Plasmonic Gold Nanoparticles as Designing Caps

Plasmonic nanomaterials have attracted significant interest because of its wide variety of applications such as sensing, energy conversion, photothermal therapy etc. Among the various plasmonic inorganic metals (Ag, Cu, Al, and Au) Au shows the excellent biocompatibility, chemical stability, and rich surface functionality. It can be seen that some new approaches have include the construction of metal shells on dielectric nanoparticles, and the control of island growth on nanoparticles and nanorods over the design of narrow gaps via nanoplates or nanoshells. Also, the conventional modulation of plasmonics via the control of shape, size and the aspect ratio of nanomaterials. The structural control have also arises from the active surface growth. As a result, the dynamic competition between ligand absorption and metal deposition occurs [1].

The properties of plasmonic nanostructures are highly dependent on its surface morphology, however, there are a very few methods for appending the domain as the “functional group” or modifiers. The fundamental control of the domain appending on a seed nanoparticle is via the interfacial energy and the wetting growth mode leads to the conformal coating on the seed. Also, the modulation of plasmonics will essentially control the size of the seed. Here they have studied a systematic analysis on the growth of Au caps over Au seeds via simultaneously for the use of a hydrophobic thiol ligand and surfactant. Moreover, this combination have achieved a powerful control for the active surface which leads to a dynamic modulation of spreading the vertical growth of the Au caps. By modulating the plasmonic properties, this methodology offers a wide variety of caps and modulate Au hats on Au nanoparticles, which includes of helmets, crowns, antler hats, antenna hat, beret hats and mortar boards [1].

Plasmonic modulations need more synthetic handles with a systematic development from the perspectives of synthetic advance is of a critical importance. The main prerequisite for tuning cap morphology is the stable and monodispersed AuNPs. Strong hydrophobic ligand of 4,5-diphenyl-2-imidazolethiol (DPI) was used with the combination of a cationic surfactant myristyl trimethyl ammonium bromide (MTAB). It can be found that a serious aggregation have caused due to the exchange of direct ligand between DPI and citrate. Therefore, at first we need to replace the citrate with MTAB thus, the resulting mixture will be highly stable and are used as the stock solutions for all the synthesis. DPI was further added to functionalize and activate the Au surface [1].

Figure 1. Schematic representation of the synthesis of mortarboard, helmet and beret hat [1].

At each side of Au seed, a domain growth was observed (Figure 1) when the concentration of NaOH is found to be 0.825 mM, 64% of the domains found to be nanoplate, and the remaining are of polyhedrons. 68% of nanoplate were attached tangent to the spherical seeds and placed via its center and it is named as mortar board for the structural similarity. However, when the concentration of NaOH was increased to 3.96 mM, then the initial color change was occurred after 2 minutes. Here, the emerging Au domain will become more thicker with an obvious curvature, appearing as a helmet on the seed nanoparticle, instead of nanostructures with plate shapes.

To explore the intermediate states, a series of reaction is carried out between the mortar board and the helmet which are distinctively different form of the growth modes. On comparison to the helmets, the thickness of the helmets and beret hats are found to be similar, with the only main differences was the coverage of the seed. The growth of island domain on a seed is essentially found to be a solid–solid wetting phenomenon. As per the literature reports, when a metal domain is directly grown on a metal seed, then it is due to the wetting growth mode. On the other hand, if the metal domain is grown on the ligand covered metal surface, then it is due to the non-wetting growth mode. It can be obviously seen that, the formation of the helmet was not instantaneous, however it gradually grows with its size and coverage [2].

The main critical factor is the dynamic competition between ligand inhibition and the Au deposition. The possible outcome with varying the reduction rates will leads to the different morphologies of the new Au domains. Moreover, 20% of the nanoplates were attached to the side of the seeds which may arise from the independently developed new Au domain of random twinning. Also, the twinning is not occur for all the nuclei, with mainly 36% of the Janus nanostructures did not show any plate morphological structures.

Figure 2. Schematic representation of the active surface growth [1].

As it can be seen that, some of the sites (Figure 2) seems to be new and some may be old, the differentiation can be explained by the non-uniform spreading and the formation of petals. For pushing the limit of spreading growth, they tried to increase the amount of Au growth on each seed. The reactants were also kept at the same concentration to maintain the growth mode.

Figure 3. Schematic representation of the growth of crown, antler hats and antennas [1].

When the concentration of NaOH is further increased to 6.6mM, there is no any structural changes. Moreover, to the increase the rate of reduction, they have tried to increase the concentration of the reductant 2,7-dihydroxynaphthalene (DHN). While, the emerging hat is still on the seed, and its shape has evolved to complete with various different forms. Hence, there is sign of vertical active surface growth in addition to the spreading growth [1].

Our SNB team have emphasize this research article to enrich our viewer’s knowledge about the study on a systematic analysis on the growth of gold caps over Au seeds via simultaneously with a hydrophobic thiol ligand and surfactant for designing the caps (helmets, crowns, antler hats, antenna hat, beret hats and mortarboards). The morphological structures and plasmonic property of a nanomaterials are highly attentive in the research work. The dynamic role and competition between the concern growth sites in contrast to the wetting growth was developed via active nature of surface growth. This will give rise to the encapsulation of shells, while the non-wetting growth gives to appending spheres. Hence, they reported that the active surface growth methodology is an fruitful and effective one to enrich a structural modulation for appending the domain of Au seeds.

References

[1] X. Tian, et al., ChemSci., (2021), DOI: 10.1039/d0sc05780k.

[2] J. Huang, et al., Nano Lett., 16, 617 (2016).

--- Dr. Y. Sasikumar

Author Profile

Comments

PROSPECTS ON PHOTOBIOREFINERY

Very recently, Prof. Dr. K. Faungnawakij and his research group have summarized a mini review report on an emerging renewable technique of Photobiorefinery . This is one of the beyond technique of Artificial Photosynthesis (AP) [1] . Despite great promises, AP technologies for solar H2 production and CO2 reduction are far uncompetitive to other promising technologies at the current stage . However, despite an enormous effort, time, and budget paid on AP-related researches throughout several decades, AP technologies have struggled to strive beyond laboratory demonstration except a very few exceptions [2] . This bitter reality makes the translation of this excellent science to practical application questionable [3] . Technoeconomic analysis shows that without achieving the aggressive technology targets, this technology will not be commercially viable. This has directed the research community towards the development of highly efficient yet expensive devices. While tremendous p...

Impact on Climate and Land Use Changes Around Ganga River

In India, Ganga is the largest river and also famous spiritual river, in meantime pollution issue in Ganga river is considered to be one of the most discussed topics on river water quality in the past decades . The river gets s everely polluted with untreated industrial and human wastes, and the river crossed around 11 states in India and provides water for about 40% of India's population, approximately 500 million people, we couldn’t find more than any other river in the world [ 1, 2 ]. Central Pollution Control Board (CPCB) has mentioned that 764 grossly polluting industries were discharging into the Ganga river, 487 industries are from the Kanpur region. Therefore, the Kanpur region was treated as the main polluted spot and immediate action should be taken for further recovery of water quality. The Kanpur region is one of the most important industrialized place in India. It is the most polluted stretch of the Ganga River, because of its excessive pollutant discharge from the i...

Electric Vehicle: Public Health and Climate Benefits

A research team led by Daniel Peters at Northwestern University has investigated that if we introducing electrifying vehicles in the streets of the United States could annually prevent hundreds-to-thousands of premature accidental deaths.This work highlights the potential of a synergistic solution to reduce CO 2 emissions by hundreds to millions of tons annually. The estimate of economic damages induced by introducing electrifying vehicles (EV) adoption is substantial. With current infrastructure, about 25% of electrifying vehicles adoption in the US can save approximately $16.8 billion annually, has been told in the study entitled"Public Health and Climate Benefits and Trade offs of U.S. Vehicle Electrification," in GeoHealth on 13 th August 2020 [1] . Vehicle electrification in the United States could prevent hundreds to thousands of premature deaths annually while reducing carbon emissions by hundreds of millions of tons. This highlights the potential of co-beneficial...

Efficient Bio-Diesel Synthesis: Reusable Magnetic Catalysis

Prof. Anping Wang et al., with his research collaborative team from china ( 1. Guizhou University, China; and 2. Guizhou Normal University, China) and India (National Chemical Laboratory, India) have reviewed the research over views on the preparation methods, physicochemical properties, stabilization/functionalization, and the catalytic applications of magnetic materials, including magnetic acids, bases, enzymes, and acid-base bifunctional materials for the synthesis of bio-diesel. Here, we discuss only the preparation of efficient bio-diesel with merits and applications of magnetic nanocatalyst for the bio-diesel preparation . Bio-diesel products are mainly attain from bio mass feed stocks, which gives more attention in the biorefinery research affairs [1]. A green way of renewable liquid biofuels are emergency required one in present atmosphere. Among the various classes, best one is renewable diesel fuel, the chemical content of long-chain fatty acid methyl ester (FAME) or ethy...

Scientific Research Focus on “To End Hunger”

According to the Food and Agriculture Organization of the United Nations (FAO UN), Hunger Report, Ending hunger is a major objective of the United Nations’ (UN) Sustainable Development Goals (SDG), hunger is the term used to define periods when populations are experiencing severe food insecurity - means that they go for entire days without eating due to lack of money, lack of access to food, or other resources [ 1 ]. Hunger is strongly interconnected with poverty, and it involves interactions among an array of social, political, demographic, and societal factors. An attention is must in the following topics to put an end card for poor hunger: Global Hunger Index (GHI). World Food Program’s 2020. Global Report on Food Crises. Smallholder-farming. Ceres2030. The two main international institutions are the International Institute for Sustainable Development (IISD) and the International Food Policy Research Institute (IFPRI) , joined forces to estimate what it would cost to ...

Threatened Species: An Alert of Red List from IUCN

International Union for Conservation of Nature (IUCN) organization was established in 1964 to safeguard our natural species information details. This organization helps to identify the species when these are diminished due to abnormal issues in environmental forces or evolutionary changes in their population numbers. IUCN was recommended the information on the global risk status of plants, fungus, and animal species [1] . Overall world, the term “Biodiversity” and their conservation progress is an attentive one. As per IUCN, the announced Red List shows a critical condition of the world’s natural biodiversity. The major part of assessments representing on the Red List (in IU CN) are accounted out by following government/non-government members: Species Survival Commission (SSC). Red List Partners . Red List Authorities (RLAs). O ther specialists (who working on assessment projects). It gives information about the probable range, habitat, populat...

RENEWABLE ENERGY'S ROLE IN ENVIRONMENTAL CLEEN-UP PROCESS

Human activity is overloading our atmosphere with carbon dioxide and other global warming emissions. These gases act like a blanket, trapping heat. The result is a web of significant and harmful impacts, from stronger, more frequent storms, to drought, sea level rise, and extinction. Most of global warming emissions come from our electricity sector. Most of those emissions come from fossil fuels like coal and natural gas . Sulfur dioxide (SO2) , which cause acid rain, comes from electricity generation. Nitrogen oxides (NOx) , which react with sunlight to create ground level ozone and smog, come from electricity generation. Ozone (O3) occurs naturally in the upper atmosphere where it is beneficial. Particulate matter is a type of air pollution more commonly referred to as soot. Carbon dioxide (CO 2 ) is a greenhouse gas that contributes to global climate change. Mercury is a highly toxic metal that is released from coal-fired power plants. In contra...

Detection and Diagnosis: Heavy Toxic Metals

Prof. Youzhi Li, from Hunan Agricultural University, Changsha, China and his research team have recently published, “Total concentrations and sources of heavy metal pollution in global river and lake water bodies from 1972 to 2017”. They discussed on heavy metals like lead (Pb) cause a severe threat to living beings because of its toxicity and bioaccumulation. Heavy metals like lead (Pb) cause a severe threat to living beings because of its toxicity and bioaccumulation. Amongst the heavy metals, lead (Pb) is the well-known one for its historical use in paints, petrol, and fuse joints in water pipes. Though the tradition of using Pb has been considerably decreased in recent years, Pb in drinking water still remains to be a problem for many societies around the world [ 1 ]. Hence, it is one of the supreme importance to monitor the levels of Pb in drinking water, so that contamination can be promptly identified and moderated. The World Health Organization (WHO) mentions a guideline l...

Innovations of Integrated Artificial Intelligence

Artificial intelligence (AI) is the study of methods to imitate intelligent human behavior. AI is widely heralded as an ongoing “revolution” transforming science and society altogether [ 1 , 2 ]. While approaches to AI such as machine learning, deep learning and artificial neural networks are reshaping data processing and analysis [ 3 ], healthcare, transportation and the production chain [ 4 ]. Figure 1. Integrated concept of artificial intelligence. AI Ethics Guidelines National and international organizations (European Commission, Organisation for Economic Co-operation and Development (OECD), UK House of Lords, Singapore Commission) have responded to these concerns by developing ad hoc expert committees on AI, often mandated to draft policy documents in various countries. In 2018 alone, companies such as Google and SAP publicly released AI guidelines and principles. The advisory council on the ethical use of AI scientific team have announced that results reveal a global co...

Search This Blog