UV- and Visible-Light Photocatalytic Activity of Simultaneously Deposited and Doped Ag/Ag(I)-TiO₂ Photocatalyst

Abstract

Ag modification has been demonstrated to be an efficient strategy to improve the photocatalytic performance of TiO2 photocatalysts. However, the previous studies about the Ag modification are only restricted to the surface loading of metallic Ag or Ag(I) doping, investigations have seldom been focused on the simultaneously deposited and doped Ag/Ag(I)-TiO2 photocatalyst. In this study, Ag/Ag(I)-TiO2 photocatalyst was prepared by a facile impregnated method in combination with a calcination process (450 °C) and the photocatalytic activity was evaluated by the photocatalytic decomposition of methyl orange and phenol solutions under both UV- and visible-light irradiation, respectively. It was found that Ag(I) doping resulted in the formation of an isolated energy level of Ag 4d in the band gap of TiO2. On the basis of band-structure analysis of Ag/Ag(I)-TiO2 photocatalyst, a possible photocatalytic mechanism was proposed to account for the different UV- and visible-light photocatalytic activities. Under visible-light irradiation, the isolated energy level of Ag 4d contributes to the visible-light absorption while the surface metallic Ag promotes the effective separation of the following photogenerated electrons and holes in the Ag/Ag(I)-TiO2 nanoparticles, resulting in a higher visible-light photocatalytic activity than the one-component Ag-modified TiO2 (such as Ag(I)-TiO2 and Ag/TiO2). Under UV-light irradiation, the doping energy level of Ag(I) ions in the band gap of TiO2 acts as the recombination center of photogenerated electrons and holes, leading to a lower photocatalytic performance of Ag-doped TiO2 (such as Ag/Ag(I)-TiO2 and Ag(I)-TiO2) than the corresponding undoped photocatalysts (such as Ag/TiO2 and TiO2). Considering the well controllable preparation of various Ag-modified TiO2 (such as TiO2, Ag/TiO2, Ag(I)-TiO2, and Ag/Ag(I)-TiO2), this work may provide some insight into the smart design of novel and high-efficiency photocatalytic materials.

Nanohybrids of Two‐Dimensional Transition‐Metal Dichalcogenides and Titanium Dioxide for Photocatalytic Applications

“…Severals tudies have shown that noble metals such as platinum, [36] gold, [37] ruthenium, [38] and silver [39] are the most efficient co-catalysts due to their large work functions.…”

Metal oxide semiconducting interfacial layers for photovoltaic and photocatalytic applications

“…Doping is one of the means to achieve the above-mentioned characteristics. Metal ions of noble metals (Pt, Pd, Ag, and Au) [166] and transition metals (Cr, Cu, Mn, Zn, Co, Fe, and Ni) [167] are used as dopants [168]. Even non-metals such as C, N, S, and P are used for this purpose [160,161,163,169].…”

Photodegradation of Dye Pollutants Catalyzed by H₃PW₁₂O₄₀/SiO₂ Treated with H₂O₂ under Simulated Solar Light Irradiation

“…In recent years, visible light responsive photocatalysts have been extensively studied. TiO 2 modified systems have been prepared to obtain visible-light reactivity in recent years [15][16][17][18]. Polyoxometalates (POMs) have also been recently studied as efficient photocatalysts for the degradation of organic dyes and it indicates that the photocatalytic activity of POMs is comparable to that of the semiconductor TiO 2 [19][20][21].…”