Facile self-assembly of PtCu nanodendrites with enhanced performance for oxygen reduction in acidic environments

Precisely tailoring catalytic sites is essential for addressing the inherently slow kinetics of the oxygen reduction reaction (ORR), a major bottleneck in the efficiency of proton exchange membrane fuel cells (PEMFCs). In this work, we present a straightforward one-step self-assembly method for fabricating PtCu nanocrystals (PtCu NCs) with a hierarchical nanodendritic architecture. This 3D structure integrates high-index facets and lattice strain to optimize catalytic performance. The incorporation of Cu into the Pt lattice induces compressive strain, which modulates the electronic structure and weakens the binding of oxygen intermediates. Simultaneously, selective surfactant adsorption suppresses the growth of low-index planes, promoting the formation of catalytically favorable steps and kinks. As a result, the PtCu NCs achieve a mass activity of 1.125 A mgPt −1 and a specific activity of 1.120 mA cm −2 at 0.90 V vs. RHE, corresponding to enhancements of 12.23 and 6.29 times, respectively, compared to those of conventional Pt/C catalysts. After durability tests, the PtCu NCs retain 89.9% of their initial mass activity after 10,000 cycles, compared to only 48.9% for Pt/C. These results highlight the power of compositional and morphological control in advancing ORR electrocatalysts and offer a scalable route toward high-performance PEMFC technologies.