Ray Sekhar Chandra, Mishra Dilip Kumar, Pong Way-Faung
Department of Physics, Faculty of Engineering and Technology (ITER), Siksha "O" Anusandhan Deemed to be University, Bhubaneswar 751 030, Odisha, India.
Department of Physics, CSET, University of South Africa, Florida Science Campus, Private Bag X6, Christiaan de Wet and Pioneer Avenue, Florida Park, Florida 1710, Johannesburg, South Africa.
ACS Omega. 2024 Sep 12;9(38):40067-40074. doi: 10.1021/acsomega.4c05962. eCollection 2024 Sep 24.
Optimization of electronic/magnetic behaviors of chemically decorated diamagnetic noble-metal gold nanoparticles (Au-NPs ≈5 at. %) on multiwalled carbon nanotubes (MWCNTs) and reduced graphene oxide (r-GO) is studied for future uses of optoelectronic/magnetic and biomedical applications. The changes between Au 4f and Au 4f ≈ 3.7 eV in X-ray photoelectron spectroscopy and 1.1 (±0.3) eV shifts in the C -edge in X-ray absorption near edge structure spectroscopy confirm that the reduced form of Au was present in the Au-NP-decorated nanocomposites. The potential difference (ΔV) is built due to charge creations at the interface of r-GO/MWCNTs and Au-NPs and shifts in the Fermi level (Δ ) due to electronic transfer effects, and as a result, the work functions are reduced from 3.2 eV (MWCNTs) to 3.0 eV (MWCNTs:Au-NPs) and 3.1 (r-GO) to 2.8 eV (r-GO:Au-NPS), respectively. Negligible remanence/coercivity in MWCNTs/r-GO (/Au-NPs) with blocking temperature ≈300 K in MWCNTs:Au-NPs accounted for the existence of diamagnetic Au-NPs in these nanocomposites, which implies a superparamagnetic nature. These results furnish the evidence about the optimization of magnetic behaviors of r-GO/MWCNTs (/Au-NPs) that may possibly be altered as a novel contrast agent for clinical magnetic resonance imaging, drug delivery, and hyperthermia applications.
研究了化学修饰的抗磁性贵金属金纳米颗粒（Au-NPs≈5原子%）在多壁碳纳米管（MWCNTs）和还原氧化石墨烯（r-GO）上的电子/磁行为优化，以用于未来的光电子/磁和生物医学应用。X射线光电子能谱中Au 4f和Au 4f≈3.7 eV之间的变化以及X射线吸收近边结构光谱中C边1.1（±0.3）eV的位移证实，在Au-NP修饰的纳米复合材料中存在还原态的Au。由于r-GO/MWCNTs和Au-NPs界面处的电荷产生以及电子转移效应导致费米能级的移动（Δ），从而产生了电位差（ΔV），结果，功函数分别从3.2 eV（MWCNTs）降低到3.0 eV（MWCNTs:Au-NPs）以及从3.1（r-GO）降低到2.8 eV（r-GO:Au-NPS）。MWCNTs/r-GO（/Au-NPs）中剩余/矫顽力可忽略不计，MWCNTs:Au-NPs中的阻塞温度约为300 K，这说明了这些纳米复合材料中抗磁性Au-NPs的存在，这意味着具有超顺磁性。这些结果提供了关于r-GO/MWCNTs（/Au-NPs）磁行为优化的证据，其可能作为一种新型造影剂用于临床磁共振成像、药物递送和热疗应用而被改变。
