Platinum praseodymium alloy electrocatalyst for efficient oxygen reduction reaction
Proton exchange membrane fuel cells(PEMFCs)have become a key technology for addressing energy and climate challenges and promoting the hydrogen economy,driven by their high efficiency and zero emissions.However,the sluggish kinetics of the cathodic oxygen reduction reaction(ORR)limit their large-scale application.The design and development of advanced electrocatalysts with high performance and low platinum usage are crucial for improving oxygen adsorption,electron transfer,and mass transport in the cathode three-phase interface region,reducing the kinetic barriers of ORR,and enhancing the efficiency of PEMFCs.Herein,a new paradigm for the development of ORR catalysts with both high activity and stability is presented by leveraging the rare earth element praseodymium(Pr)to modulate platinum(Pt).The unique electronic configuration and lower electronegativity of Pr,when alloyed with Pt,induce a ligand effect that adjusts the microelectronic structure,improving the local electronic configuration of active sites and intrinsic activity.A carbon-supported PtPr binary alloy catalyst(PtPr/C)was successfully synthesized via a simple polyol thermal reduction method.In three-electrode system ORR performance tests,PtPr/C exhibits a half-wave potential of 0.92 V,20 mV higher than Pt/C,with a mass activity four times that of commercial Pt/C.After 10 000 cycles in accelerated durability testing,PtPr/C shows only a 13 mV decrease in half-wave potential,demonstrating superior stability compared to Pt/C.In PEMFC tests,a single cell with PtPr/C as the cathode catalyst achieves a peak power density of 1.92 W·cm-2 and a mass activity of 0.28 A·mg-1Pt,significantly outperforming the cell with commercial Pt/C.XPS and DFT calculations reveal that Pr induces surface electronic reconstruction in the alloy,and the ligand effect tunes the Pt electronic structure by lowering the d-band center.The adsorption/desorption behavior of oxygen-containing intermediates at the three-phase interface has been optimized,thereby promoting the ORR kinetics.This work provides a valuable reference for the development of efficient low-platinum electrocatalysts.
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