Ultrasound-Assisted Fabrication of AgBr/Ag₃PO₄/TiO₂Nanorod Heterostructure on Ti Mesh

Abstract

TiO 2 nanorod (TNR) deposited by AgBr/Ag 3 PO 4 nanoparticles was fabricated on Ti mesh substrate through ultrasound-assisted successive ionic layer adsorption and reaction technology. It was revealed that the ultrasound-assisted process is helpful in ensuring uniform deposition of Ag 3 PO 4 on the surface of TNR and in inhibiting the accumulation of Ag 3 PO 4 nanoparticles. The concentration of KBr and the adsorption duration strongly influence the deposition of AgBr. The enhanced photocatalytic activity of Ag 3 PO 4 /TNR toward methyl orange compared to that of pure TNR is attributed to the enhanced adsorption ability of visible light and to the efficient charge carrier separation owing to the surface plasmon resonance (SPR) effect of Ag 3 PO 4 /Ag/TNR system. The further enhanced photocatalytic activity of the heterostructured AgBr/Ag 3 PO 4 /TNR is attributed to the SPR effect resulting from the evolution of AgBr/Ag/Ag 3 PO 4 /TNR heterostructures and the synergistic energy band structure of Ag 3 PO 4 , AgBr, and TNR.Steadily worsening environmental pollution and energy shortages have raised human awareness of a potential global crisis. 1 Photocatalytic degradation is considered to be an attractive strategy for water decontamination due to its fast and complete mineralization of pollutants without leaving behind any harmful residues. TiO 2 is one of the most renowned photocatalysts due to its chemical stability, nontoxicity, low cost, and favorable optoelectronic properties. 2 However, the fast recombination of photogenerated electrons and holes, and the low efficiency for utilizing visible light are the two major drawbacks restricting its practical applications. Therefore, efforts have been paid to improve the photocatalytic performance of TiO 2 .A dimension-controlled TiO 2 -based nanostructure array is believed to increase the separation rate of photogenerated electrons and holes because of its unique reaction sites, increased optical path lengths, and low reflection, direct electronic carrier transport path ways. 3-5 Meanwhile, flexible substrates with large surface area are believed to increase the absorption of light. Guo 6 reported nanostructure TiO 2 nanorod (TNR) arrays grown on carbon fibers for dyesensitized solar cell (DSSC) use. Liao et al. have also indicated that TiO 2 nanotube arrays synthesized on Ti mesh have achieved enhanced efficiency of DSSC compared to that of TiO 2 nanotube arrays prepared on Ti foil. 7 On the other hand, varied strategies have been used to increase the utilization of the visible range of the solar spectrum, such as modification with dopant, 8,9 sensitization with CdS, CdSe, 10,11 hydrogenation, 12,13 etc. In recent years, photocatalysts of Ag-AgX (X = Cl, Br, I, S), 14-16 Ag 3 PO 4 , 17,18 Ag 3 CO 3 , 19,20 and Ag 3 VO 4 21 have attracted considerable attention as visible light photocatalysts for specific applications. However, a single Ag-based component may be not a good photocatalyst due to its easy decomposition into Ag under light irradiation 22 and the high elec...