Synergistic effect of interfacial lattice Ag⁺and Ag⁰clusters in enhancing the photocatalytic performance of TiO₂

Abstract

An interfacial lattice Ag(+) doped on TiO2 (Ag(+)/TiO2) was prepared by eluting Ag(0) clusters from a hydrothermally prepared Ag(0)/Ag(+)/TiO2 composite. An Ag(+)/TiO2@Ag(0) composite photocatalyst was subsequently obtained via a secondary Ag(0) clusters loading process to the Ag(+)/TiO2. The photocatalytic activity of Ag(+)/TiO2@Ag(0) was greatly improved compared to Ag(0)/Ag(+)/TiO2 and Ag(+)/TiO2. X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV) testing verified that Ag(+) ions occur as an interfacial lattice Ag(+) species in the composites. The enhancement effect of the interfacial lattice Ag(+) species is exhibited by the newly-formed Ag(+)/TiO2@Ag(0) as the interfacial lattice Ag(+) is fully exposed but not overlapped with the re-loaded Ag(0) clusters. The interfacial lattice Ag(+) ions and Ag(0) clusters are both responsible for the photocatalytic performance improvement of the catalyst, in either the photocatalytic degradation of methyl orange or photocurrent measurement.

Highly Efficient, Low-Cost, and Magnetically Recoverable FePt–Ag Nanocatalysts: Towards Green Reduction of Organic Dyes

“…The XPS spectrum of Pt exhibits double peaks with binding energies of 71.1 and 74.2 eV, corresponding to the standard peaks of pure Pt 4f 7/2 and Pt 4f 5/2 [ 63 , 64 ]. The binding energy of FePt–Ag 10 mg–60 mL is located at 367.4 and 373.4 eV, which can be assigned to Ag 3d 5/2 and Ag 3d 3/2 , and matches well with the standard XPS spectrum of metallic Ag [ 53 , 54 ]. It should be pointed out that the intensity of Fe 2p and Pt 4f decreases and the intensity of Ag 3d increases with the increase of the additive amount of the silver colloids, since the intensity of XPS spectra is proportional to the atomic concentration [ 65 ].…”

“…The morphology and detailed structure of the samples were investigated by SEM and TEM. In particular, the TEM technique is a direct and important methodology for structure analysis in the materials engineering technologies [ 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 ]. Figure 4 shows typical low-magnification TEM images of pure FePt nanocrystals, pure silver colloids, and FePt–Ag 5 mg–60 mL and FePt–Ag 10 mg–60 mL nanocomposites.…”

Improving photocatalytic performance of ZnO via synergistic effects of Ag nanoparticles and graphene quantum dots

“…The roles of the Ag NPs in these composites can be described as follows. (1) The phenomenon of localized SPR of the Ag NPs increases their absorbance of visible light, producing energetic electrons. (2) The presence of Ag NPs in the precursor solution prevents the growth of the ZnO flower-like nanostructures, resulting in small-sized ZnO nanostructures with a high specific surface area for the photocatalytic reaction.…”

“…In recent years, semiconductor metal oxides with suitable bandgaps have attracted considerable scientific attention for their use in the photocatalysis field. [1][2][3] In particular, ZnO represents a new class of semiconductors that have been investigated extensively, because of their relatively high photosensitivity, nontoxic nature, photochemical stability and low cost. 4,5 However, ZnO exhibits low photocatalytic activity due to its distinct characteristics, including its low utilization of visible light, given its wide bandgap (3.37 eV), 6 and because it allows for the rapid recombination of the photoexcited electron-hole pairs; this process occurs on the nanosecond timescale and has faster kinetics than those of surface redox reactions.…”

Titania-Supported Palladium/Strontium Nanoparticles (Pd/Sr-NPs@P25) for Photocatalytic H2 Production from Water Splitting

“…But the major disadvantages of TiO 2 limiting the photocatalytic performance are (i) the fast recombination of photoexcited electrons and holes (e – /h + ) and (ii) the too large bandgap (3.2 eV, i.e., only active under ultraviolet light). Various modifications (e.g., loading of noble metals, doping with nonmetal elements, and formation of composites) have been conducted on the TiO 2 to promote interfacial redox processes by enhancing the separation of photogenerated electrons and holes. − The influences of factors such as the preparation methods, metal dispersion on titania, and formation of heterojunctions are of importance. , The fast recombination issue can also be leveraged by changing the surface properties of semiconductor via fluorination and addition of electron acceptors and sacrificial reagents in the reaction medium. , To overcome the second issue (i.e., too large bandgap), modification of the band structure has been carried out via different strategies such as coupling with a narrow band structure, codoping with foreign ions, metal/nonmetal ion incorporation, surface sensitization by organic dyes, and noble metal depositing/loading.…”