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One-Step Photochemical Synthesis of Transition Metal - Graphene Hybrid for Electrocatalysis
摘要： For widespread use of renewable energy such as water splitting, the development of electrocatalysts on a large-scale at a low-cost that remains safe and environmentally friendly is still a great challenge. Here, we report the use of α-aminoalkyl radicals in a one-step procedure that synthesizes transition metal nanoparticle - graphene composites via photoreduction. The organic photocatalyst 2-Methyl-1-[4-(methylthio)phenyl]-2-(morpholinyl) phenyl]-1-butanone (I-907) undergoes Norrish Type I photocleavage to generate strongly reducing α-aminoalkyl radicals, when exposed to UVA. For the first time we demonstrate its ability to reduce graphene oxide (GO) and successfully synthesize Co3O4 nanoparticles decorated on graphene (Co3O4NP-rGO). The α-aminoalkyl radicals simultaneously reduce GO and Co2+ salts which nucleates on the negatively charged GO sheets and grows to form nanoparticles. The resulting Co3O4NP-rGO showed decent catalytic activity and stability for the Oxygen Evolution Reaction (OER). Our work introduces a new and environmentally friendly synthesis procedure that can be used to produce earth abundant transition metal electrocatalysts.
关键词： photochemical synthesis,reduced graphene oxide,Graphene oxide,α-aminoalkyl radicals,water oxidation,metal nanoparticles
更新于2025-11-19 16:56:35
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Photo-chemically derived Plasmonic Semiconductor Nanocrystals as Optical Switch for Ultrafast Photonics
摘要： Establishing new photonic material with large optical nonlinearity in the near-infrared regime is significant for ultrafast optical science and devices. In this paper, we developed a facile photochemical approach to fabricate covellite CuS plasmonic nanocrystals (NCs) with high chemical stability and strong oxidation resistance under ambient conditions. The photo-chemically derived CuS NCs possess strong absorption in the visible-to-near-infrared optical range caused by the localized surface plasmon resonance effect (LSPR). We further demonstrate superior saturable absorption behavior of CuS NCs with large modulation depth and high damage threshold. By using CuS as an optical switch, a highly-stable mode-locked pulsed laser operating in the telecommunication band with signal-to-noise ratio over 70 dB and pulse duration of 1.57 ps has been achieved. Our results suggest that the photochemical method is an effective technique to fabricate plasmonic NCs, which can be developed as an excellent candidate for ultrafast photonic devices in the visible-to-near-infrared region.
关键词： Optical switch,CuS nanocrystals,Photochemical synthesis,Ultrafast photonics,Plasmonic semiconductor nanocrystals
更新于2025-09-23 15:19:57
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Photochemical Synthesis of Silver Nanodecahedrons under Blue LED Irradiation and Their SERS Activity
摘要： Silver nanodecahedrons were successfully synthesized by a photochemical method under irradiation of blue light-emitting diodes (LEDs). The formation of silver nanodecahedrons at different LED irradiation times (0–72 h) was thoroughly investigated by employing different characterization methods such as ultraviolet–visible spectroscopy (UV–Vis), transmission electron microscopy (TEM), and Raman spectroscopy. The results showed that silver nanodecahedrons (AgNDs) were formed from silver nanoseeds after 6 h of LED irradiation. The surface-enhanced Raman scattering (SERS) effects of the synthesized AgNDs were also studied in comparison with those of spherical silver nanoparticles in the detection of 4-mercapto benzoic acid. Silver nanodecahedrons with a size of 48 nm formed after 48 h of LED irradiation displayed stronger SERS properties than spherical nanoparticles because of electromagnetic enhancement. The formation mechanism of silver nanodecahedrons is also reported in our study. The results showed that multihedral silver nanoseeds favored the formation of silver nanodecahedrons.
关键词： LEDs,photochemical synthesis,SERS,silver nanodecahedron
更新于2025-09-23 15:19:57
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PbS and PbS/CdS quantum dots: Synthesized by photochemical approach, structural, linear and nonlinear response properties, and optical limiting
摘要： In this work, PbS and PbS/CdS core–shell quantum dots (QDs) were synthesized by a new photochemical approach. Prepared QDs were characterized by means of x-ray diffraction (XRD), ?eld emission scanning electron microscopy (FESEM), energy dispersive x-ray analysis (EDAX), UV–Vis, and Z-scan analyses. Synthesized QDs were in a cubic phase with a spherical morphology, and the crystallite sizes are estimated using the strain–size method. A uniform shift of Bragg diffraction peaks and quenching (200) Bragg plane are interpreted as the growth of the CdS shell. Linear optical properties were investigated using Urbach analysis and Tauc formula. It was found that the density of states of QD conduction and valence bands are three dimensional. The estimated sizes of PbS QDs and PbS/CdS using exciton absorption peaks at room temperature are 1.8 and 2.7 nm, respectively, which are in good agreement with the strain–size plot analysis. The growth of the CdS shell resulted in a considerable decrease in the nonlinearity refractive index and a signi?cant increase in the nonlinear absorption.
关键词： PbS/CdS,photochemical synthesis,PbS,optical limiting,quantum dots,nonlinear optical properties
更新于2025-09-19 17:13:59