Nanocrystals are fundamental to modern science and technology. Mastery over the shape of a nanocrystal enables control of its properties and enhancement of its usefulness for a given application. Our aim is to present a comprehensive review of current research activities that center on the shape-controlled synthesis of metal nanocrystals. We begin with a brief introduction to nucleation and growth within the context of metal nanocrystal synthesis, followed by a discussion of the possible shapes that a metal nanocrystal might take under different conditions. We then focus on a variety of experimental parameters that have been explored to manipulate the nucleation and growth of metal nanocrystals in solution-phase syntheses in an effort to generate specific shapes. We then elaborate on these approaches by selecting examples in which there is already reasonable understanding for the observed shape control or at least the protocols have proven to be reproducible and controllable. Finally, we highlight a number of applications that have been enabled and/or enhanced by the shape-controlled synthesis of metal nanocrystals. We conclude this article with personal perspectives on the directions toward which future research in this field might take.

Shape‐Controlled Synthesis of Metal Nanocrystals: Simple Chemistry Meets Complex Physics?

2.2. Fenton’s Chemistry 6575 2.2.1. Origins 6575 2.2.2. Fenton Process 6575 2.3. Photo-Fenton Process 6577 3. H2O2 Electrogeneration for Water Treatment 6577 3.1. Fundamentals 6578 3.2. Cathode Materials 6579 3.3. Divided Cells 6580 3.4. Undivided Cells 6583 4. Electro-Fenton (EF) Process 6585 4.1. Origins 6585 4.2. Fundamentals of EF for Water Remediation 6586 4.2.1. Cell Configuration 6586 4.2.2. Cathodic Fe2+ Regeneration 6586 4.2.3. Anodic Generation of Heterogeneous Hydroxyl Radical 6587

Electro-Fenton process and related electrochemical technologies based on Fenton's reaction chemistry

基礎講座 電気泳動(Electrophoresis)

Biosorbents for heavy metals removal and their future

The major strategies for designing surfaces that prevent fouling due to proteins, bacteria, and marine organisms are reviewed. Biofouling is of great concern in numerous applications ranging from biosensors to biomedical implants and devices, and from food packaging to industrial and marine equipment. The two major approaches to combat surface fouling are based on either preventing biofoulants from attaching or degrading them. One of the key strategies for imparting adhesion resistance involves the functionalization of surfaces with poly(ethylene glycol) (PEG) or oligo(ethylene glycol). Several alternatives to PEG-based coatings have also been designed over the past decade. While protein-resistant coatings may also resist bacterial attachment and subsequent biofilm formation, in order to overcome the fouling-mediated risk of bacterial infection it is highly desirable to design coatings that are bactericidal. Traditional techniques involve the design of coatings that release biocidal agents, including antibiotics, quaternary ammonium salts (QAS), and silver, into the surrounding aqueous environment. However, the emergence of antibiotic- and silver-resistant pathogenic strains has necessitated the development of alternative strategies. Therefore, other techniques based on the use of polycations, enzymes, nanomaterials, and photoactive agents are being investigated. With regard to marine antifouling coatings, restrictions on the use of biocide-releasing coatings have made the generation of nontoxic antifouling surfaces more important. While considerable progress has been made in the design of antifouling coatings, ongoing research in this area should result in the development of even better antifouling materials in the future.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/adma.201001215

Antifouling coatings: recent developments in the design of surfaces that prevent fouling by proteins, bacteria, and marine organisms.

The marine algae Sargassum sp, Padina sp, Ulva sp, and Gracillaria sp, harvested locally, were investigated for their biosorption performance in the removal of lead, copper, cadmium, zinc, and nickel from dilute aqueous solutions It was found that the biosorption capacities were significantly affected by solution pH, with higher pH favoring higher metal-ion removal Kinetic and isotherm experiments were carried out at the optimal pH: at pH 50 for lead and copper, and at pH 55 for cadmium, zinc, and nickel The metal removal rates were rapid, with 90% of the total adsorption taking place within 60 min Sargassum sp and Padina sp showed the highest potential for the sorption of the metal ions, with the maximum uptake capacities ranging from 061 to 116 mmol/g for Sargassum sp and 063 to 125 mmol/g for Padina sp The general affinity sequence for Padina sp was Pb>Cu>Cd>Zn>Ni, while that for Sargassum sp was Pb>Zn>Cd>Cu>Ni XPS and FTIR analysis of Sargassum sp and Padina sp revealed the chelating character of the ion coordination to carboxyl groups It was confirmed that carboxyl, ether, alcoholic, and amino groups are responsible for the binding of the metal ions

Sorption of lead, copper, cadmium, zinc, and nickel by marine algal biomass: characterization of biosorptive capacity and investigation of mechanisms

This paper describes the synthesis of single-crystalline Ag nanoplates using the extract of unicellular green alga Chlorella vulgaris at room temperature. Proteins in the extract were involved in the biological synthesis, providing the dual function of Ag ion reduction and shape-controlled synthesis of nanosilver. Hydroxyl groups in Tyr residues and carboxyl groups in Asp and/or Glu residues were further identified as the most active functional groups for Ag ion reduction and for directing the anisotropic growth of Ag nanoplates, respectively. The kinetics of Ag ion reduction in biological systems was discussed and probed by using custom-designed peptides. The results showed the Tyr content (the reduction source) and the content of Ag complexers (the reaction inhibitors, e.g., His and Cys) in the protein molecules as important factors affecting the reduction kinetics. The comprehensive system identification effort has led to the design of a simple bifunctional tripeptide (DDY-OMe) with one Tyr residue as ...

Silver nanoplates: from biological to biomimetic synthesis.

Characterization of PEI-modified biomass and biosorption of Cu(II), Pb(II) and Ni(II).

Heavy metal pollution in the aqueous environment is a problem of global concern. Biosorption has been considered as a promising technology for the removal of low levels of toxic metals from industrial effluents and natural waters. A modified fungal biomass of Penicillium chrysogenum with positive surface charges was prepared by grafting polyethylenimine (PEI) onto the biomass surface in a two-step reaction. The presence of PEI on the biomass surface was verified by FTIR and X-ray photoelectron spectroscopy (XPS) analyses. Due to the high density of amine groups in the long chains of PEI molecules on the surface, the modified biomass was found to possess positive zeta potential at pH below 10.4 as well as high sorption capacity for anionic Cr(VI). Using the Langmuir adsorption isotherm, the maximum sorption capacity for Cr(VI) at a pH range of 4.3−5.5 was 5.37 mmol/g of biomass dry weight, the highest sorption capacity for Cr(VI) compared to other sorbents reported in the literature. Scanning electronic mi...

Polyethylenimine-modified fungal biomass as a high-capacity biosorbent for Cr(VI) anions: sorption capacity and uptake mechanisms.

In this work, single-crystalline gold nanoplates were produced by treating an aqueous solution of chloroauric acid with the extract of the unicellular green alga Chlorella vulgaris at room temperature. The results suggest proteins as the primary biomolecules involved in providing the dual function of Au(III) reduction and the size- and shape-controlled synthesis of the nanogold crystals. A protein with a molecular weight of approximately 28 kDa was isolated and purified by reversed-phase HPLC; this protein tested positive for the reduction of chloroauric acid in aqueous solution. The isolated protein (named gold shape-directing protein, or GSP for convenience) was then used to produce gold nanoplates with distinctive triangular and hexagonal shapes in high yields (approximately 90 %). The kinetics of the reduction reaction could be manipulated through changes in the GSP concentration to produce plates with lateral sizes ranging from nanometers to micrometers. The growth of gold nanoplates in the GSP solution with time was monitored by microscopic and spectroscopic techniques, thereby allowing the detection of several key intermediates in the growth process.

Yen-Peng Ting

Papers

Sorption of lead, copper, cadmium, zinc, and nickel by marine algal biomass: characterization of biosorptive capacity and investigation of mechanisms

Silver nanoplates: from biological to biomimetic synthesis.

Characterization of PEI-modified biomass and biosorption of Cu(II), Pb(II) and Ni(II).

Polyethylenimine-modified fungal biomass as a high-capacity biosorbent for Cr(VI) anions: sorption capacity and uptake mechanisms.

Identification of active biomolecules in the high-yield synthesis of single-crystalline gold nanoplates in algal solutions.