Crystallization time-induced microstructural evolution and photoelectrochemical properties of ternary Ag@AgBr/TiO2 nanorod arrays

The plasmonic Ag@AgBr nanoparticles on a well-ordered TiO2 nanorod array (TNR) matrix were successfully constructed by a secondary hydrothermal strategy. Effects of different crystallization time of Ag@AgBr on crystallinity, size and optical properties of the ternary arrays were discussed. The results showed that the crystalline behavior of Ag@AgBr was improved significantly with the increasing crystallization time. The average size of Ag@AgBr nanoparticles attached to top and side of TiO2 nanorods was 15 nm, and increased up to 55 nm at longer time. The surface plasmon resonance (SPR) bands were evident in the Ag@AgBr/TNR (ABT) arrays, and a significant redshift was observed with crystallization time. Especially when the crys-tallization time is 12 h, 12ABT photoelectrode had the lowest transfer resistance for interfacial charges and the highest transient photocurrent intensity of 130 mu A/cm(2), which was about 13 times that of bare TNR. In the degradation of methyl orange, 12ABT showed the highest photocatalytic efficiency of 95.6% and rate constant of 0.0167 min(-1) under full spectral irradiation, which was 18.6 times of TNR. The favorable sun-light-driven photocatalytic activity originated from synergistic effect of three components in Ag@AgBr/TNR array, such as the improved solar light response through surface plasmon resonance (SPR) and photo-sensitive effect of Ag and AgBr co-sensitizers, as well as the high-efficiency carrier transfer in the unique heterojunction. (C) 2021 Published by Elsevier B.V.

Automated summary

The plasmonic Ag@AgBr nanoparticles were successfully synthesized on a TiO2 nanorod array through a secondary hydrothermal method. The crystallization time of Ag@AgBr was found to significantly affect the crystallinity, size, and optical properties of the ternary arrays. With an increase in crystallization time, the crystalline behavior of Ag@AgBr improved, leading to larger nanoparticles and a redshift in the surface plasmon resonance bands. The Ag@AgBr/TNR arrays exhibited enhanced photocatalytic efficiency in the degradation of methyl orange due to the synergistic effect of improved solar light response and efficient charge transfer.