Composition-controlled synthesis of Pt–Pd–Cu ternary metal nanoparticles for an enhanced electrocatalytic hydrogen evolution reaction

Developing efficient and cost-effective electrocatalysts for the hydrogen evolution reaction (HER) is critical for advancing green hydrogen production. In this study, we synthesized Pt-Pd-Cu ternary nanoparticles (NPs) with tunable compositions <i>via</i> a one-pot solvothermal method, highlighting the pivotal role of Pd as an "electron bridge" to optimize electronic interactions and HER performance. By precisely tuning the precursor ratios of Pd and Cu, we achieved PtPd_<i>x</i>Cu_1-<i>x</i> NPs with uniform size and tailored compositions, demonstrating exceptional control over alloy formation through a scalable synthesis approach. Regarding the HER, as the Cu content increases, an inverse-volcano-shaped overpotential at 10 mA cm^-2 becomes evident. Specifically, PtPd_0.8Cu_0.2 exhibits optimal performance, with an overpotential of merely 31.0 mV. In addition, the decrease in Tafel slope from 169.6 mV dec^-1 to 58.7 mV dec^-1 indicates that the rate-determining step shifts from mass diffusion to electron transfer. Moreover, the impacts of composition and reaction time on the preparation were thoroughly investigated, and the unconventional process of reduction was put forward. Additionally, the method was extended to synthesize other ternary PtCu_0.5M_0.5 NPs. Among various elements, only tin, lead, and gold could completely replicate the synthesis process, and high-entropy alloys are successfully prepared based on these selected metals. This research provides valuable insights into the synthesis and properties of Pt-based NPs and their potential applications in the HER.