Approaches to modelling the shape of nanocrystals.

Unlike in the bulk, at the nanoscale shape dictates properties. The imperative to understand and predict nanocrystal shape led to the development, over several decades, of a large number of mathematical models and, later, their software implementations. In this review, the various mathematical approaches used to model crystal shapes are first overviewed, from the century-old Wulff construction to the year-old (2020) approach to describe supported twinned nanocrystals, together with a discussion and disambiguation of the terminology. Then, the multitude of published software implementations of these Wulff-based shape models are described in detail, describing their technical aspects, advantages and limitations. Finally, a discussion of the scientific applications of shape models to either predict shape or use shape to deduce thermodynamic and/or kinetic parameters is offered, followed by a conclusion. This review provides a guide for scientists looking to model crystal shape in a field where ever-increasingly complex crystal shapes and compositions are required to fulfil the exciting promises of nanotechnology

Wulff-Based Approach to Modeling the Plasmonic Response of Single Crystal, Twinned, and Core-Shell Nanoparticles.

The growing interest in plasmonic nanoparticles and their increasingly diverse applications is fuelled by the ability to tune properties via shape control, promoting intense experimental and theoretical research. Such shapes are dominated by geometries that can be described by the kinetic Wulff construction such as octahedra, thin triangular platelets, bipyramids, and decahedra, to name a few. Shape is critical in dictating the optical properties of these nanoparticles, in particular their localized surface plasmon resonance behavior, which can be modeled numerically. One challenge of the various available computational techniques is the representation of the nanoparticle shape. Specifically, in the discrete dipole approximation, a particle is represented by discretizing space via an array of uniformly distributed points-dipoles; this can be difficult to construct for complex shapes including those with multiple crystallographic facets, twins, and core-shell particles. Here, we describe a standalone user-friendly graphical user interface (GUI) that uses both kinetic and thermodynamic Wulff constructions to generate a dipole array for complex shapes, as well as the necessary input files for DDSCAT-based numerical approaches. Examples of the use of this GUI are described through three case studies spanning different shapes, compositions, and shell thicknesses. Key advances offered by this approach, in addition to simplicity, are the ability to create crystallographically correct structures and the addition of a conformal shell on complex shapes

On the identification of twinning in body-centred cubic nanoparticles

Many metals and alloys, including Fe and W, adopt body-centred cubic (BCC) crystal structures and nanoparticles of these metals are gaining significant scientific and industrial relevance. Twinning has a marked effect on catalytic activity, yet there is little evidence for or against the presence of twinning in BCC nanoparticles. Here, we explore the potential shapes of twinned BCC nanoparticles, and predict their electron microscopy and diffraction signatures. BCC single crystal and twinned shapes often appear similar and diffraction patterns along common, low-index zone axes are often indistinguishable, casting doubt on many claims of single crystallinity. We conclude by outlining how nanoparticles can be characterized to conclusively prove the presence or absence of twinning

Size Control in the Colloidal Synthesis of Plasmonic Magnesium Nanoparticles.

Nanoparticles of plasmonic materials can sustain oscillations of their free electron density, called localized surface plasmon resonances (LSPRs), giving them a broad range of potential applications. Mg is an earth-abundant plasmonic material attracting growing attention owing to its ability to sustain LSPRs across the ultraviolet, visible, and near-infrared wavelength range. Tuning the LSPR frequency of plasmonic nanoparticles requires precise control over their size and shape; for Mg, this control has previously been achieved using top-down fabrication or gas-phase methods, but these are slow and expensive. Here, we systematically probe the effects of reaction parameters on the nucleation and growth of Mg nanoparticles using a facile and inexpensive colloidal synthesis. Small NPs of 80 nm were synthesized using a low reaction time of 1 min and ∼100 nm NPs were synthesized by decreasing the overall reaction concentration, replacing the naphthalene electron carrier with biphenyl or using metal salt additives of FeCl3 or NiCl2 at longer reaction times of 17 h. Intermediate sizes up to 400 nm were further selected via the overall reaction concentration or using other metal salt additives with different reduction potentials. Significantly larger particles of over a micrometer were produced by reducing the reaction temperature and, thus, the nucleation rate. We showed that increasing the solvent coordination reduced Mg NP sizes, while scaling up the reaction reduced the mixing efficiency and produced larger NPs. Surprisingly, varying the relative amounts of Mg precursor and electron carrier had little impact on the final NP sizes. These results pave the way for the large-scale use of Mg as a low-cost and sustainable plasmonic material.Support for this project was provided by the EU Framework Programme for Research and Innovation Horizon 2020 (ERC Starting Grant SPECs 804523). E.R.H. is thankful for funding from the EPSRC NanoDTC Cambridge (EP/L015978/1). J.A. acknowledges financial support from Natural Sciences and Engineering Research Council of Canada and Fonds de Recherche du Québec–Nature et Technologies postdoctoral fellowships (BP and B3X programs). C.B. is thankful for funding from the Engineering and Physical Sciences Research Council (Standard Research Studentship (DTP) EP/R513180/1). B.P. and L.T.M. acknowledge support from UK Engineering and Physical Science and Research Council (grant number EP/L020443/2). Thanks to Giulio I. Lampronti for helpful discussions and support

Decoration of plasmonic Mg nanoparticles by partial galvanic replacement.

Plasmonic structures have attracted much interest in science and engineering disciplines, exploring a myriad of potential applications owing to their strong light-matter interactions. Recently, the plasmonic concentration of energy in subwavelength volumes has been used to initiate chemical reactions, for instance by combining plasmonic materials with catalytic metals. In this work, we demonstrate that plasmonic nanoparticles of earth-abundant Mg can undergo galvanic replacement in a nonaqueous solvent to produce decorated structures. This method yields bimetallic architectures where partially oxidized 200-300 nm Mg nanoplates and nanorods support many smaller Au, Ag, Pd, or Fe nanoparticles, with potential for a stepwise process introducing multiple decoration compositions on a single Mg particle. We investigated this mechanism by electron-beam imaging and local composition mapping with energy-dispersive X-ray spectroscopy as well as, at the ensemble level, by inductively coupled plasma mass spectrometry. High-resolution scanning transmission electron microscopy further supported the bimetallic nature of the particles and provided details of the interface geometry, which includes a Mg oxide separation layer between Mg and the other metal. Depending on the composition of the metallic decorations, strong plasmonic optical signals characteristic of plasmon resonances were observed in the bulk with ultraviolet-visible spectrometry and at the single particle level with darkfield scattering. These novel bimetallic and multimetallic designs open up an exciting array of applications where one or multiple plasmonic structures could interact in the near-field of earth-abundant Mg and couple with catalytic nanoparticles for applications in sensing and plasmon-assisted catalysis.Support for this project was provided by the EU Framework Programme for Research and Innovation Horizon 2020 (Starting Grant SPECs 804523). J.A. wishes to acknowledge financial support from Natural Sciences and Engineering Research Council of Canada and “Fonds de Recherche Québec – Nature et Technologies” postdoctoral fellowships (BP and B3X programs). C.B. is thankful for funding from the Engineering and Physical Sciences Research Council (Standard Research Studentship (DTP) EP/R513180/1), and E.R.H. for support from the EPSRC NanoDTC Cambridge (EP/L015978/1). S.M.C. acknowledges support from the Henslow Research Fellowship at Girton College, Cambridge. We acknowledge access and support in the use of the electron Physical Sciences Imaging Centre (MG21980) at the Diamond Light Source, U.K

Facet- and Gas-Dependent Reshaping of Au Nanoplates by Plasma Treatment.

The reshaping of metal nanocrystals on substrates is usually realized by pulsed laser irradiation or ion-beam milling with complex procedures. In this work, we demonstrate a simple method for reshaping immobilized Au nanoplates through plasma treatment. Au nanoplates can be reshaped gradually with nearly periodic right pyramid arrays formed on the surface of the nanoplates. The gaseous environment in the plasma-treatment system plays a significant role in the reshaping process with only nitrogen-containing environments leading to reshaping. The reshaping phenomenon is facet-dependent, with right pyramids formed only on the exposed {111} facets of the Au nanoplates. The morphological change of the Au nanoplates induced by the plasma treatment leads to large plasmon peak redshifts. The reshaped Au nanoplates possess slightly higher refractive index sensitivities and largely increased surface-enhanced Raman scattering intensities compared to the flat, untreated nanoplates. Our results offer insights for studying the interaction mechanism between plasma and the different facets of noble metal nanocrystals and an approach for reshaping light-interacting noble metal nanocrystals

Towards sustainable plasmonics: a study on the shapes and plasmonic properties of magnesium nanoparticles

The growing interest in nanoparticles and their increasingly diverse applications is fuelled by the ability to tune properties via material selection and shape control, promoting intense experimental and theoretical research. For plasmonics, where nanostructures are exploited to focus and channel light in the nanoscale, material and structure effects are studied in relation to optical properties. Understanding such light-matter interactions can inspire the design and synthesis of nanoparticles tailored for various applications, such as in sensing, photocatalysis and biomedicine, to name a few. Modelling shape effects can accelerate this progress and relies on coupling the nanoparticle’s, crystallographically dependent, geometrical representation with electromagnetic simulations. Material selection is also critical. Noble metals, which have been the pillars of plasmonics since the nascence of the field, have certain limitations and do not satisfy the sustainability requirements of modern societies, hence triggering intense research into alternative plasmonic materials. The objective of the current research is thus twofold: to provide a platform for user-friendly and crystallographically correct nanoparticle shape modelling, compatible with available electromagnetic simulation tools, and, helped by this tool, to investigate the shapes and structure-plasmonic property relations for nanoparticles made out of magnesium, a recently introduced plasmonic metal. In this work, the reader is first introduced to the concepts of localised surface plasmon resonances, Wulff-based approaches to nanocrystal shape modelling as well as the challenges and opportunities of magnesium nanoparticles in plasmonics and beyond. The next three chapters focus on nanoparticle shape modelling commencing by a summary of the already available tools. This is followed by the description of Crystal Creator, a GUI developed to facilitate the generation of shape input for electromagnetic simulations and to model the twinned nanoparticle shapes for various crystallographies. The applicability of Crystal Creator on a variety of nanocrystal structures is demonstrated via the calculation of the optical response of well-known face-centred cubic plasmonic metals as well as the investigation of the single crystal and twinned nanoparticle shapes of metals that adopt body-centered cubic and tetragonal crystallographic configurations. The hexagonal close packed adaptation is then used to understand and predict the nanoparticle shapes of magnesium. The two subsequent chapters focus on the plasmonic properties of the modelled magnesium nanoparticles. Here, electromagnetic simulations in the discrete dipole approximation and single-particle dark-field scattering measurements are employed to unravel size, shape and environment effects in the near-field and far-field optical response of the nanoparticles. Finally, a summary and a concluding discussion on the findings of this work, along with an outlook for future research, are provided in the last chapter

Εκτίμηση του βαθμού φυσικής δραστηριότητας σε παιδιά και εφήβους με Σακχαρώδη διαβήτη τύπου 1

Εισαγωγή: Η σωματική άσκηση και η υγιεινή διατροφή, παράλληλα με τον τακτικό αυτοέλεγχο του σακχάρου αίματος είναι οι κύριοι πυλώνες για την επίτευξη της άριστης διαβητικής ρύθμισης στους ασθενείς με ΣΔ τύπου 1. Σκοποί: Ο κύριος σκοπός της παρούσας μελέτης ήταν η διερεύνηση της συχνότητας, του βαθμού και του είδους της φυσικής δραστηριότητας σε παιδιά και εφήβους με ΣΔ τύπου 1. Επιπρόσθετα, τέθηκαν δευτερεύοντες σκοποί, όπως η διερεύνηση της επίδρασης της άσκησης στη σωματική σύσταση, τη διαβητική ρύθμιση, το λιπιδαιμικό προφιλ, στο καρδιαγγειακό σύστημα, και στην εμφάνιση των επιπλοκών του ΣΔ τύπου 1. Επίσης διερευνήθηκαν οι επιπλέον παράγοντες που επηρεάζουν τη σωματική σύσταση και το λιπιδαιμικό προφίλ των ασθενών με ΣΔ τύπου 1, όπως οι διατροφικές συνήθειες και οι δραστηριότητες κατά τον ελεύθερο χρόνο τους (hobbies). Τέλος, μελετήθηκε η συχνότητα και σοβαρότητα των επιπλοκών της άσκησης π.χ η παρουσία υπογλυκαιμικών επεισοδίων. Υλικό και Μέθοδοι: Στη συγκεκριμένη μελέτη έλαβαν μέρος τελικά 79 παιδιά και έφηβοι με ΣΔ τύπου 1, μέσης± SD ηλικίας 14.1±3.98 ετών (εύρος: 6-20 έτη) και διάρκειας νόσου 5.76±4.1 έτη (εύρος: 0.5-16 έτη), οι οποίοι παρακολουθούνται στο Διαβητολογικό Ιατρείο της Β’ Παιδιατρικής Κλινικής του Πανεπιστημίου Αθηνών, του Γ.Ν. Παίδων «Π.&Α. Κυριακού». Αρχικά πραγματοποιούνταν για κάθε ασθενή μετρήσεις των σωματομετρικών του στοιχείων (ύψους και βάρους σώματος) και της αρτηριακής πίεσης και υπολογίσθηκαν ο ΒΜΙ, το BMI-z-score, οι εκατοστιαίες θέσεις της αρτηριακής πίεσης, καθώς και το ποσοστό λιπώδους/μυϊκής μάζας % με την ζυγαριά βιοηλεκτρικής εμπεδομέτρησης. Στη συνέχεια οι ασθενείς απαντούσαν σε ειδικά ανώνυμα ερωτηματολόγια, τα οποία αποτελούσαν τα εργαλεία συλλογής δεδομένων της μελέτης. Συγκεκριμένα το ερωτηματολόγιο αποτελούνταν από τέσσερεις ενότητες: 1. Δημογραφικά στοιχεία, 2. Φυσική Δραστηριότητα, 3. Διατροφικές Συνήθειες, 4. Συμμετοχή σε δραστηριότητες ελευθέρου χρόνου (hobbies). Αποτελέσματα: Από το σύνολο των ασθενών της μελέτης, 29/79 (36.7%) συμμετείχαν συστηματικά σε αθλητικούς συλλόγους, ενώ από τους υπόλοιπους ασθενείς 50/79 (63.29%) δεν έκαναν συστηματική άσκηση. Οι δύο ανωτέρω ομάδες ασθενών χρησιμοποιήθηκαν για τη στατιστική ανάλυση. Διερευνώντας την επίδραση της άσκησης στη σωματική σύσταση των συστηματικά αθλουμένων και μη αθλουμένων ασθενών της μελέτης μας, διαπιστώσαμε ότι οι δύο ανωτέρω ομάδες δεν διέφεραν σημαντικά ως προς τα σωματομετρικά στοιχεία, με εξαίρεση την ομάδα των συστηματικά αθλούμενων εφήβων, οι οποίοι παρουσίασαν σημαντικά χαμηλότερο βάρος σώματος, χαμηλότερο ΒΜΙ, αλλά παρόμοιο BMI-z-score και χαμηλότερη μυϊκή μάζα (%) από τους μη αθλούμενους εφήβους. Οι περισσότερες στατιστικά σημαντικές διαφορές διαπιστώθηκαν στην ομάδα των συστηματικά αθλούμενων εφηβικών κοριτσιών, οι οποίες παρουσίαζαν σημαντικά χαμηλότερο βάρος σώματος (p<0.014), χαμηλότερο ΒΜΙ (p<0.009), αλλά παρόμοιο BMI-z-score και χαμηλότερο % ποσοστό λιπώδους μάζας συγκριτικά με τις μη αθλούμενες (22.9% vs 28.6%, p<0.009 αντίστοιχα). Όσον αφορά στις παραμέτρους της διαβητικής ρύθμισης, μεταξύ των συστηματικά αθλουμένων και μη αθλουμένων ασθενών στο σύνολό τους δεν διαπιστώθηκε διαφορά ως προς την HbA1c ή την ημερησία δόση ινσουλίνης. Μόνο στην ομάδα των συστηματικά αθλούμενων εφηβικών αγοριών διαπιστώθηκε αυξημένη ευαισθησία στην ινσουλίνη συγκριτικά με τα μη αθλούμενα (63.5 vs 44.5 mg σακχάρου/μονάδα ινσουλίνης, p=0.035). Aναφορικά με την εμφάνιση ή μη υπογλυκαιμικών επεισοδίων σε σχέση με την άσκηση, διαπιστώθηκε ότι οι συστηματικά αθλούμενοι ασθενείς παρουσίαζαν κυρίως ήπιες και μέτριες, αλλά όχι σοβαρές υπογλυκαιμίες, συγκριτικά με τους μη αθλούμενους. Οι ασθενείς με άριστη ρύθμιση παρουσίαζαν επεισόδια κυρίως ήπιας υπογλυκαιμίας, σε τριπλάσια συχνότητα από εκείνους με μέτρια διαβητική ρύθμιση, ενώ δεν παρουσίαζαν επεισόδια σοβαρής υπογλυκαιμίας (p=0.035). Αναφορικά με την επίδραση της άσκησης στην αρτηριακή πίεση μόνο στα αθλούμενα εφηβικά κορίτσια διαπιστώθηκε σημαντικά χαμηλότερη συστολική πίεση συγκριτικά με τα μη αθλούμενα (32.25% vs 55.81%, p=0.026). Επίσης στο σύνολο των ασθενών η παρουσία συστηματικής άσκησης συσχετιζόταν σημαντικά με την απουσία δυσλιπιδαιμίας (x2=3.68, p=0.049). Από τα αποτελέσματα της μελέτης μας διαπιστώθηκε ότι υγιεινή διατροφή ακολουθούσαν περίπου οι μισοί ασθενείς της μελέτης μας (58.6%) και ανθυγιεινή διατροφή το 1/5 (16.5%), ενώ η πλειοψηφία (92.4%) των ασθενών ακολουθούσε ωφέλιμα hobbies, και περίπου οι μισοί (62%) μη ωφέλιμα hobbies. Η συστηματική άσκηση δεν σχετιζόταν απαραίτητα με την παρουσία υγιεινής διατροφής και ωφέλιμων hobbies, όμως η παρουσία μη ωφελίμων hobbies ήταν λιγότερο συχνή στους αθλούμενους ασθενείς. H ανθυγιεινή διατροφή και η ενασχόληση με βιντεοπαιχνίδια διαπιστώθηκε ότι συμβάλλουν στην εμφάνιση παχυσαρκίας και πτωχής διαβητικής ρύθμισης σε παιδιά και εφήβους με ΣΔ τύπου 1. Είναι αξιοσημείωτο ότι κανένας από τους αθλούμενους ασθενείς δεν κάπνιζε, ενώ λήψη αλκοόλ παρατηρήθηκε σε πολύ μικρό ποσοστό των ασθενών (6%). Το υψηλό μορφωτικό επίπεδο των γονέων συνέβαλε σημαντικά στον τρόπο προσέγγισης και αντιμετώπισης του ΣΔ τύπου 1 των παιδιών τους με την υιοθέτηση συστηματικής άσκησης, υγιεινής διατροφής και ωφέλιμων hobbies. Συμπεράσματα: Από τους ασθενείς της μελέτης μας διαπιστώθηκε ότι συστηματική άσκηση των ακολουθούσε ένα σημαντικό ποσοστό (36.7%), η οποία σε συνδυασμό με την υγιεινή διατροφή και την αποφυγή των μη ωφέλιμων hobbies, διαδραματίζει σπουδαίο ρόλο για την βέλτιστη αντιμετώπιση της νόσου. Η συστηματική άσκηση συνέβαλε στη βελτίωση της σωματικής σύστασης, της αρτηριακής πίεσης και του λιπιδαιμικού προφίλ των ασθενών, ενώ ο φόβος της υπογλυκαιμίας δεν στάθηκε εμπόδιο στην ενασχόλησή τους με τις φυσικές τους δραστηριότητες. Τέλος ο ρόλος του μορφωτικού επιπέδου των γονέων είναι καθοριστικός για την σωστή προσέγγιση της νόσου, όσον αφορά την υιοθέτηση άσκησης, υγιεινής διατροφής και την αποφυγή των βλαβερών συνηθειών, που οδηγούν στην παχυσαρκία και τη μεταβολική απορρύθμιση.Introduction: Physical exercise and healthy eating, along with regular self-control of blood sugar are the main pillars for the achievement of optimal diabetic control in patients with type 1 diabetes (type 1 DM). Aims: The main purpose of this study was to investigate the frequency, the degree and type of physical activity in children and adolescents with type 1 DM. Additionally, secondary goals, such as the assessment of the effect of exercise on body composition, diabetic control, lipidemic profile, cardiovascular system and on the occurrence of diabetes complications, were set. Additional factors influencing the patients’ body composition and lipidemic profile, such as dietary habits and extracurricular activities (hobbies), were also investigated. Finally, the frequency and severity of the acute complications of exercise, i.e. hypoglycemic episodes, were studied. Materials and methods: This study included 79 children and adolescents with type 1 DM, aged (mean ± SD) 14.1±3.98 years (range: 6-20 years) with a diabetes duration of 5.76±4.1 years (range: 0.5-16 years), who were followed at the Diabetic Clinic of the 2nd Department of Pediatrics, University of Athens, "P.&A.Kyriakou" Children’s Hospital, Athens. Initially, measurements of body weight, height and blood pressure were performed for each patient, the BMI-z-scores and blood pressure percentiles were estimated, and fat/muscle mass (%) were calculated using the bioelectric impedance scale. Patients then answered specific anonymous questionnaires, which constituted the data collection tools of the study. In particular, the questionnaire consisted of four modules: 1. Demographic characteristics, 2. Physical Activity, 3. Eating habits, 4. Participation in hobbies. Results: Among the study population, 29/79 (36.7%) patients participated systematically in sports clubs, while the remaining 50 patients (63.29%), did not do any systematic exercise, and the latter two patients’ groups were used for statistical analysis. Investigating the effect of exercise on the body composition of systematically exercising and non-exercising patients of our study, we found that the two groups did not differ significantly in terms of somatometric data, with the exception of the group of systematically exercising adolescents, who showed significantly lower body weight, lower BMI (but similar BMI-z-score) and lower muscle mass (%) than nonexercising teenagers. The most statistically significant differences were found in the group of teenage girls, since the systematically exercising ones had significantly lower body weight (p<0.014), lower BMI (p <0.009), with similar BMI-z-score and lower fat percentage compared to non-exercising ones (22.9% vs 28.6%, p<0.009). Regarding the parameters of diabetic control, no significant difference in terms of the mean-12 month-HbA1c nor the daily insulin dosage was observed between systematically exercising and non-exercising patients as a whole. Only in the group of systematically exercising adolescent boys, insulin sensitivity was higher compared to the non-exercising ones (63.5vs 44.5 mg of blood glucose/IU, p=0.035). Regarding the occurrence of hypoglycaemic episodes in relation to exercise, it was found that the systematically exercising patients had mostly mild and moderate but not severe hypoglycaemic episodes compared to the non-exercising ones. Moreover patients with excellent glycaemic control experienced episodes of mild hypoglycaemia three times more frequently than those with moderate control (p=0.035), while there were no episodes of severe hypoglycaemia. Regarding the effect of exercise on blood pressure, lower systolic pressure was observed only in systematically exercising pubertal girls in comparison with the non-exercising ones (32.25% vs 55.81%, p=0.026). Moreover in the total patients’ group, systematic exercise was associated with the absence of dyslipidemia (x2=3.68, p=0.049). From our study results it was also found that about half of our patients (58.6%) had healthy eating habits, whileunhealthy diet was followed by 1/5 (16.5%). Moreover the majority (92.4%) of patients had beneficial hobbies, and about half (62%) of them non-beneficial hobbies. Systematic exercise was not necessarily related to the presence of healthy diet and beneficial hobbies, but the presence of non-beneficial hobbies was less common among exercising patients. Unhealthy eating habits and video gaming have been found to contribute to the development of obesity and poor diabetic control in children and adolescents with type 1 DM. It is noteworthy that none of the exercising patients smoked, while alcohol use was observed only in a very small percentage of patients (6%). The parental educational level significantly contributed to the treatment approach of their children's diabetes, by adopting systematic exercise, healthy eating habits and beneficial hobbies. Conclusions: Among the children and adolescents with type 1 DM of our study a significant proportion (36.7%) followed systematic exercise, which in combination with healthy eating habits and the avoidance of non-beneficial hobbies seem to play an important role in the best disease management. Systematic exercise contributed to the improvement of the patients’ body composition, blood pressure and lipid profile, while the fear of hypoglycaemia was not an obstacle to their daily activities. Finally, the role of parents' educational level is crucial to the correct approach of the disease in terms of adopting exercise, healthy eating and avoiding harmful habits, leading to obesity and metabolic disregulation

Magnesium Nanoparticles for Surface-Enhanced Raman Scattering and Plasmon-Driven Catalysis.

Publication status: PublishedNanostructures of some metals can sustain localized surface plasmon resonances, collective oscillations of free electrons excited by incident light. This effect results in wavelength-dependent absorption and scattering, enhancement of the incident electric field at the metal surface, and generation of hot carriers as a decay product. The enhanced electric field can be utilized to amplify the spectroscopic signal in surface-enhanced Raman scattering (SERS), while hot carriers can be exploited for catalytic applications. In recent years, cheaper and more earth abundant alternatives to traditional plasmonic Au and Ag have gained growing attention. Here, we demonstrate the ability of plasmonic Mg nanoparticles to enhance Raman scattering and drive chemical transformations upon laser irradiation. The plasmonic properties of Mg nanoparticles are characterized at the bulk and single particle level by optical spectroscopy and scanning transmission electron microscopy coupled with electron energy-loss spectroscopy and supported by numerical simulations. SERS enhancement factors of ∼102 at 532 and 633 nm are obtained using 4-mercaptobenzoic acid and 4-nitrobenzenethiol. Furthermore, the reductive coupling of 4-nitrobenzenethiol to 4,4'-dimercaptoazobenzene is observed on the surface of Mg nanoparticles under 532 nm excitation in the absence of reducing agents, indicating a plasmon-driven catalytic process. Once decorated with Pd, Mg nanostructures display an enhancement factor of 103 along with an increase in the rate of catalytic coupling. The results of this study demonstrate the successful application of plasmonic Mg nanoparticles in sensing and plasmon-enhanced catalysis