Nanomaterials

In the original publication [...]

Carbon-based quantum dots and their nitrogen- and sulfur-doped derivatives were used as platforms to improve the aqueous solubility for Paclitaxel, Violacein and Tetrandrine, drugs with known high partition coefficients (Log P). Paclitaxel, Violacein and Tetrandrine showed a significant reduction in their partition coefficient values by coupling with the carbon-based quantum dots. Paclitaxel’s partition coefficient value decreased from 3.96 to 0.2, Violacein’s from 3.34 to 1.17, and Tetrandrine’s from 2.5 to 1.57, thus demonstrating a significant reduction in their hydrophobicity without being encapsulated. The efficiency of each type of carbon-based quantum dot in lowering each drug’s Log P varied and this behavior was correlated with the nature of the surface interaction between each drug and each of the carbon-based quantum dots.

In this work, we investigate the activation of CO₂ on bimetallic Ni–Fe catalysts, using Fe as the base metal and Ni as a dopant at low concentrations. Our aim is to evaluate how the presence of Ni, either as a substitutional atom or as an adatom, influences CO₂ activation and facilitates subsequent C–O bond breaking. The catalytic surfaces were modeled using Fe(100) slabs, and the effect of Ni was examined in three configurations: (I) substitution of one Fe atom by Ni in the first layer, (II) Ni as an adatom, and (III) Fe as an adatom on the Ni-substituted Fe surface. In all cases, the optimized geometries lead to CO₂ activation. The corresponding energy profiles for C–O bond dissociation were obtained and compared with those on pure Fe(100) (E_act = 0.84 eV). Among the three systems, the configuration with substitution of Fe by Ni in the first layer exhibits the lowest activation barrier for C–O bond breaking, just 0.48 eV—a substantial reduction of 0.36 eV relative to pristine Fe(100). Only the Ni_ad-Fe(100) surface yields a higher barrier (0.93 eV). These results are rationalized by extracting the spin splitting from the spin-resolved LDOS of the metal d-band centers, revealing that the superior performance of Ni₁-Fe(100) arises from a more efficient local spin reorganization during bond dissociation.