<p>In this work, a facile surfactant-free displacement reaction strategy was developed to successfully construct a PdCu alloy nanocatalyst with a unique 3D porous network structure. Systematic characterizations, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), were conducted to analyze the catalyst’s phase composition, electronic structure, and micromorphology. The experimental results indicated that the Pd₃Cu₁ and Pd₁Cu₁ samples formed single-phase alloy structures, while the Pd₁Cu₃ sample exhibited partial alloying. The obvious electronic synergistic interaction between Pd and Cu tuned the adsorption strength of reaction intermediates. Additionally, the Pd₁Cu₁ catalyst possessed a sponge-like porous network structure, providing abundant active sites and facilitating efficient mass transfer. When evaluated using the reduction of 4-nitrophenol (4-NP) as a model reaction, the Pd₁Cu₁ catalyst displayed the optimal catalytic activity, with an apparent rate constant (<i>k</i>_app) of up to 20.30 × 10⁻³&#xa0;s⁻¹, which was significantly superior to those of the Pd₃Cu₁ and Pd₁Cu₃ samples. Cyclic tests demonstrated excellent cycling stability of the catalyst, with no obvious activity decay observed after 10 consecutive cycles. The surfactant-free preparation method and the PdCu bimetallic synergistic design strategy proposed in this work provided a novel and effective approach for the rational design of efficient and low-cost catalytic systems. The as-prepared PdCu alloy catalysts showed broad application prospects in the field of catalytic reduction.</p> Graphical abstract <p>PdCu nanonetworks were synthesized via a Zn-mediated growth and acid etching strategy, exhibiting efficient electron transfer for the catalytic reduction of 4-nitrophenol</p> <p></p>