Intermetallic Pd3Pb Nanoplates Enhance Oxygen Reduction Catalysis with Excellent Methanol Tolerance

Herein, a new class of intermetallic Pd3Pb square nanoplates (SNP) and nanoplates assemblies is demonstrated with tunable crystalline orientation for boosting oxygen reduction reaction (ORR) activity and stability with excellent methanol tolerance. The Pd3Pb intermetallic nanostructures show the crystalline-orientation-dependent electrocatalytic activity for ORR with (100)-facet-dominated Pd3Pb SNP being the most active. The Pd3Pb intermetallic SNP exhibits the highest ORR mass activity of 0.78 A mg(-1) at 0.9 V versus reversible hydrogen electrode in alkaline electrolyte for the state-of-art reported Pd-based nanocatalysts, 7.1 times higher than that of commercial Pt/C. The unique structure of Pd3Pb intermetallic SNP makes it highly stable for ORR with almost no activity decrease and no composition and morphology changes after a 5000-cycle durability test. The Pd3Pb intermetallic SNP also exhibits much higher methanol tolerance behavior than commercial Pt/C and Pd/C during ORR catalysis. Density functional theory calculations reveal that presence of Pb decreases adsorption strength of methanol on Pd3Pb intermetallic SNP. The calculated E-methanol follows the order of Pd3Pb (100) < Pd (111) < Pt (111) with (100)-oriented Pd3Pb SNP having the lowest methanol adsorption energy, thus boosting methanol tolerance performance.