View PDF VersionPrevious ArticleNext Article
 
DOI: 10.1039/C5CP90142A (Editorial) Phys. Chem. Chem. Phys., 2015, 17, 27920-27921

Recent advances in the chemical physics of nanoalloys

Riccardo Ferrando *a, Roy L. Johnston *b and Catherine Louis *c
aDepartment of Chemistry and Industrial Chemistry, University of Genoa, Via Dodecaneso 31, 16146, Genoa, Italy. E-mail: ferrando@fisica.unige.it
bSchool of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK. E-mail: r.l.johnston@bham.ac.uk
cLaboratoire de Réactivité de Surface, CNRS-Université Pierre et Marie Curie, 4 Place Jussieu, 75005 Paris, France. E-mail: catherine.louis@upmc.fr

Received 2nd August 2015 , Accepted 2nd August 2015
The Recent advances in the chemical physics of nanoalloys themed issue aims at presenting the state-of-the-art of research in nanoalloys. The term nanoalloy is nowadays used with a rather broad meaning, since it is used to indicate all bi- or multi-component nanoparticles that are made of atomic species that are metallic in the bulk. Therefore a nanoalloy can be a very small cluster, containing only a few atoms, or a large nanoparticle with a diameter of a few hundred nanometers. Nanoalloys can present intermixed arrangements of their constituent elements, like in solid solutions and in ordered alloys, or phase-separated arrangements, giving for example core–shell and Janus particles.

In the last decade, there has been a growing interest for research in nanoalloys, which has led to an impressive development of the field, in both experiment and theory/modelling. This growing interest partly stems from the wide variety of potential applications of nanoalloys, for example in catalysis, plasmonics, magnetic data storage, and biomedicine.

At variance with single-component metallic nanoparticles, the properties of nanoalloys can be tuned by varying not only their size but also their composition. This gives a much wider spectrum of possibilities, but, at the same time, poses new challenges for what concerns the controlled growth/synthesis, and the characterization of these systems. These challenges are better addressed by concerted efforts in experiments and modelling.

Experimental techniques involve preparation methods such as gas-phase growth and liquid-phase synthesis, and a variety of characterization tools, including TEM, aberration corrected STEM, X-ray diffraction, X-ray scattering and absorption spectroscopies and UV-vis and IR spectroscopies, temperature programmed desorption analysis and many others that are increasingly being performed in in situ or operando conditions.

Due to the complexity of the energy landscape of nanoalloys, and to the range of different length and time scales involved, modelling of nanoalloys is a challenge in itself, requiring the combination of techniques that range from ab initio electronic structure calculations, to molecular dynamics and Monte Carlo simulations within atomistic models, to coarse-grained methods, and finally to thermodynamic modelling.

The articles contained in this themed issue give a thorough coverage of the most relevant aspects of recent research in nanoalloys. Even though some articles of this collection treat different aspects and properties of a given nanoalloy (for example, structure and magnetism, or synthesis and chemical reactions), we have chosen to classify the contributions according to six different categories: (a) structure and thermodynamics; (b) growth/synthesis; (c) chemical reactions and catalysis; (d) optics and plasmonics; (e) magnetism; and (f) biomedical applications.

(a) Structure and thermodynamics – many articles deal with the experimental characterization and the theoretical prediction of the geometric structure and of the chemical ordering of nanoalloys, including two perspective articles [DOI: 10.1039/C5CP00274E and DOI: 10.1039/C5CP01492A]. Most articles deal with equilibrium aspects, for example with the search of the optimal geometric structures and chemical ordering patterns, or with the study of phase transitions. However there are also some contributions dealing with dynamical aspects, such as vibrations, diffusion or structural evolution from non-equilibrium states. A variety of systems is considered in the collection, such as Fe–Pt [DOI: 10.1039/C5CP00277J], Pd–Au [DOI: 10.1039/C5CP00491H and DOI: 10.1039/C5CP00249D], Cu–Ni [DOI: 10.1039/C5CP00215J], Ag–Au [DOI: 10.1039/C5CP00232J and DOI: 10.1039/C5CP01061F], Ni–Sn [DOI: 10.1039/C5CP00281H], Pt–Ir [DOI: 10.1039/C5CP00497G], Cu–Ag [DOI: 10.1039/C5CP00600G, DOI: 10.1039/C5CP00782H, DOI: 10.1039/C5CP00198F, DOI: 10.1039/C5CP01198A, DOI: 10.1039/C5CP01390A and DOI: 10.1039/C5CP01593F], Pd–Ag [DOI: 10.1039/C5CP00312A], Au–Cu [DOI: 10.1039/C5CP00298B and DOI: 10.1039/C5CP01061F], Co–Pd [DOI: 10.1039/C5CP01029B], Co–Pt [DOI: 10.1039/C5CP01070E], Cu–Pt [DOI: 10.1039/C5CP01096A], and Au–Rh [DOI: 10.1039/C5CP00249D].

(b) Growth/synthesis – the issue of developing better methods for the controlled production of nanoalloys with specific structures and/or properties is considered in several articles. The majority of them deal with liquid-phase synthesis by chemical methods [DOI: 10.1039/C4CP06012A, DOI: 10.1039/C5CP00222B, DOI: 10.1039/C5CP01062D, DOI: 10.1039/C5CP01491C, DOI: 10.1039/C5CP00075K and DOI: 10.1039/C5CP02058A], but physical methods, such as laser ablation in solution [DOI: 10.1039/C5CP00279F], pulsed laser deposition [DOI: 10.1039/C5CP01491C], vapour growth on crystal surfaces [DOI: 10.1039/C5CP00075K], and gas-phase condensation accompanied by mass selection [DOI: 10.1039/C5CP00285K] are well represented. A computational study of the nucleation on surfaces is also present [DOI: 10.1039/C5CP00304K].

(c) Chemical reactions and catalysis – catalysis is a field in which the use of nanoalloys has a long-standing tradition. It is therefore not surprising that several articles of this themed issue deal with chemical reactions on nanoalloys. These comprise oxygen reduction reactions [DOI: 10.1039/C4CP04264F, DOI: 10.1039/C5CP00283D and DOI: 10.1039/C5CP00503E], selective hydrogenation [DOI: 10.1039/C5CP00282F, DOI: 10.1039/C5CP00280J and DOI: 10.1039/C5CP00632E], the oxidation of propene [DOI: 10.1039/C5CP00590F], the reduction of 4-nitrophenol [DOI: 10.1039/C5CP00519A], and CO oxidation [DOI: 10.1039/C5CP00889A]. A simulation of cyclic voltammetry is found in [DOI: 10.1039/C5CP00394F].

(d) Optics and plasmonics – this field has witnessed impressive development in recent times. In this themed issue three contributions can be found: a perspective article [DOI: 10.1039/C5CP00498E], and studies of the use of nanoalloys in boosting the photoluminescence of erbium ions [DOI: 10.1039/C5CP01084E] and of the plasmonic behaviour of noble-metal clusters [DOI: 10.1039/C5CP01177A].

(e) Magnetism – magnetic properties of nanoalloys are widely studied in view of applications in high-density data storage. In this themed issue there are several contributions, including a perspective article [DOI: 10.1039/C5CP00943J], studies of magnetic superatoms [DOI: 10.1039/C4CP03753G], and studies of magnetism in Fe–Au [DOI: 10.1039/C5CP00299K], in Au–Rh [DOI: 10.1039/C5CP00115C], in Co–Rh and Co–Au [DOI: 10.1039/C5CP01923K] and in nanocrystalline alloys [DOI: 10.1039/C5CP00245A].

(f) Biomedicine – biomedical applications of nanoalloys are now emerging. Two perspective articles [DOI: 10.1039/C5CP00831J and DOI: 10.1039/C5CP01219H] deal with this topic.

Finally, we would like to note that a great part of the research contained in this themed issued has been conducted in the framework of a European network supported by the European Cooperation in Science and Technology (COST), specifically in the framework of the COST Action MP0903 NANOALLOY. COST support has allowed the organization of several conferences and workshops on nanoalloys. Support was also provided for exchange visits between laboratories. This support has greatly helped in developing collaborations and in boosting research in the field of nanoalloys in Europe.

This journal is © the Owner Societies 2015