Dilute alloying-induced d–p orbital hybridization in Pd–Bi metallene arrays for electrocatalytic coupling of carbon dioxide and nitrate to urea

Electrocatalytic urea synthesis from CO2 and NO3− offers a dual solution for greenhouse gas mitigation and industrial effluent valorization, while enabling renewable energy storage. Rational design of advanced catalysts for urea electrosynthesis represents a scientifically critical yet persistently challenging endeavor. In this study, we developed Pd–Bi dilute alloy metallene arrays grown on Cu foam (Pd–Bi/CF) by a two-step galvanic replacement strategy. The optimized Pd10–Bi90/CF could deliver a notable urea yield rate of 2165.2 μg h−1 cm−2 with 45.3% faradaic efficiency at −0.25 V vs. reversible hydrogen electrode (RHE). Experimental and computational studies validated that d-p orbital hybridization between d-block Pd and p-block Bi in Pd10–Bi90/CF modulates the electronic structure of active sites, thereby facilitating adsorption and activation of NO3− and CO2, synergistic generation of key intermediates *NH2 and *CO, and selective C–N coupling toward urea synthesis. This study demonstrates a viable pathway toward optimizing Bi-based catalysts for electrocatalytic urea synthesis.