An exclusive deposition method of silver nanoparticles on TiO(2) particles via low-temperature decomposition of silver-alkyldiamine complexes in aqueous media

An exclusive deposition method of Ag nanoparticles (NPs) on TiO(2) particles has been developed. Ag NPs supported on TiO(2) particles, Ag(x)/TiO(2), with various Ag weight ratios versus total weights of Ag and TiO(2) between x = 2 and 16 wt% are prepared via low-temperature thermal decomposition of Ag(i)–alkyldiamine complexes generated by a reaction between AgNO(3) and N,N-dimethyl-1,3-propanediamine (dmpda) in an aqueous medium suspending TiO(2) particles. The thermal decomposition of the Ag(i)–alkyldiamine complexes is accelerated by TiO(2) particles in the dark, indicating that the reaction catalytically occurs on the TiO(2) surfaces. Under optimised reaction conditions, the thermal decomposition of the complex precursors is completed within 3 hours at 70 °C, and Ag NPs are almost exclusively deposited on TiO(2) particles with high conversion efficiencies (≥95%) of the precursor complexes. The thermal decomposition rates of the precursor complexes are strongly influenced by the chemical structure of a family of water-soluble dmpda analogues, and dmpda with both primary and tertiary amino groups is adopted as a suitable candidate for the exclusive deposition method. The number-averaged particle sizes of the Ag NPs are 6.4, 8.4, 11.8 and 15.2 nm in the cases of Ag(x)/TiO(2), x = 2, 4, 8 and 16, respectively. To the best of our knowledge, the as-prepared Ag(x)/TiO(2) samples show one of the highest catalytic abilities for the hydrogenation reduction of 4-nitrophenol into 4-aminophenol as a model reaction catalysed by Ag NPs.