Triangulene Synthesis Made Simple on Single-Atom-Doped Gold and Silver Surfaces

Triangulene, the smallest triplet-ground-state polybenzenoid, has previously been successfully synthesized by tip-manipulation experiments, employing scanning probe techniques to dehydrogenate precursor molecules under ultrahigh vacuum and low-temperature conditions. Here, we propose an alternative approach to form triangulene on (111)-facets of gold and silver doped by single noble metal atoms (Ru, Rh, Pd, or Pt), predicted by density functional theory calculations in combination with microkinetic analysis. Our results convey two key insights. First, the isolated single atoms reduce the activation energies for the dehydrogenation of dihydrotriangulene (the precursor molecule) and make the reactions more favored compared to pure Au(111) and Ag(111). In particular, we find that Rh- and Ru-doped surfaces outperform other considered single-atom-doped surfaces with nearly 100% yield of triangulene when the initial coverage of precursor is low. Second, two independent descriptors─the H and intermediate adsorption energies─are found to predict the triangulene formation activity on the single-atom-doped surfaces via scaling relations for activation and reaction energies. Based on these descriptors, a two-dimensional yield map for triangulene formation is constructed, providing valuable design insights for experimentalists. Our theoretical work suggests a straightforward thermal synthesis pathway for triangulenes, offering a more efficient alternative to prevalent tip-induced manipulation techniques and high-temperature approaches.