High-index faceted Au nanocrystals with highly controllable optical properties and electro-catalytic activity

Abstract

We introduce a new and naturally abundant mild reducing agent, tannic acid, to improve the seed-mediated growth method for the synthesis of elongated tetrahexahedral Au nanocrystals enclosed with high-index (730) planes, at room-temperature. The control of the dimensions, plasmonics and electro-catalysis of such high-index faceted nanocrystals is remarkable.

Facile Synthesis of Concave Cuboid Au NCs with Precisely Tunable Dimensions and Mechanistic Insight

“…When 1:1 ratio of CTAC and CTAB binary surfactant mixture was taken and overgrowth of NR was performed it led to the formation of irregularly shaped bars with convex surfaces coming into prominence as the amount of seed was decreased (SI Figure S6). The formation of convex surfaces in the presence of Br − -containing surfactant has been observed earlier, 15,29 and it shows clearly that even in a 1:1 mixture, Br − anions dictates the final morphology, aiding the creation of a convex surface (Figure 4d).…”

“…32 When it comes to mild reducing agent in Au NPs synthesis, AA has been the front runner, however, the narrow pH window of its operation is becoming a detrimental factor. 33 In our earlier work, 29 we have successfully implemented TA for the synthesis of convex Au NCs with HIF (elongated tetrahexahedra, ETHH), and in this work, we have duly used TA for the dimension controlled synthesis of CCB Au NCs. As a matter of fact, synthesis carried out in the presence of AA resulted in CCB Au NCs with poor morphological yield (SI Figure S10).…”

“…In the first step we synthesized Au NRs according to our previous report where tannic acid was used for the first time as a mild reducing agent in seed-mediated growth technique. 29 In the second step, Au NRs were used as seed for the growth of CCB Au NCs in the presence of CTAC surfactant. We could successfully tune the dimensions (∼80 to ∼200 nm) and degree of concavity by varying the amount of seed from 200 to 2.5 μL (Au NRs) and AgNO 3 in the growth solution, respectively.…”

Vibrations of single-crystal gold nanorods and nanowires

“…Their surface is delimited by {7 3 0} planes as observed in elongated tetrahexahedral gold nanocrystals. 19 The half-lengths along the 1 0 0 and 1 1 0 directions (d 100 /2 = 5.296 nm and d 110 /2 = 5.243 nm) were chosen so that the surface area of the cross-section of all the NWs is the same. The results obtained for the dimensions given above can be used to determine the frequencies for different dimensions.…”

Size-tunable uniform gold octahedra: fast synthesis, characterization, and plasmonic properties

“…6,7 The development of selectively synthetic strategy for metal NCs with tailored shapes and sizes has received considerable attention in recent years due to providing an effective approach for precisely tuning the electronic, magnetic, optoelectronic, optical, and catalytic properties of the metal NCs. [8][9][10][11][12][13][14][15] Au NCs, one of the most important noble metal NCs, have been widely researched owing to their high chemical stability and intensive SPR properties. 7,16 To date, a number of synthetic approaches have been developed to afford anisotropic Au NCs in the shapes of cubes, 17 prisms, 18 plates, 19 decahedra, 20 trisoctahedra, 21 rods, 22,23 wires, 24 dendrites, 25 etc.…”