Hydrogen Intercalation-Induced Crystallization of Ternary PdNiP Alloy Nanoparticles For Direct Formic Acid Fuel Cells

Direct formic acid fuel cells (DFAFCs) are among the promising energy sources in the future low-carbon economy. A key challenge hindering their scale-up and commercialization is the lack of efficient electrocatalysts for anodic formic acid oxidation (FAO). Very recently, the FAO performance of palladium hydrides (PdHx) has been found to be superior to the pristine Pd that is well known for its high intrinsic FAO activity. However, there is enormous space for the controlled synthesis and electrocatalytic behaviors of PdHx-based nanomaterials awaiting to be explored. Herein, the hydrogen intercalation-induced crystallization of PdNiP alloy nanoparticles is reported, and the obtained PdNiP-H nanoparticles exhibit excellent FAO performance. Of particular note, the FAO stability of PdNiP-H is much better than that of pristine Pd-H. Furthermore, the PdNiP-H nanoparticles are used as the anode catalyst in a prototype DFAFC, which demonstrate much higher power density than commercial Pd/C. Density functional theory calculations show that the synergistic effect of alloying Ni and P endows the PdNiP-H with a higher preference toward FAO via the direct pathway and better anti-CO* poisoning capability. This work shines new light on the development of PdHx-based nanoalloys with good activity and stability for DFAFC applications.