Fabrication of a Hierarchical TiO2 Microsphere/Carbon Dots Photocatalyst for Oxygen Evolution and Dye Degradation Under Visible Light.

Anatase hierarchical TiO2 microsphere/carbon dots composite (HTM/CDs) was fabricated by a facile method for active visible light photocatalysis. The phase, morphology, microstructure and optical properties were investigated by X-ray diffraction, scanning electronmicroscopy, transmission electron microscopy and UV-VIS diffuse reflectance spectroscopy respectively. Under visible light illumination, the fabricated HTM/CDs composite was exhibited an enhanced photo catalytic activity compared to that of pure hierarchical TiO2 microspheres (HTM). Such an enhancement in photocatalytic activity can be attributed to an increase in the absorption of visible light. The photocatalytic activity was investigated by the degradation of a model dyemalachite green (MG) and oxygen production through water splitting.We believe that this type of hybrid material could be used as a highly active and stable visible light photocatalyst to remove pollutants as well as energy production with high performance.

µ-Pyridine-bridged copper complex with robust proton-reducing ability.

The binuclear copper complex [Cu(DQPD)]2 (where DQPD = deprotonated N2,N6-di(quinolin-8-yl)pyridine-2,6-dicarboxamide (DQPDH2)) was synthesised and characterised by various spectroscopic as well as electrochemical techniques. The binuclear copper complex was converted into a mononuclear one by the addition of 2 equivalents of pTsOH into [Cu(DQPD)]2. The interconversion between the dimer and monomer complex was studied through UV-Vis spectroscopy and cyclic voltammetry. The mononuclear copper complex showed high catalytic activity towards electrochemical proton reduction using acetic acid as the external proton source in 95 : 5 (v/v) DMF/H2O. It showed an ic/ip (where ic is the catalytic current in the presence of acetic acid and ip is the reduction peak current in absence of acid) value of 24 and a turnover rate (TOF) of 111.70 s-1 at a scan rate of 100 mV s-1 at 25 °C. The [Cu(DQPD)]2 complex evolved hydrogen under the irradiation of visible light in the presence of fluorescein (Fl) as a photosensitizer and triethylamine (TEA) as the sacrificial electron donor with an initial TOF of 0.03 s-1 with respect to the catalyst.

Proton reduction by a nickel complex with an internal quinoline moiety for proton relay.

The complex Ni(DQPD) (where DQPD = deprotonated N(2),N(6)-di(quinolin-8-yl)pyridine-2,6-dicarboxamide (DQPDH2)) behaves as a visible light driven active catalyst to reduce protons from water when employed with the photosensitizer fluorescein (Fl) and triethylamine (TEA) as the sacrificial electron donor. The photocatalytic system shows very high activity, attaining 2160 turnovers and an initial turnover rate of 0.032 s(-1) with respect to the catalyst. The proposed electrocatalytic mechanism is of the CECE type (C is a chemical step protonation and E is the electrochemical step reduction), where the Ni(DQPD) catalyst undergoes rapid protonation at the non-coordinating nitrogen atom of the quinoline before undergoing reduction. The location of the pendant base is a key factor such that the N-H resulting from the protonation of the non-coordinating nitrogen atom of the quinoline is properly located to interact with the Ni-H hydride leading to heterocoupling between protons and hydrides. Theoretical calculations for the catalytic system were carried out using the density functional level of theory (DFT) and are consistent with a mechanism for catalysis in a polypyridine nickel system. This is the first report of a polypyridine based nickel catalyst where the pendant base is responsible for the internal proton relay towards the metal center through the heterocoupling between protons and hydrides to generate hydrogen.

[RuV(NCN-Me)(bpy)(=O)]3+ Mediates efficient C­H bond oxidation from NADH analogs in aqueous media rather than water oxidation

[Ru(V)[double bond, length as m-dash]O](3+) and [Ru(VI)[double bond, length as m-dash]O](4+) generated from [Ru(II)(NCN-Me)(bpy)(H2O)](PF6)2 (where NCN-Me is the neutral N-methyl-3,5-di(2-pyridyl)pyridinium iodide after deprotonation of the C-H bond) play a selective role in the C-H bond oxidation of 2-(pyridin-2-yl)-9,10-dihydroacridine (PADHH) and water oxidation, respectively.