摘要
While Palladium (Pd) holds promise as a viable alternative to Platinum (Pt) for oxygen reduction reaction (ORR), a slight performance gap persists. This study strives to fill that gap by generating additional reaction sites on Pd nanoparticles via Sn-oxide (SnOx) surface modifiers (denoted as PdSn) and atomic Sn metal clusters for oxygen reduction reaction (ORR). As developed PdSn electrocatalyst with 1 wt% of surface decorated Sn (denoted as PdSn-1) demonstrates a remarkable improvement of the kinetic current density respectively by 6.34 and 6.74 mA cm−2 as compared to that of its monometallic counterpart (Pd-AC) and the commercial J.M.-Pt/C catalyst in oxygen reduction reaction (ORR) with alkaline solution (0.1 M KOH). It corresponds to an exceptional mass activity of 8150 mA mgSn−1 at 0.85 VRHE and a more than doubled reaction kinetics of ORR in the Pd reaction sites (199 mA mgPd−1). More importantly, the Sn-oxide surface modifiers endow the PdSn-1 electrocatalyst with high durability over 5000 potential cycles in an accelerated degradation test (ADT). The results of the electrochemical analysis reveal that the high ORR performance of PdSn-1 originates from the presence of atomic-scaled SnOx and metallic Sn dimers/trimers on the Pd surface. These reaction sites offer adsorption sites for O2 molecules and trigger the hydroxide ions relocation during ORR. On the other hand, a sharp fall in the ORR performance is observed when the Sn-content is raised to 3 wt% (PdSn-3) and can be attributed to the absence of the local synergetic collaboration of heteroatomic sites to the Pd atoms.
[Display omitted]
•ORR performance of Pd NPs has been enhanced.•Additional reaction sites have been generated on Pd NPs.•Sn-oxide surface modifiers endow the Pd NPs with high durability.