Wavelength-Selective Photocatalysis Using Gold–Platinum Nanorattles

Abstract

The selectivity of a thermal catalyzed reaction with multiple products, catalyzed on the surface of a catalyst exhibiting different surface facets and surface energy, is controlled by the temperature. Manipulating the temperature makes one product more dominant than the other.The selectivity of the photochemical reaction on the surface of plasmonic nanocatalyst of multiple plasmon modes is controlled by changing the wavelength of the exciting light. Gold nanospheres (AuNSs) located inside of gold-platinum double shell nanoparticles in a rattle structure were prepared with different sizes and showed two plasmon spectral modes. The high energy plasmon mode corresponds to the photo-excitation of the small nanosphere, while the low energy plasmonic mode is related to both the gold-platinum double shell plasmon and the inside nanosphere, as assigned by calculation using the discrete dipole approximation (DDA) simulation technique. Photodimerization of 4-nitrothiophenol (4NTP) adsorbed on the surface of gold platinum nanorattles (AuPtNRTs) was studied using the surface-enhanced Raman spectroscopy technique. When the AuPtNRTs are photo-excited at the high energy band at 532 nm, which selectively excites the AuNS, 4NTP is photodimerized into an azo compound only on the surface of AuNS. The 4NTP adsorbed on the surface of the outer gold-platinum double shell did not react. Despite the fact that 785 nm photons excite both the AuNS and the outer shell of the AuPtNRTs, no photodimerization is observed with such low energy photons.

Macroscopic and tunable nanoparticle superlattices

“….. reveals a hexagonal packing of nanoparticles with corresponding diffraction indices (10), (11), (20), (21), (30) and higher-order Bragg reflections.…”

“….. (i = 1-9) revealing the formation of a long-range ordered 2D hexagonal superlattice of AuNPs with an inter-particle distance of a L = 4π/( √ 3Q 1 ) = 322 Å, where the corresponding diffraction peaks are indexed as (10), (11), (20), (21), (30) and higherorder Bragg reflections. This demonstrates that K 2 CO 3 plays a crucial role in promoting interfacial self-assembly and crystallization of PEG 6k -AuNPs.…”

“…[4][5][6][7][8] Concomitantly, two-dimensional (2D) self-assembly of AuNPs at solid-or vapor-liquid interfaces have also been developed, [9][10][11] providing valuable understanding of general mechanisms involved in self-assembly that can be readily applied in other dimensions. Employing a self-and guided-assembly approach, it has been shown that capped AuNPs, AgNPs, or magnetite with various surfactants (including thiolated-acyl chains, -PEG, and others) can be manipulated in a Langmuir trough to form ordered 2D domains, which can be transferred to solid support by the Langmuir-Blodgett technique for further applications [12][13][14][15][16][17][18][19][20][21] . Recently, it has been shown that unpaired thiolated ssDNA functionalized AuNPs (ssDNA-AuNPs) self-assemble and crystallize at gas-solution interfaces spontaneously simply by tuning various salts concentrations.…”

Controlling Reaction Selectivity over Hybrid Plasmonic Nanocatalysts

“…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 nanocatalysis. 49−52 Therefore, here we focus on multimetallic 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 application.…”

Electrochemical top-down synthesis of C-supported Pt nano-particles with controllable shape and size: Mechanistic insights and application

“…Currently, most of the state-of-the-art synthetic procedures in nanochemistry are based on colloidal wet-chemical "bottom up" approaches, which often require complex steps. In most cases the shape of the nanoparticle is controlled by surfactants [10][11][12] or by predefined templates [13]. Such surface capping agents often decrease the activity of metal nanoparticles in heterogeneous catalysis, thus requiring additional steps for removal of the surfactants from the resulting species.…”