Fig. 1. DFT studies.

a Geometries of *CO, *CHO, and *OCCOH intermediates on Au–Cu surface, showing the competitive steps of *CO protonation and C–C coupling. b Reaction free energy difference between *CO protonation and C–C coupling steps on Cu₃₆, Au₁Cu₃₅, Au₂Cu₃₄, and Au₃Cu₃₃ surfaces under varying *CO coverages. c Reaction free energies for *H intermediate formation under varying *H coverages on Cu₃₆, Au₁Cu₃₅, Au₂Cu₃₄, and Au₃Cu₃₃ surfaces. Cu, Au, C, O, and H atoms in Fig. 1 are illustrated as orange, yellow, grey, red, and white spheres, respectively, while the water molecules are shown as sticks. Source data are provided as a Source Data file.