Fabrication and Characterization of Visible-Light-Driven Plasmonic Photocatalyst Ag/AgCl/TiO₂ Nanotube Arrays

Abstract

Conventional TiO 2 photocatalyst possesses excellent activities and stabilities, but requires near-ultraviolet (UV) irradiation (about 4% of the solar spectrum) for effective photocatalysis, thereby severely limiting its practical application. It is highly desirable to develop a photocatalyst that can use visible light in high efficiency under sunlight irradiation. In this work, we prepare new visible-light-driven plasmonic photocatalyst Ag/ AgCl/TiO 2 nanotube arrays (NTs) by depositing AgCl nanoparticles (NPs) into the self-organized TiO 2 NTs, and then reducing partial Ag + ions in the surface region of the AgCl particles to Ag 0 species under xenon lamp irradiation. The prepared metal-semiconductor nanocomposite plasmonic photocatalyst exhibits a highly visible-light photocatalytic activity for photocatalytic degradation of methyl orange in water and stability. A new plasmonic photocatalytic mechanism, which is proposed on the basis of the fact that the Ag NPs are photoexcited due to plasmon resonance and charge separation, is accomplished by the transfer of photoexcited electrons from the Ag NPs to the TiO 2 conduction band and the simultaneous transfer of compensative electrons from a donor (Cl -) to the Ag NPs. The proposed mechanism is further confirmed by the experiments of hydroxyl radical and transient photocurrent response. The prepared photocatalysts are also of great interest in solar cell, catalysis, separation technology, biomedical engineering, and nanotechnology. This study may provide new insight into the design and preparation of advanced visible-light photocatalytic materials.

A review on plasmonic metal⿿TiO2 composite for generation, trapping, storing and dynamic vectorial transfer of photogenerated electrons across the Schottky junction in a photocatalytic system

“…The residual free holes can react with water molecules to generate various reactive oxygen species which acts as an immense oxidizing agent and this was the main mechanism proposed for Ag/TiO 2 /SiO 2 composite catalyst to kill the bacteria by the assistance of light [189]. Ag/AgCl/TiO 2 nanotube arrays was prepared by depositing AgCl nanoparticles into the self-organized TiO 2 and then partially reducing Ag + ions to Ag 0 species on the surface region of AgCl particles under xenon lamp irradiation [190]. The prepared metal-semiconductor nanocomposite plasmonic photocatalyst exhibits high visible-light photocatalytic activity for the degradation of MO in water.…”

Dye-sensitized photoelectrochemical cell on plasmonic Ag/AgCl @ chiral TiO 2 nanofibers for treatment of urban wastewater effluents, with simultaneous production of hydrogen and electricity

“…Regarding the first effect, Ag/AgCl @ chiral TiO 2 nanofibers under visible-light irradiation produces photogenerated electron-hole pairs in the Ag nanoparticles due to surface plasmon resonance (SPR) [30]. In this process, SPR generates the electron-hole pairs in the semiconductor (AgCl and TiO 2 ) by the dipole-dipole interaction between the donor (Ag) and the acceptors (AgCl and TiO 2 ).…”

“…Regarding the effect of the sensitized dye on the removal of TOC and EE2, the redox 13 potential of N719/sensitized N719 is ~ 1.1 V (vs. normal hydrogen electrode (NHE)) 14 [21] and sensitized N719/oxidized N719 is ~ -0.6 V (vs. NHE) [30] which is sufficient 15 to oxidize most organic compounds in wastewater, since their redox potentials were 16 mostly less than 0.6 V vs. NHE [31]. As a result, the reduction of the sensitized dye to 17 its ground state maintained the cell cycle until all organic contaminants were removed 18 from the wastewater.…”

Silver metalized mixed phase manganese-doped titania: Variation of electric field and band bending within the space charge region with respect to the silver content

“…As a result the electrons are transferred from the VB to the CB of Mn-TiO 2 /Ag (0.1%) under solar light irradiation. The electric near-field of the deposited silver particles increases the life span of the electron-hole pair and reduces the recombination process [61][62][63]. The metallic Ag deposit on both anatase and rutile phases plays a crucial role in enhancing the separation of photogenerated charge carriers and increases the efficiency of the photocatalyst.…”