Plasmonic catalysis with designer nanoparticles

Catalysis is central to a more sustainable future and a circular economy. If the energy required to drive catalytic processes could be harvested directly from sunlight, the possibility of replacing contemporary processes based on terrestrial fuels by the conversion of light into chemical energy could become a step closer to reality. Plasmonic catalysis is currently at the forefront of photocatalysis, enabling one to overcome the limitations of "classical" wide bandgap semiconductors for solar-driven chemistry. Plasmonic catalysis enables the acceleration and control of a variety of molecular transformations due to the localized surface plasmon resonance (LSPR) excitation. Studies in this area have often focused on the fundamental understanding of plasmonic catalysis and the demonstration of plasmonic catalytic activities towards different reactions. In this feature article, we discuss recent contributions from our group in this field by employing plasmonic nanoparticles (NPs) with controllable features as model systems to gain insights into structure-performance relationships in plasmonic catalysis. We start by discussing the effect of size, shape, and composition in plasmonic NPs over their activities towards LSPR-mediated molecular transformations. Then, we focus on the effect of metal support interactions over activities, reaction selectivity, and reaction pathways. Next, we shift to the control over the structure in hollow NPs and nanorattles. Inspired by the findings from these model systems, we demonstrate a design-driven strategy for the development of plasmonic catalysts based on plasmonic-catalytic multicomponent NPs for two types of molecular transformations: the selective hydrogenation of phenylacetylene and the oxygen evolution reaction. Finally, future directions, challenges, and perspectives in the field of plasmonic catalysis with designer NPs are discussed. We believe that the examples and concepts presented herein may inspire work and progress in plasmonic catalysis encompassing the design of plasmonic multicomponent materials, new strategies to control reaction selectivity, and the unraveling of stability and reaction mechanisms.Peer reviewe

Stochastic Thermodynamics Analysis of Ultrafast AgAu Nanoshell Dynamics in the Nonlinear Response Regime

The understanding of relaxation dynamics of metallic nanoshells is important for a range of nanotechnological applications. In this work, we present a combined experimental-theoretical study of the relaxation dynamics of AgAu nanoshells. This was investigated using ultrafast pump-probe experiments resonant with the surface plasmon of the nanoshells, as well as via atomistic molecular dynamics simulations of relaxation and temperature-jump (DT-jump) processes. Both techniques were then discussed and complemented using a non-equilibrium statistical mechanical model. Data collected at low energies were consistent with our previously reported work and allowed the characterization of intrinsic electron-phonon coupling times (EPCT) and of the overall relaxation dynamics in terms of a two-temperature model. Data at intermediate and higher energies, in turn, showed a nonlinear dependence of EPCT as a function of the pump power, faster relaxation being observed at higher pump energies. In the limit of small DT-jumps, relaxation based on a two-temperature model is recovered, whereas in the limit of large DT-jumps, the relaxation becomes faster with increasing temperature change. The results reported here give insight on the ultrafast dynamics of AgAu nanoshells and might also be applied to other metallic systems, paving the way to the better understanding of relaxation dynamics of nanoparticles in general.<br /

Synthesis, Characterization And Catalytic Potential Of Mgnio2 Nanoparticles Obtained From A Novel [mgni(opba)](n) Center Dot 9nh(2)o Chain

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)We describe herein the synthesis of MgNiO2 nanoparticles employing a new one-dimensional system [MgNi(opba)](n) center dot 9nH(2)O, with opba standing for ortho-phenylenebis(oxamato), as precursor. The MgNiO2 nanoparticles could be obtained after heat-treatment at 800 degrees C for 5 h under air atmosphere, which was responsible for the elimination of water and organic precursor material leading the formation of nanoparticles with average size of 40 +/- 9 nm. To this end, we first described the synthesis of [MgNi(opba)](n) center dot 9nH(2)O chain, which was obtained using a pre-synthetized Na-2[Ni(opba)] center dot 5H(2)O and Mg2+ (molar ratio of 1:1) in aqueous media and then this chain was calcined to produce the desired MgNiO2 nanoparticles. The obtained MgNiO2 nanoparticles showed good catalytic performance towards ethanol decomposition achieving 100% of substrate conversion and producing acetaldehyde (56.8%) and hydrogen (24.8%) as the main gaseous products. Also, carbon based structures of great interest for technological applications, carbon nanotubes and onions were formed as valuable byproducts. Thus, we believe that our reported results may inspire the synthesis of catalysts with improved performances for applications in other gas-phase transformations. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.42121363513641Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq, Brazil)Fundacao de Amparo a Pesquisa do Estado de Minas Gerais (FAPEMIG) [CEX-APQ-02159-12]Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES, Brazil)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Cu2O spheres as an efficient source of catalytic Cu(I) species for performing azide-alkyne click reactions

We report herein the high yield synthesis of Cu2O spheres displaying well-defined shapes and monodisperse sizes that could be employed as the source of highly catalytic active Cu(I) species towards click reactions between several of alkynes and azides to produce a variety of 1,2,3-triazoles under ligand-free and ambient conditions (in an open reactor). The utilization of Cu2O spheres enabled superior performance as compared to a conventional protocol in which CuSO4 is employed in combination with sodium ascorbate as the catalyst system. In addition, the compounds were obtained in synthetically useful yields, and seven of them have not been previously reported. We believe the results reported herein shed new insights into the optimization of activity and versatility of click reactions towards the synthesis of target molecules in environmentally friendly conditions

AN UNDERGRADUATE LEVEL EXPERIMENT ON THE SYNTHESIS OF Au NANOPARTICLES AND THEIR SIZE-DEPENDENT OPTICAL AND CATALYTIC PROPERTIES

The synthesis of gold nanoparticles (Au NPs) 15, 26, and 34 nm in diameter, followed by the investigation of their size-dependent optical and catalytic properties, is described herein as an undergraduate level experiment. The proposed experiment covers concepts on the synthesis, stabilization, and characterization of Au NPs, their size-dependent optical and catalytic properties at the nanoscale, chemical kinetics, and the role of a catalyst. The experiment should be performed by groups of two or three students in three lab sessions of 3 h each and organized as follows: i) synthesis of Au NPs of different sizes and investigation of their optical properties; ii) evaluation of their catalytic activity; and iii) data analysis and discussion. We believe that this activity enables students to integrate these multidisciplinary concepts in a single experiment as well as to become introduced/familiarized with an active research field and current literature in the areas of nanoparticle synthesis and catalysis

Surface Segregated AgAu Tadpole-Shaped Nanoparticles Synthesized Via a Single Step Combined Galvanic and Citrate Reduction Reaction

New AgAu tadpole nanocrystals were synthesized in a one-step reaction involving simultaneous galvanic replacement between Ag nanospheres and AuCl4−(aq.) and AuCl4−(aq.) reduction to Au in the presence of citrate. The AgAu tadpoles display nodular polycrystalline hollow heads, while their undulating tails are single crystals. The unusual morphology suggests an oriented attachment growth mechanism. Remarkably, a 1 nm thick Ag layer was found to segregate so as to cover the entire surface of the tadpoles. By varying the nature of the seeds (Au NPs), double-headed Au tadpoles could also be obtained. The effect of a number of reaction parameters on product morphology were explored, leading to new insights into the growth mechanisms and surface segregation behavior involved in the synthesis of bimetallic and anisotropic nanomaterials

Synthesis, characterization and catalytic potential of MgNiO2 nanoparticles obtained from a novel [MgNi(opba)]n·9nH2O chain

We describe herein the synthesis of MgNiO2 nanoparticles employing a new one-dimensional system [MgNi(opba)](n) center dot 9nH(2)O, with opba standing for ortho-phenylenebis(oxamato), as precursor. The MgNiO2 nanoparticles could be obtained after heat-treatment at 800 degrees C for 5 h under air atmosphere, which was responsible for the elimination of water and organic precursor material leading the formation of nanoparticles with average size of 40 +/- 9 nm. To this end, we first described the synthesis of [MgNi(opba)](n) center dot 9nH(2)O chain, which was obtained using a pre-synthetized Na-2[Ni(opba)] center dot 5H(2)O and Mg2+ (molar ratio of 1:1) in aqueous media and then this chain was calcined to produce the desired MgNiO2 nanoparticles. The obtained MgNiO2 nanoparticles showed good catalytic performance towards ethanol decomposition achieving 100% of substrate conversion and producing acetaldehyde (56.8%) and hydrogen (24.8%) as the main gaseous products. Also, carbon based structures of great interest for technological applications, carbon nanotubes and onions were formed as valuable byproducts. Thus, we believe that our reported results may inspire the synthesis of catalysts with improved performances for applications in other gas-phase transformations42121363513641CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE MINAS GERAIS - FAPEMIGsem informaçã