Electrochemiluminescence (ECL) is chemiluminescence triggered by electrochemical techniques. More than 150 ECL assays with remarkably high sensitivity and extremely wide dynamic range are currently available, and accounts for hundreds of millions of dollars in sales per year. The recent development of ECL is particularly rapid. After a brief introduction to ECL, this critical review presents the active and/or emerging areas of ECL research as well as new applications and phenomena of ECL, such as light-emitting electrochemical cell, wireless electrochemical microarray using ECL as photonic reporter, high throughput analysis, aptasensors, immunoassays and DNA analysis, ECL of nanoclusters and carbon nanomaterials, ECL imaging techniques, scanning ECL microscopy, colorimetric ECL sensor, surface plasmon-coupled ECL, electrostatic chemiluminescence, soliton-like ECL waves, ECL investigation of molecular interaction, and single molecule detection. Finally, some perspectives on this rapidly developing field are discussed (322 references).

The great success of electrochemiluminescence (ECL) for in vitro diagnosis (IVD) and its promising potential in light-emitting devices greatly promote recent ECL studies. More than 45% of ECL articles were published after 2010, and the first international meeting on ECL was held in Italy in 2014. This critical review discusses recent vibrant developments in ECL, and highlights novel ECL phenomena, such as wireless ECL devices, bipolar electrode-based ECL, light-emitting electrochemical swimmers, upconversion ECL, ECL resonance energy transfer, thermoresponsive ECL, ECL using shape-controlled nanocrystals, and ECL as an ion-selective electrode photonic reporter, a paper-based microchip, and a self-powered microfluidic ECL platform. We also comment on the latest progress in bioassays, light-emitting devices and, the computational approach for the ECL mechanism study. Finally, perspectives and key challenges in the near future are addressed (198 references).

A versatile method for selectively synthesizing single-crystalline rhombic dodecahedral, cubic, and octahedral palladium nanocrystals, as well as their derivatives with varying degrees of edge- and corner-truncation, was reported for the first time. This is also the first report regarding the synthesis of rhombic dodecahedral palladium nanocrystals. All the nanocrystals were readily synthesized by a seed-mediated method with cetyltrimethylammonium bromide as surfactant, KI as additive, and ascorbic acid as reductant. At the same ascorbic acid concentration, a series of palladium nanocrystals with varying shapes were obtained through manipulation of the concentration of KI and the reaction temperature. The formation of different palladium facets were correlated with their growth conditions. In the absence of KI, the 100 palladium facets are favored. In the presence of KI, the concentration of KI and the reaction temperature play an important role on the formation of different palladium facets. The 110 palladium facets are favored at relatively high temperatures and medium KI concentrations. The 111 palladium facets are favored at relatively low temperatures and medium KI concentrations. The 100 palladium facets are favored at either very low or relatively high KI concentrations. These correlations were explained in terms of surface-energy and growth kinetics. These results provide a basis for gaining mechanistic insights into the growth of well-faceted metal nanostructures.

This paper reports a versatile seed-mediated growth method for selectively synthesizing single-crystalline rhombic dodecahedral, octahedral, and cubic gold nanocrystals. In the seed-mediated growth method, cetylpyridinium chloride (CPC) and CPC-capped single-crystalline gold nanocrystals 41.3 nm in size are used as the surfactant and seeds, respectively. The CPC-capped gold seeds can avoid twinning during the growth process, which enables us to study the correlations between the growth conditions and the shapes of the gold nanocrystals. Surface-energy and kinetic considerations are taken into account to understand the formation mechanisms of the single-crystalline gold nanocrystals with varying shapes. CPC surfactants are found to alter the surface energies of gold facets in the order {100} > {110} > {111} under the growth conditions in this study, whereas the growth kinetics leads to the formation of thermodynamically less favored shapes that are not bounded by the most stable facets. The competition between AuCl(4)(-) reduction and the CPC capping process on the {111} and {110} facets of gold nanocrystals plays an important role in the formation of the rhombic dodecahedral (RD) and octahedral gold nanocrystals. Octahedral nanocrystals are formed when the capping of CPC on {111} facets dominates, while RD nanocrystals are formed when the reduction of AuCl(4)(-) on {111} facets dominates. Cubic gold nanocrystals are formed by the introduction of bromide ions in the presence of CPC. The cooperative work of cetylpyridinium and bromide ions can stabilize the gold {100} facet under the growth condition in this study, thereby leading to the formation of cubic gold nanocrystals.

Ruthenium(II) tris(2,2'-bipyridyl) ([Ru(bpy) 3 ] 2+ ) has received increasing attention in clinical diagnosis and scientific research because of its high sensitivity, wide dynamic range, stability, simplicity, and versatility as an electrochemiluminescent probe. [1] As the electrochemiluminescence (ECL) results from electrochemical reactions between [Ru(bpy) 3 ] 2+ and co-reactants, extensive research has been focused on exploring effective co-reactants for the sensitive determination of [Ru(bpy) 3 ] 2+ , which has important bioanalytical applications. [2] In 1984, Bard and co-workers first reported the determination of [Ru(bpy) 3 ] 2+ ECL using either oxalate or peroxydisulfate as co-reactants. [3] Later, Leland and Powell suggested tripropylamine (TPA) as a co-reactant, [4] and Blackburn et al. soon developed [Ru(bpy) 3 ] 2+ ECL immunoassays and DNA probe assays using TPA as co-reactant and [Ru(bpy) 3 ] 2+ as the label. [5] [Ru(bpy) 3 ] 2+ /TPA ECL assays have been widely used for over fifteen years now. [2,6] Despite its exclusive popularity, TPA has several important disadvantages. [2] First, TPA is toxic and volatile, but it is used in high concentrations (usually up to 100 mm) to attain good sensitivity. Second, its slow electrochemical oxidation rate limits ECL efficiency. Third, high concentrations of acidic phosphate solutions are needed to prepare concentrated neutral solutions of TPA because TPA is basic. Finally, the ECL intensity of the [Ru(bpy) 3 ] 2+ /TPA system depends strongly on electrode materials. For example, the ECL intensity at Pt electrodes is only about 10 % of that at Au electrodes. Thus, it is desirable to find alternatives to TPA.Several groups have studied the ECL from [Ru(bpy) 3 ] 2+ / amine systems under the condition that the concentrations of [Ru(bpy) 3 ] 2+ are higher than that of amines. [2,7] Generally; tertiary amines are more effective than secondary amines, primary amines, and other kinds of co-reactants. Also, electron-donating groups tend to increase ECL. It seemed impossible to find better co-reactants. Recent studies showed that ECL efficiencies can be improved through increasing the electrochemical oxidation rate of amines when the concentration of [Ru(bpy) 3 ] 2+ is much lower than that of the amines, as in the cases of ECL immunoassays and DNA probe assays. To our knowledge, all methods reported to date use additives to increase the oxidation rate of amines and, thus, ECL efficiencies. [8] Also, there have been only a few reports that attempt to find better co-reactants from easily oxidizable tertiary amines.Herein, we report an investigation of the ECL of a series of tertiary amines with various substituents whilst keeping the concentration of [Ru(bpy) 3 ] 2+ lower than that of the amine. The purpose of the present study is to provide a new way to enhance ECL efficiencies by using easily oxidizable tertiary amines, and develop more efficient and environmentally friendly co-reactants for ECL immunoassays and DNA probe assays. Figure 1 shows the dependence of ECL...

Nearly monodisperse Pd nanocubes with controllable sizes were synthesized through a seed-mediated growth approach. By using Pd nanocubes of 22 nm in size as seeds, the morphology of the as-grown nanostructures was fixed as single-crystalline, which enabled us to rationally tune the size of Pd nanocubes. The formation mechanism of initial 22 nm nanocubes was also discussed. The size-dependent surface plasmon resonance properties of the as-synthesized Pd nanocubes were investigated. Compared with previous methods, the yield, monodispersity, perfection of the shape formation, and the range of size control of these nanocubes are all improved. These Pd nanocubes may have potential interests in surface-enhanced Raman scattering, sensors, catalysis, study of size-dependent properties, and fabrication of high-order structures.

Single-walled carbon nanohorns (SWCNHs) are horn-shaped single-walled tubules with a conical tip. They are generally synthesized by laser ablation of pure graphite without using metal catalyst with high production rate and high yield, and typically form radial aggregates. SWCNHs are essentially metal-free and very pure, which avoids cumbersome purification and makes them user-friendly and environmentally benign. Currently, SWCNHs have been widely studied for various applications, such as gas storage, adsorption, catalyst support, drug delivery system, magnetic resonance analysis, electrochemistry, biosensing application, photovoltaics and photoelectrochemical cells, photodynamic therapy, fuel cells, and so on. This review outlines the research progress on SWCNHs, including their properties, functionalization, applications, and outlook.

Nitrogen, phosphorus and oxygen tri-doped porous graphite carbon@oxidized carbon cloth electrodes exhibit excellent activity and durability for full water splitting at all pH values.