Chemical reactivity of graphene doped with 3d transition metals: nothing compares to a single vacancy.

Context: Finding catalysts that do not rely on the use of expensive metals is one of the requirements to achieve sustainable production. The reactivity of graphene doped with 3d transition metals was studied. All dopants enhanced the reactivity of graphene and performed better than Stone-Wales defects and divacancies, but were inferior to monovacancies. For hydrogenation of doped-monovacancies, Sc, Ti, Cr, Co, and Ni induced more prominent reactivity on the carbon atoms. However, the metals were the most reactive center for V, Mn, and Fe-doped graphene. Cu and Zn turned the four neighboring carbon atoms into the preferred sites for hydrogenation. The addition of oxygen to doped graphene with Ti, V, Cr, Mn, Fe, Co, and Ni on a monovacancy revealed a more uniform pattern since the metal, preferred to react with oxygen. However, Sc induced a larger reactivity on the carbon atoms. The affinity of the 3d metal-doped graphene systems towards oxygen was inferior to that observed for single-vacancies. Therefore, vacancy engineering is the most favorable and least expensive method to enhance the reactivity of graphene.

Methods: We applied Truhlar's M06-L method accompanied by the 6-31G* basis sets to perform periodic boundary conditions calculations as implemented in Gaussian 09. The ultrafine grid was employed and the unit cells were sampled employing 100 k-points. Results were visualized employing Gaussview 5.0.1.