Synthesis of Ternary and Quaternary Au and Pt Decorated CdSe/CdS Heteronanoplatelets with Controllable Morphology

Abstract

1 of 11) 1604685 separation, the mixing of electronic states, and how synergistic properties of metals and the semiconductors occur in the same particle. [1b,2] The great advantage of ultrafast electron transfer and charge carrier (electron-hole) separation at the metalsemiconductor interface has motivated researchers to discuss applications in, e.g., photocatalytic water splitting, [3] pollutant degradation, [4] field effect transistors, [5] CO 2 reduction reactions, [6] etc. The metal-decorated nanostructures are also employed for self-assembling in solutions or on substrates to measure their electrical transport properties. [7] Various synthetic approaches (such as reduction, thermal annealing, photoinduced reactions, nanowelding, and many others) have enabled scientists to produce nanoheteroparticles with many possible combinations of metals (e.g., Au, Pt, Pd, Ni, or Co) and different shapes of metal-chalcogenide semiconductors, starting from spherical dots, [2a,3b,4c,8] nanorods, [1b,2b,9] nanowires, [9a] tetrapods, [1b,10] and pyramids, [11] to cubes [4b,12] and many more. [9g,13] In some cases, selective deposition of the metal domains (Au, Pt, Ag, Ni, Co, or Cu) at one end or both ends of the nanorods, at the tips of tetrapods, or only at the sides of rod-shaped semiconductor domains are shown in literature. [2a,9b,14] A variety of new ternary and quaternary metal-semiconductor inorganic nanostructures with unprecedented structural morphologies is achieved by the decoration of five monolayer-thick CdSe/CdS core/crown nanoplatelets with Au and Pt domains. Significant differences in metal growth behavior are observed by varying the CdSe core and the CdS crown dimensions. Depending on the core size, Au growth can be directed only to the CdS edges, or both at the edges and at the center of the nanoplatelets. In contrast, the nucleation of Pt domains always happens at the CdS edges independently of the core and crown dimensions. Furthermore, quaternary structures are obtained by additional Au growth on Pt-decorated CdSe/CdS nanoplatelets, where the effect of steric hindrance of the existing Pt domains results in the Au nucleation to occur only at the CdSe core. Instead, a change in the order of growth of the two noble metals results in Pt-Au alloys present only at the surrounding edges of the nanoplatelets. Additionally, the metal-decorated nanoplatelets are found to be efficient catalysts for H 2 fuel generation under white light irradiation. The highest apparent quantum efficiency measured is 19.3% ± 1.4% with a turnover frequency of ≈10 5 molecules of H 2 per hour per nanoplatelet.

Chemoselective Surface Trap-Mediated Metal Growth on Semiconductor Nanocrystals

“…If more Au was deposited by extending the precursor addition to 20 min or more, heterogeneous nucleation of Au elsewhere on the CdS surface occurred as well. The different particle shapes for Pt and Au are in accordance with the observations made by Naskar et al for nanoplatelet seeds, , excluding the preference for heavier chalcogenides, since CdTe was not investigated in these works. There exist three differences between Pt and Au growth: the higher reactivity of the HAuCl 4 precursor (indicated by the much lower reaction temperature), its higher reduction potential (see Scheme A), and the presence of Cl – ions, which are known to affect Cd chalcogenide surfaces .…”

Region-Controlled Framework Interface Mediated Anion Exchange Chemical Transformation to Designed Metal Phosphosulfide Heteronanostructures

“…Figure a demonstrates the schematic illustration of the morphological and structural evolution for P and S anion exchange processes mediated by the edge-controlled growth of Co 2 P with a middle amount (3.6 mg) of the cobalt precursor. Figure b shows Co 2 P domains located at the edges of Cu 1.81 S NPls, similar to the previously reported Cu 2– x S@Ru nanocages, forming a core–dotted morphology, which was due to the relatively more active edges than the basal surfaces . As the reaction continued, the desulfurizing effect of TPOP induced P anion exchange mainly from the top and bottom surface due to their less protection compared to the edge physical barriers, so the plate thickness in the central region rapidly decreased as mentioned above (Figure c,d).…”

Spectroelectrochemical Investigation of the Charge Carrier Kinetics of Gold‐Decorated Cadmium Chalcogenide Nanorods

“…The absorption spectra of gold decorated CdSe/CdS NRs was measured in an integration sphere to eliminate the effect of scattering at higher wavelengths. Comparable absorption spectra for metal decorated metalchalcogenide nanoparticles have been found in literature ,,. ITO itself absorbs photons in the UV/Vis regime (see Supporting Information Figure SI‐7).…”