In this work, a first-principles systematic study of (Pt3Cu)n, n = 1–9, clusters was performed employing the linear combination of Gaussian-type orbital auxiliary density functional theory approach. The growth of the clusters has been achieved by increasing the previous cluster by one Pt3Cu unit at a time. To explore in detail the potential energy surface of these clusters, initial structures were obtained from Born–Oppenheimer molecular dynamics trajectories generated at different temperatures and spin multiplicities. For each cluster size, several dozens of structures were optimized without any constraints. The most stable structures were characterized by frequency analysis calculations. This study demonstrates that the obtained most stable structures prefer low spin multiplicities. To gain insight into the growing pattern of these systems, average bond lengths were calculated for the lowest stable structures. This work reveals that the Cu atoms prefer to be together and to localize inside the cluster structures. Moreover, these systems tend to form octahedra moieties in the size range of n going from 4 to 9 Pt3Cu units. Magnetic moment per atom and spin density plots were obtained for the neutral, cationic, and anionic ground state structures. Dissociation energies, ionization potential, and electron affinity were calculated, too. The dissociation energy and the electron affinity increase as the number of Pt3Cu units grows, whereas the ionization potential decreases.

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El objetivo del presente trabajo es crear un consenso acerca del método de exfoliación en fase líquida (LPE) para la producción de grafeno y, a su vez, conocer las causas y los diversos factores que afectan el rendimiento y la calidad del grafeno obtenido. Para lograr este objetivo, se realiza una revisión bibliográfica sistemática usando el buscador de Google Académico por la extensión de su acervo. En el presente escrito los resultados obtenidos de esta revisión bibliográfica exhaustiva de la LPE de grafeno se ordenan de acuerdo con su relevancia, dando prioridad en conocer las causas y los fenómenos físicos claves relacionados con la LPE. Los artículos centrados en entender los fenómenos físicos y químicos que gobiernan la LPE fueron clasificados en la sección mecanismo, con el fin de tener una mejor comprensión del fenómeno a nivel molecular. Con esta información, se propone una clasificación de acuerdo con las técnicas más comúnmente usadas (sonicación, microfluídica, etc) para lograr un consenso sobre las técnicas que se clasifican dentro del método de LPE de grafeno con base en el mecanismo, lo que da pauta al desarrollo de nuevas técnicas que mejoren significativamente el desempeño de este método. De la revisión sistemática se concluye que el método de exfoliación en fase líquida es un método robusto, atractivo para la industria, de fácil escalabilidad y de alto rendimiento en general dependiendo de las técnicas de preparación.

In this work, recent research progresses in the formation of Pt3Cu nanoparticles onto the surface of graphene are described, and the obtained results are contrasted with previously published theoretical studies. To form these nanoparticles, tetrabutylammonium hexachloroplatinate, and copper acetylacetonate are used as platinum and copper precursors, respectively. Oleylamine is used as a reductor and a solvent. The obtained catalyst is characterized via X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy dispersive spectroscopy X-ray (EDS). To assess the catalytic activity, the graphene-supported Pt3Cu material is tested with cyclic voltammetry, “CO stripping”, and oxygen reduction reaction potentiodynamic curves to find the nature and the intrinsic electrochemical activity of the material. It can be observed that the tetrabutylammonium cation plays a critical role in anchoring and supporting nanoparticles over graphene, from which a broad discussion about the true nature of the anchoring mechanism was derived. The growth mechanism of the nanoparticles on the surface of graphene was observed, supporting the conducted theoretical models. With this study, a reliable, versatile, and efficient synthesis of nanocatalysts is presented, demonstrating the potentiality of Pt3Cu/graphene as an effective cathode catalyst. This study demonstrates the importance of reliable ab inito theoretical results as a useful source of information for the synthesis of the Pt3Cu alloy system.