Synthesis and proton conductivity of large-sized crack-free mesostructured phosphorus-oxide-doped silica monoliths

Large-sized, uniform, crack-free, ordered mesostructured phosphorus-oxide-doped silica monoliths were prepared via optimizing the surface nature of vessels and exhibited an accessible pore structure in the surface after very mild drying and UV irradiation. The structure and morphology of monoliths were characterized using XRD, N2-sorption, and AFM. The 31P-MAS NMR data suggest the presence of phosphorus and the hydrolysis of trymethyl phosphate in the doped sample. The proton conduction of mesostructured monoliths were investigated and the calculated conductivities ranged from 10−7 to 10−4 S cm−1 at the temperatures below 100 °C. Among the monoliths, the doped one exhibited a much higher conductivity than the undoped one, though the phosphorus oxides disrupted the mesostructures.