Cyclodehydrogenation catalyzed by atomic hydrogen

Atomically precise synthesis of nanographenes and graphene nanoribbons on semiconductors and insulators has been a formidable challenge. In particular, the metallic substrates needed to catalyze cyclodehydrogenative planarization reactions of precursor molecules limit subsequent applications that exploit the electronic structure of nanographenes. We demonstrate that, counterintuitively, atomic hydrogen can play the role of a catalyst in the cyclodehydrogenative planarization reaction regardless of the substrate type. The high efficiency of the method was demonstrated by the nanographene synthesis on metallic Au, semiconducting TiO2, as well as on inert and insulating Si/SiO2 and thin NaCl layers.