MS19-P02 Solvent-free synthesis of heterometallic metal-organic frameworks for the electrocatalytic reduction of carbon dioxideHerein we report the solvent-free synthesis and doping of the benchmark HKUST-1(Cu) as a facile route to afford heterometallic MOFs and their proficient behaviour as electrocatalytic materials in the carbon dioxide reduction to alcohols. Precisely, Zn(II), Ru(III) and Pd(II) were selected as doping metals (MD) with the aim of partially replacing the Cu(II) atoms of the pristine structure to afford HKUST-1(Cu,MD) type materials.
The introduction of a doping element implies a slight increase of the cell parameter with respect to the homometallic HKUST-1. This fact is attributable to the occurrence of longer M ··· Ocarboxylate coordination bond distances that implies the presence of the dopant in the paddle-wheel shaped dinuclear [M2(OOC)4] secondary building unit. In the case of Ru(III) and Pd(II), which are elements of the second transition series, their greater ionic radii values are consistent with an increase in coordination bond distances and cell parameters. On the contrary, Zn(II) exhibits a rather similar ionic radius to that of Cu(II), but the Jahn-Teller effect of Cu(II) (d9) implies shorter equatorial coordination distances than those found in analogous paddle-wheel shaped Zn(II) complexes.1
Prepared samples were processed as gas diffusion electrodes (GDEs) and assembled in a continuous flow filter-press electrochemical cell with the aim of converting CO2 into added-value chemicals.2 The obtained products are mainly methanol and ethanol with Faradaic efficiencies that range from 6 to 60%, which are values comparable or greater than those provided by conventionally used elemental copper and copper oxides.
 Groom, C. R.; Bruno, I. J.; Lightfoot, M. P. and Ward, S. C. (2016). Acta Cryst., B72, 171.
 Albo, J.; Vallejo, D.; Beobide, G.; Castillo, O.; Castaño, P. and Irabien. A. (2016). ChemSusChem, 9, 1-11.
Keywords: Heterometallic MOFs, solvent-free synthesis, CO2 reduction.