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PRELUDIUM project granted

MSc. Marcin Surówka obtained a grant from National Science Centre within PRELUDIUM 8 programme. The project goal and title are “Charakterystyka spektroskopowa i fotokatalityczna materiałów opartych na tlenku tytanu(IV) modyfikowanych różnymi tlenkami metali”.

Congratulations!

 

Group members

Thesis defended

Tomasz Baran has got his PhD degree. Congratulation!

Photocatalytic reduction of carbon dioxide in hybrid systems

Carbon dioxide utilization may contribute to controlling its atmosphere level, reducing the emission and recycling carbon. Various methods of CO2 reduction are under intensive study, including photocatalysis that is promising, environmentally friendly technique of solar to chemical energy conversion. Three strategies of CO2 reduction to useful chemicals and fuels were investigated: photocatalytic carboxylation of organic compounds with CO2 reducing coupling, photocatalytic CO2 reduction to C1 compounds and bioinspired systems for CO2 reduction to methanol by an enzymatic way with photocatalytic regeneration of coenzyme. Carboxylation of acetylacetone and 2,3-dihydrofuran with carbon dioxide has been performed by using ZnS-based photocatalysts. The formation of carboxylic acid, as proven by 13C NMR, GC-MS and IR, was observed. The reaction efficiency was enhanced after modification of ZnS with ruthenium nanoparticles. The reaction involves one-electron reduction of CO2 to CO2.-with photogenerated electrons from the conduction band of ZnS and one-hole oxidation of organic substrates to the relevant radical. Coupling of formed radicals leads to the formation of carboxylic acids through C-C bound formation. Multielectron CO2 reduction to C1 molecules has been studied using various neat and modified materials: ZnS, CuI, NiO, CuS. HCOOH and CO were found as the main reduction products. The amount and ratio of products were influenced by the type of materials, the presence of deposited ruthenium(0) nanoparticles at the surface of materials and solvent polarity. Last approach of CO2 utilization based on photochemical regeneration of NADH for the enzymatic CO2 to CH3OH reduction through the enzymes cascade: FateDH, FaldDH and ADH. A series of photocatalysts was employed as photocatalyst of reduction of NAD+ to NADH under visible light irradiation. TiO2 photosensitized with organic dye and inorganic chromium complexes, narrow band gap photocatalysts such as Cu2O and InVOas well as ZnS doped with iron or cobalt cations seems to be the most promising photocatalysts. Thorough investigations led to the development of a photocatalytic systems constructed of photocatalyst and electron mediator that yield in selective and efficient regeneration of 1,4-NADH isomer.studied processes can find applications for the solar-light-driven green synthesis of fuels or Cn+1 carboxylic compounds from Csubstrates by utilizing carbon dioxide.

Conference

Upcoming conference

We are pleased to announce that the forthcoming, 21st International Symposium on the Photophysics and Photochemistry of Coordination Compounds will be held in Kraków, 5th-9th July 2015.

Cooperation

Scientific cooperation

The cooperation with Prof. Bunsho Ohtani and Prof. Ewa Kowalska reaches new levels – Wojciech Macyk spends one month as a visiting professor in Catalysis Research Center, Hokkaido University in Sapporo.

Publication

New publication

Our new paper submitted to Dalton Transactions has been selected by the Editors to be announced at the first cover page. The paper entitled “UV and visible light active aqueous titanium dioxide colloids stabilized by surfactants” (Michał Pacia, Piotr Warszyński, Wojciech Macyk; Dalton Trans. 2014, 43, 12480-12485) describes the synthesis and activity of photosensitized titanium dioxides nanoparticles stabilized by micelles formed in the presence of TWEEN® 80 surfactant. The micelles are stable in water at pH = 7, while their structure and size depend on the surface modification of TiO2. The activity towards reactive oxygen species generation induced by visible light, stability at neutral pH in the form of transparent colloids and simple preparation are very promising features of the developed systems.

Group members

Thesis defended

Elżbieta Świętek has got her PhD degree. Congratulation!

Redox Characteristics of Semiconducting Photocatalytic Materials

The aim of the studies was to develop the method based on spectroelectrochemical measurements, which allows for the characterization of redox properties of various types of semiconducting materials, including determination of the impact of structural modification and surface as well as the influence of the experimental conditions on the redox properties of the semiconductors. As a part of this work a concise description of the methods used for characterization of redox properties of semiconducting photocatalytic materials was carried out and a novel model of photoinduced electron transfer in nanocrystalline semiconductor electrodes was proposed. An important part of the dissertation was the elaboration of the spectroelectrochemical method. The extension of the method is based on the application of the reflectance spectroscopy and analysis of the experimental conditions influence on VON values. The determined potentials correspond to the process of electron trapping on the available energy states close to the edge of the conduction band. The influence of several parameters like oxygen concentration, potential sweep rate, pH and the type of electrolyte, were discussed. The developed spectroelectrochemical method was also used for characterisation of the energy states lying close to the edge of the conduction band. Additional energy states of TiO2.(P25), localized within the bandgap, were qualitatively characterized. The applicability of the method to determine deep and shallow electron traps was confirmed. A quantitative analysis of shallow electron traps was also conducted using a modification of the spectroelectrochemical method by designating the distribution of electron density of states for selected samples. A wide range of applications of the new measurement method was discussed on the basis of measurements carried out for different semiconductors.

Publication

New publication

Our newest paper, entitled “Photocatalytic carboxylation of organic substrates with carbon dioxide at zinc sulfide with deposited ruthenium nanoparticles, has been published in ChemPlusChem(Tomasz Baran, Angela Dibenedetto, Michele Aresta, Krzysztof Kruczała, Wojciech Macyk,ChemPlusChem 2014, 79, 708-715). It describes a photocatalytic synthesis of carboxylic acids using CO2 and acetylacetone as substrates in the presence of ZnS-based photocatalysts with deposited ruthenium(0) nanoparticles. The paper has been published in the Early Career Series, the program of ChemPlusChem journal presenting original papers of young scientists nominated by the Editorial Board. Presented studies have been done in cooperation with the group from Bari.

Group meeting

Group trip

To activate not only small molecules, but also minds and bodies, on April 11-12th we enjoyed a trip to Pieniny mountains. We spent two nice days hiking in this beautiful area. (Everybody reached Trzy Korony.)

Equipment

New equipement!

Our group has got a new equipment for advanced photoelectrochemical measurements. The specially designed set-up enables measurements of photocurrents as a function of the electrode potential and wavelength of incident light. In addition, the Kelvin probe can be used to characterize redox properties of studied semiconductors in the dark and upon irradiation with monochromatic light.