Thermoplasmonic Heat Generation Efficiency by Nonmonodisperse Core–Shell Ag⁰@SiO₂ Nanoparticle Ensemble

Abstract

The plasmon-induced heat generation by core–shell Ag0@SiO2 nanoparticle ensemble, i.e., Ag0 nanoparticles coated with a nanometric, amorphous SiO2 layer, has been studied for nanoparticles dispersed in liquid suspensions or deposited in film. Nonmonodispersed, fractal-like Ag0@SiO2 ensembles were synthesized by flame spray pyrolysis, varying Ag0 particle size distribution, and SiO2 shell thickness, ranging from 1 nm up to 5 nm. The particles were characterized by TEM, XRD, XPS, and UV–vis, while the thermoplasmonic heat-generation efficiency was monitored in situ by measuring the temperature rise over the nanoparticle ensembles by an infrared thermal imager under UV–vis irradiation or ambient solar light. We have carried out a systematic investigation of parameters regarding (i) the particle characteristics, (ii) the surrounding medium, and (iii) the irradiation characteristics. The data reveal the determinant role played by the SiO2 shell in the plasmonic heating by Ag0@SiO2. Thus, for the thinner SiO2 coating tailored herein (∼1 nm), under focused solar light, Ag0@SiO2 films were able to produce a significant temperature rise up to T max ∼ 400 °C. The data are analyzed quantitatively within the theoretical frame of Mie theory as extended by Baffou for multiple plasmonic nanoheaters, where we take into account the fractal dimension of the flame-made Ag0@SiO2 ensemble and the occurring collective thermal effects in this geometry. In this context, we interpreted the observed phenomena in terms of the neighboring Ag0–Ag0 coupling within each fractal and the dual role of SiO2 as the dielectric shell medium around the metallic core, as well as the plasmonic separator. Accordingly, we provide a consistent theoretical frame which provides a quantitative hierarchy of the physicochemical parameters, which determine the photoinduced heat generation for realistic nonideal/nonmonodisperse Ag0 ensembles.

Lattice Defects Engineering in W-, Zr-doped BiVO4 by Flame Spray Pyrolysis: Enhancing Photocatalytic O2 Evolution

“…Moreover, there is a strong correlation of calcination with the decline of the O-vacancies population as detected by XPS, see Figure 8. An analogous phenomenon has been reported by other researchers also [21,24,25,31]. Here, our data allow a better comprehension of the necessity of W-doping and O-vacancies occurrence for enhancing O2-evolution.…”

“…The lab-scale FSP reactor used for the synthesis of nanocatalysts has been described recently [ 21 ]. The bismuth precursor was prepared by dissolving Bi-nitrate in (triethylene glycol dimethyl ether/acetic acid (70/30 v / v )) (0.5 M) and sonicated for 30 min at 50 °C.…”

Double-Nozzle Flame Spray Pyrolysis as a Potent Technology to Engineer Noble Metal-TiO2 Nanophotocatalysts for Efficient H2 Production

“…The energy resolution was set to 1.18 eV, and the photoelectron take-off angle was 45 • with respect to the surface normal. Recorded spectra were the average of 4 scans with the energy step set to 0.1-0.2 eV and dwell time of 1 s. The spectral analysis included a Shirley background subtraction and peak deconvolution employing mixed Gaussian-Lorentzian functions in a least-squares curve-fitting program, WinSpec, developed at the Laboratoire Interdisciplinaire de Spectroscopie Electronique, University of Namur, Belgium XPS [36,37].…”

A Hybrid {Silk@Zirconium MOF} Material as Highly Efficient AsIII-sponge

“…The recorded spectra were the average of three scans, with energy step 0.1-0.2 eV and a dwell time of 1 s. The As3d binding energy is calibrated based on the C1s core level at 284.5 eV. The spectral analysis included [i] a Shirley background subtraction, and [ii] peak deconvolution employing mixed Gaussian-Lorentzian functions in a least-squares curve-fitting program (WinSpec, Laboratoire Interdisciplinaire de Spectroscopie Electronique, University of Namur, Belgium) 72,73 . N 2 adsorption isotherms were measured at 77 K using a Quantachrome NOVAtouch LX 2 .…”