Investigation and mitigation of reagent ageing during the continuous flow synthesis of patchy particles

Völkl, Andreas; Taylor, Robin N. Klupp

doi:10.1016/j.cherd.2022.03.016

Cited by 4 publications

(8 citation statements)

References 44 publications

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“…In the subsequent patch growth process, which was carried out with reagent concentrations corresponding to n* = 0.996 × 10 6 , a total volume of 8.5 L was produced in approximately 70 min. In earlier work employing non-seeded continuous flow synthesis, we noticed that over such durations, the dilute ammonia solution used can absorb carbon dioxide, leading to a pronounced change in the patch morphology . Moreover, we found that intentionally lowering the pH with nitric acid can, to some extent, mitigate this effect.…”

Section: Resultsmentioning

confidence: 55%

“…Production yields of several grams with such a setup can, in principle, be achieved in a straightforward manner by running the process for a sufficiently long time. Recently, we could show how a possible problem with this, namely, aging of the reagent reservoirs over long periods, could be mitigated …”

Section: Introductionmentioning

confidence: 99%

“…Thus, attempts to control the amount of growth in order to obtain silver patches with targeted size invariably lead to an unwanted influence on the nucleation conditions, resulting in undesirable numbers and sizes of patches on the silica cores, or even a large fraction of bare cores . Through the use of a cascaded two-T mixer process and making use of the kinetic control afforded to the reaction by the ammonia concentration, we were able to partially separate nucleation from growth, but not sufficiently for control of patch size . Such control, however, is essential in order to design arbitrary patchy particle morphologies for application as anisotropic building blocks, or, as already noted above, to achieve a wide tunability of the LSPR.…”

Section: Introductionmentioning

confidence: 99%

“…Recently, we could show how a possible problem with this, namely, aging of the reagent reservoirs over long periods, could be mitigated. 46 One very significant limitation of our approach results from its extreme simplicity. Performed as a single step, the electroless deposition conditions, which result from the initial reagent concentrations, define both the nucleation and growth rate.…”

Section: ■ Introductionmentioning

confidence: 99%

“…47 Through the use of a cascaded two-T mixer process and making use of the kinetic control afforded to the reaction by the ammonia concentration, we were able to partially separate nucleation from growth, but not sufficiently for control of patch size. 46 Such control, however, is essential in order to design arbitrary patchy particle morphologies for application as anisotropic building blocks, 48 or, as already noted above, to achieve a wide tunability of the LSPR.…”

Section: ■ Introductionmentioning

confidence: 99%

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Gram-Scale Continuous Flow Synthesis of Silver-on-Silica Patchy Nanoparticles with Widely Tunable Resonances for Plasmonics Applications

Völkl

Jannick

Drobek

et al. 2023

ACS Appl. Nano Mater.

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Extensive research has been conducted on colloids that incorporate nanostructured noble metals, motivated in particular by their highly tunable optical properties. However, the lack of approaches that offer reproducibility, tunability, and scalable production is limiting their exploitation in many application areas. Here, we present an innovative process for the controlled formation of silver patches on silica nanospheres using gold nanocrystal seeds. The synthesis of the seeds and their attachment in very small numbers to the silica spheres is achieved without employing any surfactants, stabilizers, or linker molecules. Using advanced transmission electron microscopy techniques, we show that electroless deposition of nanostructured silver occurs at the introduced seeds and leads to a central protrusion from the metal patches not observed in earlier, seed-free work. We demonstrate that both seeding and growth processes can be achieved in millimixer flow reactors. With this simple and scalable approach, we provide compelling evidence for the use of seeds in producing targeted morphology and function. Specifically, patch size and optical properties can be tailored in a predictive manner by adjusting the density of seeds on the silica nanospheres as well as reagent concentrations during growth. As a result, our process can be used to obtain colloidal dispersions with localized surface plasmon resonance peaks anywhere in the range 400 to nearly 1300 nm. We confirm the scalability of our method by operating the growth process for around 70 min. Apart from changes in the first few minutes, the product properties remained rather stable and over a gram of high quality silver patch-coated silica could be recovered. Our approach opens up exciting new avenues for plasmonics applications, which typically require large amounts of nanoparticles with specifically designed optical properties. These include color and IR pigments, photocatalysts, and as light management components in optoelectronic devices like photovoltaic cells.

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Section: Resultsmentioning

confidence: 55%

Section: Introductionmentioning

confidence: 99%