The controlled synthesis of PdAg alloy nanospheres and the selective oxidation of ethylene glycol

Abstract

The application of direct ethylene glycol fuel cells (DEGFCs) faces challenges such as sluggish anode reaction rates and incomplete ethylene glycol oxidation. To tackle these issues, we adopted a straightforward chemical reduction approach for the synthesis of sea urchin-like PdAg nanospheres (PdAg NSs). Concurrently, we investigated the influence of varying Pd/Ag molar ratios on the ethylene glycol oxidation reaction (EGOR). Our results demonstrate that sea urchin-like nanospheres with distinct morphological features can be successfully synthesized with different Pd/Ag ratio combinations. Electrochemical analyses reveal that the rational design of bimetallic catalysts can enhance catalytic activity, which is primarily attributed to the ligand effect. Notably, Pd₄Ag NSs exhibit the highest mass activity of 5.98 A mg_Pd⁻¹, significantly outperforming commercial Pd/C catalysts. Moreover, Pd₄Ag NSs also demonstrate superior electrochemical stability in both chronoamperometry (CA) and cyclic voltammetry (CV) tests. In addition, the faradaic efficiency (FE) of the cleavage products was evaluated. A volcano-type relationship was observed between the FE of cleavage products and the applied potential. The results indicate that 0.96 V vs. RHE is the optimal potential for the formation of cleavage products, at which the corresponding FE reaches 15%. This study not only provides insights into the synthesis of high-stability Pd-based nanomaterials but also reveals the relationship between potential and oxidation products in the ethylene glycol oxidation reaction (EGOR).