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Non-noble nanomaterial-based quasicrystals (QC) are attractive structures due to their potential surface plasmon resonance (SPR) properties and ability to be easily exfoliated into two-dimensional (2D) sheets. Interaction with and sensing of organic molecules are applications where such 2D materials are a viable option due to their large surface area to volume ratio, providing abundant active sites for molecular interactions. In this work, a titanium-based multicomponent alloy (Ti45Zr38Ni17) was exfoliated into a 2D quasicrystal (2D-Ti QC) from its bulk form via liquid-phase exfoliation. Structural and optical experimental techniques were used to characterize the 2D-Ti QC. Its plasmonic nature was verified and demonstrated via the absorbance spectrum, light localization images, and far-field diffraction patterns. Dopamine sensing was demonstrated using the absorbance spectra of optically active 2D-Ti QC. The linear range of detection was obtained as ∼13–91 nM (200–1400 ppb). Molecular dynamics (MD) simulations of Ti QC were conducted to investigate its structural stability. The interaction between 2D-Ti QC and dopamine was investigated by using DFT simulations. In this way, the potential of 2D-Ti QC to be used as an organic molecule sensor has been experimentally and theoretically demonstrated. [ABSTRACT FROM AUTHOR]

Although Ag is a stable enough metal to be used as the electrocatalyst in alkaline fuel cells for the oxygen reduction reaction (ORR), its activity is far less compared to that of the commercial Pt/C. We report here a tailored fabricated Ag-core–AuAg-sandwiched–Ag-shell [(Ag@AuAg)@Ag] nanoscale material for application as a catalyst of an efficient ORR (kinetically sluggish process in the absence of a catalyst) in fuel cells via a stepwise template-mediated process. In this work, we not only showcased the worsened behaviors of Au on the surface to hinder the ORR but also justified its benefits as the core of a nanoscale material to positively influence the facile charge transfer from surface Ag to core Au to follow a four-electron-transfer pathway for ORR by producing water as the main product. This facile electron mobility enhances the Ag oxophilicity and thereby enhances the ORR kinetics. On the contrary, when both Au and Ag are present on the surface, while the core is purely made of Ag, the charge transfer is still facile but the availability of a smaller number of active sites (Ag) reduces the rate of ORR. For materials made of pure Au on the surface, the reaction rate decreases further and proceeds via a two-electron-transfer process, producing hydrogen peroxide. The newly developed electrocatalyst [(Ag@AuAg)@Ag] shows ORR activity comparable to that of Pt/C, but with regard to stability, (Ag@AuAg)@Ag is much better, holding 97% of its current density after 7 h of chronoamperometric studies. [ABSTRACT FROM AUTHOR]

Pb2+ codoping enhances the Tb3+ emission in trivalent terbium-doped zinc sulfide [Zn-(Tb)-S] nanoparticles (NPs). The Tb3+-Pb2+ spatial proximity and a favorable codopant electronic energy level alignment contribute toward this emission brightening. This work tests the performance of the Tb3+ emission in the Zn-(TbPb)S and Zn-(Tb)-S/Pb NPs, where the dopants within parentheses and after slashes indicate their synthetic and postsynthetic doping, respectively. When screened against steady-state and time-resolved photoluminescence, photoelectron spectroscopy, zeta potential, and infrared absorption of surface capping ligands, the Zn-(TbPb)S NPs emerge as a superior sensitizer to generate Tb3+ emission. A core dominant Tb3+-Pb2+ interaction in Zn-(TbPb)S NPs prompts a stronger Tb3+ emission when compared to the surface dominant Tb3+-Pb2+ interaction in Zn-(Tb)-S/Pb NPs. This doping strategy guided the NP design principle to control lanthanide emission, which expands the palette of lanthanide-based NP luminophores for practical applications. The Pb2+‑sensitized Tb3+ emission brightening in the ZnS NPs in the precation exchange reaction conditions can find applications in Pb2+ sensing, cellular imaging, and light emitting diodes (LEDs). [ABSTRACT FROM AUTHOR]

Nanomagnets with regulated magnetic properties are incredibly advantageous in the framework of magnetic resonance imaging (MRI) for medical imaging. This work aims to achieve an improved MRI-contrast signal by considering variation in octahedral site substitution of Zn2+ ions in nanoensembles of Ni1–xZnxFe2O4@CoO (x = 0.25 and 0.50) nanoparticles. We observe enhanced MRI-contrast efficiency in nanoensembles of Ni0.75Zn0.25Fe2O4@CoO with superior ground state magnetization of 210.6 μB/cell and a higher asymmetric coercive field than that of Ni0.5Zn0.5Fe2O4@CoO. In addition, both systems show cell viability to a normal HEK cell line until 0.5 mM and no pro-tumorigenic activity until 1 mM. The ratio of transverse to longitudinal relaxivity (r2/r1) gives a value of 30 for Ni0.75Zn0.25Fe2O4@CoO and 19.5 for Ni0.5Zn0.5Fe2O4@CoO, resulting in promising candidates for MRI-transverse contrast agents with a small metal concentration up to 0.375 mM. A superior MRI-contrast signal is achieved in Ni0.75Zn0.25Fe2O4@CoO. As a result, we successfully achieve enhancement in MRI-contrast efficiency by considering manipulation in octahedral site substitution in cell-viable nanoensembles of Ni1–xZnxFe2O4@CoO (x = 0.25 and 0.50) and attaining the significant association of anisotropy field strength and easy axes alignment toward proton dephasing in the MRI-relaxivity mechanism. [ABSTRACT FROM AUTHOR]