Cu0-loaded SBA-15@ZnO with improved electrical properties and affinity towards hydrogen

Abstract

A core-shell material was prepared using SBA-15 crystallites as cores for the growth of a ZnO shell, followed by Cu0 dispersion. The resulting Cu/SBA-15@ZnO nanostructure displayed higher specific surface area (SSA) and higher number of smaller pores as compared to the starting materials. Dispersion of fine Cu0NPs induced a compaction of the host matrice and a marked decay of the hydrophilic character, explained in terms of the involvement of terminal hydroxyl groups in competitive HO:Cu interaction at the expense of H-bridges with water. Heating at 400–450°C seems to trigger ZnO dehydroxylation with possible self-polycondensation and/or the formation of Si-O-Zn bridges. This is an additional explanation of the significant SSA increase and decrease in the average pore diameter. Both ZnO and Cu0NP incorporation induced shifts in the UV–vis absorption band towards higher wavelengths, indicating a decrease in the optical band gap energy and an improvement of the conductance properties. As compared to ZnO, Cu0NPs produced stronger improvement of the conductance, which was found to increase with higher frequencies. Cu/SBA-15@ZnO also displayed higher affinity towards hydrogen as compared to SBA-15@ZnO and SBA-15 at ambient conditions. These outstanding properties combined to an appreciable thermal stability are worth to be prone to deeper investigations, because they can open promising prospects for Cu/SBA-15@ZnO as sensor, electrode material, electrocatalyst and/or hydrogen capture matrice.