Although gold is the subject of one of the most ancient themes of investigation in science, its renaissance now leads to an exponentially increasing number of publications, especially in the context of emerging nanoscience and nanotechnology with nanoparticles and self-assembled monolayers (SAMs). We will limit the present review to gold nanoparticles (AuNPs), also called gold colloids. AuNPs are the most stable metal nanoparticles, and they present fascinating aspects such as their assembly of multiple types involving materials science, the behavior of the individual particles, size-related electronic, magnetic and optical properties (quantum size effect), and their applications to catalysis and biology. Their promises are in these fields as well as in the bottom-up approach of nanotechnology, and they will be key materials and building block in the 21st century. Whereas the extraction of gold started in the 5th millennium B.C. near Varna (Bulgaria) and reached 10 tons per year in Egypt around 1200-1300 B.C. when the marvelous statue of Touthankamon was constructed, it is probable that “soluble” gold appeared around the 5th or 4th century B.C. in Egypt and China. In antiquity, materials were used in an ecological sense for both aesthetic and curative purposes. Colloidal gold was used to make ruby glass 293 Chem. Rev. 2004, 104, 293−346

Gold nanoparticles: assembly, supramolecular chemistry, quantum-size-related properties, and applications toward biology, catalysis, and nanotechnology.

As a fascinating conjugated polymer, graphitic carbon nitride (g-C3N4) has become a new research hotspot and drawn broad interdisciplinary attention as a metal-free and visible-light-responsive photocatalyst in the arena of solar energy conversion and environmental remediation. This is due to its appealing electronic band structure, high physicochemical stability, and “earth-abundant” nature. This critical review summarizes a panorama of the latest progress related to the design and construction of pristine g-C3N4 and g-C3N4-based nanocomposites, including (1) nanoarchitecture design of bare g-C3N4, such as hard and soft templating approaches, supramolecular preorganization assembly, exfoliation, and template-free synthesis routes, (2) functionalization of g-C3N4 at an atomic level (elemental doping) and molecular level (copolymerization), and (3) modification of g-C3N4 with well-matched energy levels of another semiconductor or a metal as a cocatalyst to form heterojunction nanostructures. The constructi...

Graphitic Carbon Nitride (g-C3N4)-Based Photocatalysts for Artificial Photosynthesis and Environmental Remediation: Are We a Step Closer To Achieving Sustainability?

A fundamental change has been achieved in understanding surface electrochemistry due to the profound knowledge of the nature of electrocatalytic processes accumulated over the past several decades and to the recent technological advances in spectroscopy and high resolution imaging. Nowadays one can preferably design electrocatalysts based on the deep theoretical knowledge of electronic structures, via computer-guided engineering of the surface and (electro)chemical properties of materials, followed by the synthesis of practical materials with high performance for specific reactions. This review provides insights into both theoretical and experimental electrochemistry toward a better understanding of a series of key clean energy conversion reactions including oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER). The emphasis of this review is on the origin of the electrocatalytic activity of nanostructured catalysts toward the aforementioned reactions by correlating the apparent electrode performance with their intrinsic electrochemical properties. Also, a rational design of electrocatalysts is proposed starting from the most fundamental aspects of the electronic structure engineering to a more practical level of nanotechnological fabrication.

Design of electrocatalysts for oxygen- and hydrogen-involving energy conversion reactions

Since the discovery of mechanically exfoliated graphene in 2004, research on ultrathin two-dimensional (2D) nanomaterials has grown exponentially in the fields of condensed matter physics, material science, chemistry, and nanotechnology. Highlighting their compelling physical, chemical, electronic, and optical properties, as well as their various potential applications, in this Review, we summarize the state-of-art progress on the ultrathin 2D nanomaterials with a particular emphasis on their recent advances. First, we introduce the unique advances on ultrathin 2D nanomaterials, followed by the description of their composition and crystal structures. The assortments of their synthetic methods are then summarized, including insights on their advantages and limitations, alongside some recommendations on suitable characterization techniques. We also discuss in detail the utilization of these ultrathin 2D nanomaterials for wide ranges of potential applications among the electronics/optoelectronics, electrocat...

Recent Advances in Ultrathin Two-Dimensional Nanomaterials

Polydopamine and Its Derivative Materials: Synthesis and Promising Applications in Energy, Environmental, and Biomedical Fields

Maintaining nutrient supply, including phosphorus (P), is critical to ensure the adaptation of cropping systems to future elevated CO2 (eCO2) environments. There is much speculation about the role of sparingly soluble sources to supply plants with P so we tested the hypothesis that eCO2 increases plant’s ability to utilise P from sparingly soluble sources via affecting rhizosphere properties. Chickpea and wheat were grown for 6 weeks in washed sand supplied with 40 mg P kg−1 as either readily soluble Ca(H2PO4)2 or sparingly soluble AlPO4 (Al-P), FePO4 or hydroxyapatite (HAP). Half plants were exposed to eCO2 (700 ppm) while the others to ambient CO2 (380 ppm). Elevated CO2 increased biomass production of both species but did not influence P concentration in plants, rhizosphere pH or Olsen P. Among the sparingly soluble P sources, HAP resulted in the maximum biomass and total P uptake in wheat and chickpea with wheat acquiring more P. Supply of nitrate, as compared to urea, to wheat decreased the uptake of P from HAP but increased it from Al-P. Elevated CO2 does not specifically affect plant access to P from sparingly soluble P sources. Urea facilitates P acquisition from HAP whereas nitrate facilitates it from Al-P.

Nitrogen form but not elevated CO2 alters plant phosphorus acquisition from sparingly soluble phosphorus sources

Organic amendments are an option in enhancing soil biological productivity. Limited research exists on the effects of long-term cattle manure addition on low-molecular-weight organic acids (LMWOAs) concentrations in corn (Zea mays L) and soybean (Glycine max L.) fields in the region of soil erosion. The purpose of this study was to investigate the potential influence of cattle manure on the LMWOAs concentration in erosion soil. A field experiment was established in Hailun city, Northeast China to determine the impact of long-term cattle manure addition on the total amounts of main LMWOAs in eroded Mollisol fields. There were three levels of simulated-erosion, which removed 0, 10 and 30 cm of topsoil. Two soil amendments were: (1) chemical fertilizer at the rate normally used by farmers in the region and (2) chemical fertilizer plus 15,000 kg ha−1 (dry weight basis) of cattle manure. Main LMWOAs in soil were assessed at the flowering stage of soybean and the jointing stage of corn. Compared to chemical fertilizer alone, 7-years of repeated cattle manure addition significantly increased total amounts of main LMWOAs in rhizosphere about 9–70 times and bulk soil about 6–62 times. The magnitude of increase by cattle manure was in the order of oxalate>malate>malonate>lactate>maleate in corn plots, and oxalate>malate>malonate>lactate in soybean plots. In comparison, cattle manure and topsoil removal had larger effect on LMWOAs concentrations in corn plot than soybean plot. The addition of cattle manure application and top soil removal had significant independent influence on main LMWOAs concentration in soil solution. This study suggested that addition of cattle manure would be an effective approach in modifying soil biological properties through the increases in low-molecular-weight organic acids to eroded Chinese Mollisols.

Seven years of repeated cattle manure addition to eroded Chinese Mollisols increase low-molecular-weight organic acids in soil solution

Impact of elevated CO2 on C:N:P ratio among soybean cultivars.

Uniform hollow spherical assemblies of ZnSe nanoparticles have been synthesized through a template-free hydrothermal route at low temperature. The product was characterized by means of X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and the Raman spectrum. The two strong Raman vibrational peaks of the ZnSe hollow microspheres indicate a clear shift towards lower frequency, which may be associated with the small size and large surface effects. Also, the ZnSe hollow microspheres show a strong luminescence at about 652 nm.

Template-free solution approach to synthesize ZnSe hollow microspheres

In this work, we described a facile route for the fabrication of free-standing single-walled carbon nanotubes (SWCNT)–CdSe quantum dots (QDs) hybrid ultrathin films and investigated their optoelectronic conversion properties. A free-standing SWCNT film with thickness of ∼36 nm was firstly prepared via vacuum filtration. The film was then immersed into the pre-synthesized oleic acid-capped CdSe QDs (average diameter of 3.5 nm) solution, where CdSe QDs anchored spontaneously onto the surface of SWCNT film to produce SWCNT–CdSe QDs hybrid film. By using pure SWCNT films in different thicknesses as bottom and top electrodes, a flexible all-carbon electrode optoelectronic conversion device with sandwich structure of SWCNT film (thickness of ∼200 nm)/SWCNT–CdSe QDs hybrid film (thickness of ∼36 nm)/SWCNT film (thickness of ∼36 nm) was constructed to generate optoelectronic conversion under illumination of solar-simulated light. Our results demonstrated that the all-carbon electrode structure was effective for charge separation and a sensitive and stable photocurrent signal could be produced in such a device. In addition, our SWCNT–CdSe QDs hybrid film exhibited high flexibility and durability. No clear change in the resistance of the film was detected under bending in various bending angles.

Jian Jin

Papers

Nitrogen form but not elevated CO2 alters plant phosphorus acquisition from sparingly soluble phosphorus sources

Seven years of repeated cattle manure addition to eroded Chinese Mollisols increase low-molecular-weight organic acids in soil solution

Impact of elevated CO2 on C:N:P ratio among soybean cultivars.

Template-free solution approach to synthesize ZnSe hollow microspheres

Free-standing single-walled carbon nanotube–CdSe quantum dots hybrid ultrathin films for flexible optoelectronic conversion devices