LAUSR

Abstract A series of highly-uniform and mesoporous Co3O4 nanospheres comprising porously-assembled tiny building blocks, and more importantly, with widely tunable sizes from 50 nm up to 500 nm were successfully synthesized for the first time via single facile polyol approach. The crucial synthesizing factors including molecular weight and concentrations of polyvinylpyrrolidone, the fraction of cobalt precursor, and the subsequent calcination temperature and time were systematically varied over a very wide range for extensively understanding their effects on growth mechanisms, uniformity and particularly the minimum assembled size. The present unique mesoporous nanoassemblies evidently lead to not only a higher surface-to-volume ratio for a variety of potential applications but a lower operating temperature for CO sensing compared with that reported for a variety of intrinsic or heterogeneous Co3O4 nanostructures.