Synthesis and Characterization of a Luminol Based Chemiluminescent Trimeric System.

A luminol based chemiluminescent trimeric system, namely 2,3-dihydro-5,8-di(thiophen-2-yl)phthalazine-1,4-dione (T2B-Lum), bearing thiophene rings as donor units and 2,3-dihydrophthalazine-1,4-dione as an acceptor unit was synthesized in two steps via donor-acceptor-donor approach using two different methods. It was found that T2B-Lum emits chemiluminescent light when exposed to H2O2 in a basic medium, and the presence of substituents and the type of aromatic ring bearing chemiluminescent active group have a direct effect on the compound's sensitivity. Among the members of a large family of metal ions, fluorescent and chemiluminescent T2B-Lum exhibited high sensitivity to Cu2+ and Fe3+ ions. Except for other metal cations (silver(I), cadmium(II), cobalt(II), iron(III), lithium(I), magnesium(II), manganese(II), nickel(II), zinc(II)), it has been observed that T2B-Lum is mostly sensitive to copper(II) ions with a detection limit value of 2.2 × 10- 3 M. On the other hand, T2B-Lum was also found to exhibit a high sensitivity to extremely dilute aqueous solutions (e.g., 1:50.000 dilution) of blood samples, making it a promising candidate for use in forensic applications.

Binder- free iridium based electrocatalysts: Facile preparation, high activity and outstanding stability for hydrogen evolution reaction in acidic medium.

Herein, we develop various iridium based catalysts using titania, zirconia and ceria as a supporting material (Ir/MO2; M = Ce, Ti, Zr) for hydrogen evolution reaction (HER). To investigate their electrocatalytic activities, glassy carbon electrodes (GCE) were modified by drop casting the catalyst ink without using any binder. Linear sweep voltammetry (LSV) was used to test their electrocatalytic activities in 0.5 M H2SO4 solution. Among these catalysts, Ir/CeO2 was found to exhibit excellent activity and superior stability. According to the polarization curves, onset potential (η0) and overpotential (η@10 mA.cm-2) of Ir/CeO2 were found as -13 and -23 mV, respectively, which are lower than the values obtained for commercial 10% Pt/C catalyst. Moreover, Ir/CeO2 provides low Tafel slope (38.7 mV.dec-1), high turnover frequency (1.95 @100 mV) and high exchange current density (2.69 mA.cm-2) values. In addition, Ir/CeO2 shows superior stability even after 20 000 cycle in acidic environment (pH = 0.3) which makes Ir/CeO2 (2.44 wt% Ir) as a promising alternative electrocatalyst for HER.

Ceria supported ruthenium(0) nanoparticles: Highly efficient catalysts in oxygen evolution reaction.

Ruthenium(0) nanoparticles were successfully prepared on the surface of ceria (Ru0/CeO2) and used as catalysts on glassy carbon electrode (GCE) in oxygen evolution reaction (OER) from water electrolysis at room temperature. Ru0/CeO2 on GCE exhibits high catalytic activity for OER in alkaline solution. It provides a low onset potential of 1.57 V vs. RHE and low overpotential of 420 mV vs. RHE to reach a current density of 10 mA cm-2. Ru0/CeO2 on GCE shows no change in the onset potential value even after 6.1 h electrochemical measurement in OER.

Titania, zirconia and hafnia supported ruthenium(0) nanoparticles: Highly active hydrogen evolution catalysts.

Designing a cost-effective catalyst with high activity and stability for hydrogen evolution reaction (2H+ + 2e- → H2) is a big challenge due to increasing demand for energy. Herein, we report the electrocatalytic activity of glassy carbon electrodes with group 4 metal oxides (TiO2, ZrO2, HfO2) supported ruthenium(0) nanoparticles in hydrogen evolution reaction. Electrochemical activity of modified electrodes is investigated by recording linear sweep voltammograms in 0.5 M H2SO4 solution. The results of electrochemical measurements reveal that among the three electrodes the glassy carbon electrode with Ru0/TiO2 (1.20% wt. Ru) exhibits the highest activity with a relatively small Tafel slope of 52 mV dec-1, the highest exchange current density of 0.728 mA cm-2, and the smallest overpotential of 41 mV at j = 10 mA cm-2. Furthermore, it demonstrates superior stability in acidic solution with an unaltered onset potential for long term electrochemical measurement.

Nanoceria-Supported Ruthenium(0) Nanoparticles: Highly Active and Stable Catalysts for Hydrogen Evolution from Water.

Ruthenium(0) nanoparticles supported on nanoceria (Ru0/CeO2) were prepared by reduction of Ru3+ ions on the surface of ceria using aqueous solution of NaBH4. The Ru0/CeO2 samples were characterized by advanced analytical tools and employed as electrocatalysts on the glassy carbon electrode (GCE) in hydrogen evolution from water. The GCE, modified by Ru0/CeO2 (1.86 wt % Ru), provides an incredible electrocatalytic activity with a high exchange current density of 0.67 mA·cm-2, low overpotential of 47 mV at j = 10 mA·cm-2, and small Tafel slope of 41 mV·dec-1. Moreover, this modified GCE provides an unprecedented long-term stability without changing the onset potential (33 mV) even after 10 000 scans in acidic water splitting at room temperature. The hydrogen gas, evolved during the water splitting using the Ru0/CeO2 (1.86 wt % Ru) electrocatalyst, was also collected. The amount of the evolved H2 gas matches well with the calculated value, which indicates the achievement of nearly 100% Faradaic efficiency.

A glow in the dark: synthesis and electropolymerization of a novel chemiluminescent terthienyl system.

The synthesis and characterization of a unique (electro)chemiluminescent monomer based on a terthienyl system, and its corresponding polymer which is the first example of an electro-active chemiluminescent polymer bearing a pyridazine appendage, are described.