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Controlling Reaction Selectivity over Hybrid Plasmonic Nanocatalysts Jhon Quiroz, Eduardo Cesar Melo Barbosa, Thaylan P Araujo, Jhonatan Luiz Fiorio, Yichi Wang, Yichao Zou, Tong Mou, Tiago Vinicius Alves, Daniela C de Oliveira, Bin Wang, Sarah J. Haigh, Liane Marcia Rossi, and Pedro HC Camargo Nano Lett., Just Accepted Manuscript • DOI: 10.1021/acs.nanolett.8b03499 • Publication Date (Web): 23 Oct 2018 Downloaded from http://pubs.acs.org on October 24, 2018
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Nano Letters
Controlling Reaction Selectivity over Hybrid Plasmonic Nanocatalysts
Jhon Quiroz,a Eduardo C. M. Barbosa,a Thaylan P. Araujo,a Jhonatan L. Fiorio,a Yi-Chi Wang,b Yi-Chao Zou, b Tong Mou,c Tiago V. Alves,d Daniela C. de Oliveira,e Bin Wang,c Sarah J. Haigh,b Liane M. Rossi,a and Pedro H. C. Camargoa,*
a
Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo,
Av. Prof. Lineu Prestes, 748, 05508-000 São Paulo, SP, Brazil b School
of Materials, University of Manchester, Manchester, M13 9PL, UK
c Center
for Interfacial Reaction Engineering and School of Chemical, Biological, and
Materials Engineering, Gallogly College of Engineering, The University of Oklahoma, Norman, OK, USA d Departamento
de Físico-Química, Instituto de Química, Universidade Federal da Bahia
Rua Barão de Jeremoabo, 147, 40170-115, Salvador-BA, Brazil e Centro
Nacional de Pesquisa em Energia e Materiais, Laboratório Nacional de Luz
Síncrotron, 13083-970, Campinas, SP, Brasil
*Corresponding author: Email:
[email protected] 1 ACS Paragon Plus Environment
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Abstract
The localized surface plasmon resonance (LSPR) excitation in plasmonic nanoparticles has been used to accelerate several catalytic transformations under visible-light irradiation. In order to fully harness the potential of plasmonic catalysis, multimetallic nanoparticles containing a plasmonic and a catalytic component, where LSPR-excited energetic charge carriers and the intrinsic catalytic active sites work synergistically, have raised increased attention. Despite several exciting studies observing rate enhancements, controlling reaction selectivity remains very challenging. Here, by employing multimetallic nanoparticles combining Au, Ag and Pt in an Au@Ag@Pt core-shell and an Au@AgPt nanorattle architectures, we demonstrate that reaction selectivity of a sequential reaction can be controlled under visible light illumination. The control of the reaction selectivity in plasmonic catalysis was demonstrated for the hydrogenation of phenylacetylene as a model transformation. We have found that the localized interaction between the triple bond in phenylacetylene and the Pt nanoparticle surface enables selective hydrogenation of the triple bond (relative to the double bond in styrene) under visible light illumination. Atomistic calculations show that the enhanced selectivity toward the partial hydrogenation product is driven by distinct adsorption configurations and charge delocalization of the reactant and the reaction intermediate at the catalyst surface. We believe these results will contribute to the use of plasmonic catalysis to drive and control a wealth of selective molecular transformations under eco-friendly conditions and visible light illumination.
Keywords: plasmonic catalysis, nanorattles, platinum, selectivity, visible light, hydrogenation
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Nano Letters
Plasmonic nanoparticles have emerged as attractive systems to efficiently harvest solar energy in order to drive and control chemical transformations.1–4 In plasmonic nanoparticles, incident photons resonantly interact with the collective motion of electrons, a phenomenon known as localized surface plasmon resonance (LSPR).5,6 It has been shown the LSPR excitation of nanocatalysts can enhance the rates of several chemical transformations, a phenomena referred to as plasmonic nanocatalysis.7–10 Studies on plasmonic nanocatalysis generally focus on nanoparticles supporting LSPR excitation in the visible and near-infrared ranges, such as gold (Au),11–14 silver (Ag),15,16 and copper (Cu).17 However, the catalytic properties of these systems are limited. Conversely, several metals that are important for nanocatalysis do not display LSPR excitation in the visible or near-infrared ranges.18,19 In this context, multimetallic nanoparticles containing a plasmonic and a catalytic component represents a remarkable opportunity to marry plasmonic and catalytic properties.20,21,30,22–29 The LSPR excitation involves generation of strong electromagnetic fields localized around plasmonic nanoparticles that decay either via the radiative scattering of photons or non-radiatively by the formation of energetic charge carriers (hot electrons and holes).31,32 These hot carriers can flow to the surface of the nanoparticle, where they can be injected into the molecular orbitals of adsorbates or metal-adsorbate complexes, activating these species and enabling increased reaction rates.7,8,33,34 In addition, this opens the possibility for controlling the reaction selectivity as the injection of these hot carriers to specific molecular orbitals of adsorbates or metal-adsorbate complex can be maneuvered.17,35–40 Nonetheless, despite several studies of rate enhancements and mechanisms8,14,22,41,42, achieving control over reaction selectivity in plasmonic nanocatalysis remains challenging. In order to provide insights into reaction selectivity in plasmonic nanocatalysis, we engineered multimetallic plasmonic-catalytic architectures composed of Au, Ag and Pt. In 3 ACS Paragon Plus Environment
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these systems, we investigated the effect of distinct surface interactions between the substrate and the metal surface, which enable different bond activation pathways for tunable product formation under LSPR excitation. We employed the catalytic hydrogenation of phenylacetylene as a model transformation and multimetallic core-shell and nanorattle architectures as plasmonic catalysts to selectively produce styrene - an important precursor for polystyrene and several copolymers. Our results demonstrated that the preferential bond interaction between the C-C triple bond and Pt at the surface of our catalysts enabled control of reaction selectivity, in which an increase towards the formation of styrene, the semihydrogenation product, was observed under visible light. The proper choice of nanomaterials compositions and architectures that enables one to combine plasmonic and catalytic properties and is fundamental for producing versatile plasmonic nanocatalysts with high activity and the potential for the understanding and control of reaction selectivity.43–46 It has been recently postulated that core-shell nanoparticles containing a plasmonic core surrounded by a very thin shell of a catalytic nanoparticle provides an interesting scenario towards enabling the intensification of plasmon-driven catalytic reactions in catalytic metals that do not support SPR excitation in the visible and near-infrared ranges.22,47 In addition to these core-shell systems, our group recently demonstrated that plasmon hybridization in multimetallic and plasmonic nanorattles (comprised of an Au sphere inside a AgAu shell, for example) can achieve superior plasmonic catalytic activities relative to nanosphere and nanoshell counterparts. This was observed as a result of plasmon hybridization, that leads to higher E-field enhancements relative to individual nanostructures as a result of LSPR excitation,48 indicating that the nanorattle morphology may be promising in terms of activity enhancements and possibly selectivity assessment in plasmonic nanocatalysis49–52. Therefore, here we focus on multimetallic 4 ACS Paragon Plus Environment
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Nano Letters
nanorattles as a target architecture. For our elements of interest, we chose to exploit the well-known plasmonic properties of Au and Ag to enhance and control catalytic transformations at the surface of Pt, an excellent catalytic metal with widespread application53. We first modelled the optical properties of plasmonic nanorattles comprised of a Au nanosphere inside a Pt shell. Figure S1 depicts the electric field enhancement contours calculated by the discrete dipole approximation (DDA) method for Au@Pt nanorattles (Figure S1A and B), as well as the Au nanospheres (Figure S1C) and Pt shells (Figure S1D) counterparts. The Au@Pt nanorattles were 63 nm in outer diameter, 5 nm in shell thickness, and contained a 37 nm Au nanosphere inside its core. The Au nanospheres were 37 nm in diameter, and the Pt nanoshells 63 nm in outer diameter and 5 nm in shell thickness. Considering a light excitation wavelength matching the maximum in the calculated LSPR extinction spectra (Figure S2), the electric field enhancements were significantly higher for the nanorattles relative to the Au nanosphere when the nanorattle was excited at 713 nm. This can be assigned to the hybridization between the core and shell components, in agreement with this observation the calculated extinction spectrum for the Au@Pt nanorattles displayed two bands centered at 481 and 713 nm. Figure S3 shows the contributions from absorption and scattering to the extinction in the Au@Pt nanorattles. These simulations indicate that the presence of a Pt shell in the nanorattles leads to strong absorption as opposed to scattering. This indicates that absorption represents the dominant LSPR decay pathway in the nanorattles. This partitioning of energy between absorption and scattering is beneficial in the context of plasmonic nanocatalysis, as absorption is directly responsible for the generation of hot carriers. Thus, stronger absorption would result in the
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efficient formation of LSPR-excited charge carriers that can be transferred at the metalmolecule interface and contribute to plasmonic-catalytic performances. For experimental verification of the modelling results, we wanted to investigate both multimetallic nanorattles and their equivalent multimetallic core-shell nanoparticles. Both architectures comprise of a plasmonic core and a shell containing the catalytic material (Pt) allowing us to systematically investigate the role of the nanorattle relative to the core-shell morphology. To achieve this, we designed a synthetic approach that allowed us to obtain both plasmonic nanorattles containing a Au core and a Pt-based shell, and core-shell analogues in which a thin Pt shell is present at the surface of a plasmonic core. Our strategy was based on a combination of seeded growth followed by galvanic replacement as illustrated in Figure 1A (see supporting information for details). Firstly, Au nanoparticles 30 nm in diameter were employed as physical templates for the Ag deposition at their surface, leading to Au@Ag coreshell nanoparticles. Then, the Au@Ag core-shell nanoparticles were employed as chemical templates in a galvanic replacement reaction with PtCl62-. In this case, simply by changing the concentration of PtCl62- employed in the synthesis, the final morphology of the material can be precisely maneuvered. When 0.1 mM PtCl62- was employed, the deposition of a thin Pt shell at the Au@Ag surface takes place, generating Au@Ag@Pt core-shell nanoparticles. Conversely, if 0.2 mM PtCl62- is employed, Au@AgPt nanorattles are obtained. Figure 1B-E shows high resolution electron microscopy (HRTEM) and scanning transmission electron microscope (STEM) high angle annular dark field (HAADF) images for multimetallic Au@Ag@Pt core-shell nanoparticles (Figure 1B and C) and Au@AgPt nanorattles (Figure 1D and E). The STEM-HAADF image of the Au@Ag@Pt (Figure 1C) clearly shows the difference in atomic number contrast between the Au core and the Ag shell. In this case, the Au nanoparticles (NPs) were 32 nm in diameter, and the Ag shell thickness corresponded to 6 ACS Paragon Plus Environment
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Nano Letters
35nm. The presence of an ultrathin Pt shell
