd (10 wt%), porosity (0.30 cm 3 g −1 ), and high surface area (155.66 m 2 g −1 ). The CO oxid activity of PdNiO–CeO 2 /OLC was higher than those of PdNiO/OLC, PdNiO–CeO 2 , and commercial Pd/C catalyst, owing to the electronic interaction of PdNiO with CeO 2 /OLC support, which eases CO adsorption/activation alongside activation/dissociation of H 2 O to generate active oxygenated species ( i.e. , OH) needed for accelerating CO oxid kinetics. The CO oxid activity of PdNiO–CeO 2 /OLC in acidic electrolyte (HClO 4 ) was better than those in alkaline (KOH) and neutral (NaHCO 3 ) electrolytes. This study may open new doorways for understanding the effect of electrolytes and supports on the CO oxid activity of porous ternary Pd-based catalysts.