Highly dispersed PdCu nanoparticles for enhanced formic acid oxidation: Ordering effect of intermetallic compound structure

Abstract

Ordered Pd-based intermetallic electrocatalysts have broader application prospects in formic acid oxidation reactions (FAOR) due to their excellent catalytic efficiency and selectivity compared to disordered alloy electrocatalysts. Herein, monodisperse ordered PdCu nanoparticle electrocatalysts were prepared in one pot by liquid phase reduction reaction, which avoided the problems of catalyst aggregation and sintering caused by traditional high temperature calcination method. Compared to disordered PdCu alloy (D-PdCu/C) and commercial Pd/C electrocatalysts, the ordered PdCu intermetallic nanoparticle electrocatalysts (O–PdCu/C) display enhanced catalytic activity and durability in FAOR process. The mass activity of O–PdCu/C for formic acid electrooxidation is 1055 mA mg_Pd⁻¹, which is 2.1 and 4.4 times higher than that of D-PdCu/C and commercial Pd/C, respectively. In the long cycle durability test, O–PdCu/C maintains higher mass activity and good stability than D-PdCu/C electrocatalysts. In-situ Attenuated-Total-Reflection Surface-Enhanced Infrared Absorption Spectroscopy (ATR-SEIRAS) shows that the bridged CO on O–PdCu/C can be easily oxidized and resolved during the reaction process, effectively suppressing the accumulation of CO_ads on O–PdCu/C. The excellent electrocatalytic performance and stability are attributed to the ordered intermetallic nanoparticle structure and the synergistic effect between Pd–Cu electrons of O–PdCu/C, providing a highly cost-effective anode catalyst for direct formic acid fuel cells (DFAFCs). We believe that our research results will contribute to develop low-cost, efficient and stable electrocatalysts, and promote the application and development of ordered Pd-based intermetallic electrocatalysts in DFAFCs.