Can atomic buckling control a chemical reaction? The case of Dehydrogenation of Phthalocyanine Molecules on GdAu2/Au(111)

The efficiency of chemical reactions on surfaces is traditionally related to their lattice structures. The periodic out-of-plane lattice distortions of supported two-dimensional layers offer an alternative strategy to surface functionalization, scarcely investigated so far. Here, we show that the variable buckling geometry of a GdAu2 Moiré overlayer supported on the Au(111) surface exposes specific single-atom sites that control the dehydrogenation process of phthalocyanine (H2-PC) molecules, limiting their reactivity to about 1/3 of the monolayer. The lattice mismatch between the substrate and the alloy layer leads to the previously reported outward displacement of distinct Gd sites. We show that these atomic sites promote the selective dehydrogenation of H2-PC molecules.This project has received funding from the EU-H2020 research and innovation program (grant number 654360) having benefitted from the access provided by Istituto Officina dei Materiali in Trieste (Italy) within the framework of the NFFA Transnational Access Activity. L.V., A.B., and A.C. acknowledge the economic support of the Spanish Ministry of Economy, Industry and Competitiveness (grant number MAT2016-78293-C6-5-R) and Prof. S. Modesti for his help with the electronics. A.B. acknowledges Vicerrectorado de Investigacion of the University of the Basque Country (UPV/ EHU) for the PhD fellowship (2016