Electrolytic Synthesis of Aqueous Aluminum Nanoclusters and in situ Characterization by Femtosecond Raman Spectroscopy and Computations
Abstract : The selective synthesis and in situ characterization of aqueous Al-containing clusters is a long-standing challenge. We report a new integrated platform that combines: (i) a selective, atom-economical, step-economical, scalable synthesis of Al-containing nanoclusters in water via precision electrolysis with strict pH control; and (ii) an improved femtosecond stimulated Raman spectroscopic method covering a broad spectral range of ca. 350—1400 cm-1 with high sensitivity, aided by ab initio computations, to elucidate Al aqueous cluster structures and formation mechanisms in real time. Using this platform, a new and unique view of flat [Al13(μ3-OH)6(μ2-OH)18(H2O)24](NO3)15 cluster formation is observed in water, in which three distinct reaction stages are identified. The initial stage involves the formation of an [Al7(µ3-OH)6(µ2-OH)6(H2O)12]9+ cluster core as an important intermediate toward the flat Al13 aqueous cluster.
Wang, W.; Liu, W.; Chang, I.-Y.; Wills, L. A.; Zakharov , L. N.; Boettcher , S. W.; Cheong, P. H.-Y.; Fang, C.; Keszler, D. A. Proc. Natl. Acad. Sci. USA 2013, Accepted. DOI: 10.1073/pnas.1315396110