Palladium nanoparticles anchored to anatase TiO₂ for enhanced surface plasmon resonance-stimulated, visible-light-driven photocatalytic activity

Abstract

SummaryFreely assembled palladium nanoparticles (Pd NPs) on titania (TiO2) nano photocatalysts were successfully synthesized through a photodeposition method using natural sunlight. This synthesized heterogeneous photocatalyst (Pd/TiO2) was characterized through field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), BET surface area, UV–vis diffuse reflectance spectra (UV-DRS), Raman and photoluminescence (PL) analyses. The simple and smart synthesis anchored well the deposition with controlled Pd NPs size ranging between 17 and 29 nm onto the surface of TiO2. Thus, it gives the characteristic for Pd NPs to absorb light in the visible region obtained through localized surface plasmon resonance (LSPRs). Apparently, the photocatalytic activity of the prepared photocatalysts was evaluated by degrading the endocrine disrupting compound (EDC) amoxicillin (AMX) excited under an artificial visible light source. In the preliminary run, almost complete degradation (97.5%) was achieved in 5 h with 0.5 wt % Pd loading and the degradation followed pseudo-first-order kinetics. The reusability trend proved the photostability of the prepared photocatalysts. Hence, the study provides a new insight about the modification of TiO2 with noble metals in order to enhance the absorption in the visible-light region for superior photocatalytic performance.

Noble metal modified TiO2 microspheres: Surface properties and photocatalytic activity under UV–vis and visible light

“…Among all the noble-metal@TiO 2 composites, Au@TiO 2 exhibits a high yield (63%) and selectivity (91%) for the catalytic oxidation of benzene to phenol in aqueous phenol under visible light. They explained that the probable mechanism of this reaction is based on the electron transfer from the Au NPs to TiO 2 particles, and the electron-depleted Au oxidizes phenoxy anions to form phenoxy radicals that oxidize benzene to phenol[48].Concluding, it is well known that preparation of photoactive plasmonic photocatalysts requires homogeneous distribution of noble-metal NPs on the TiO 2 surface as well as a good contact between the NPs and TiO 2 , because the properties of noble metal -semiconductor nanocomposites depend strongly on the size and dispersion of noble-metal NPs and on the extent of the metal-semiconductor contact at the interface[56,[86][87][88]. When noble metal contacts with TiO 2 , electrons transfer from TiO 2 to NPs is observed, which enhances the electron-hole separation and the transfer of the trapped electron to the adsorbed O 2 which…”

“…9D). It is know from the literature, that palladium plays an important role in the interfacial charge transfer and in a decrease in the rate of electron-hole recombination, because Pd NPs act as an effective electron scavenger to trap the photo induced electrons and holes of TiO 2 leading to the reduction of electron-hole recombination[88]. Leong et al synthesized a series of PdTiO 2 photocatalysts (0.5; 1.0 and 3.0 wt %) and noticed the lowest emission peaks for 1.0 wt% Pd/TiO 2[88].…”

Reduced graphene oxide and Ag wrapped TiO2 photocatalyst for enhanced visible light photocatalysis

“…[12][13][14][15][16] Considering noble metal as a potential impurity turned out to be an alternative approach for reconstructing the weaknesses of TiO 2 . 17,18 Further to improve the optical absorption and enhancing the charge carrier transport, reduced graphene oxide (RGO) was used in the hybrids thus narrows the bandgap and minimize the electron-hole recombination rate. 19 This is due to its rich characteristics in exhibiting high thermal conductivity, great charge carrier mobility, good surface contact with supported nanoparticles (NPs), and high hydrophobicity.…”

Evolution of Ternary AuAgPd Nanoparticles by the Control of Temperature, Thickness, and Tri-Layer

“…For instance, a peak in the UV regime (~380 nm) and a wide shoulder in the NIR regime were commonly observed in all samples. On the other hand, the reflectance was significantly attenuated in the visible region, i.e., 420-600 nm making a wide dip centered ay~460 nm, which might be the absorption enhancement due to the surface plasmon resonance of alloy NPs [37][38][39]. The peak observed in the UV region and NIR region can be due to the quadrupolar and dipolar resonance mode of alloy NPs, respectively, which has been previously observed in the case of pure Ag and Pd NPs [27,29].…”