The materials chemistry research group encourages top-rank post doctoral fellows, both national and international, to apply for the elite Banting and Vanier Canada Graduate Scholarships to support their work in our group.
The applications can be found on the Banting and Vanier websites.
We also encourage Marie-Curie and Alexander von Humbolt fellows as well as other top rank international graduate and post-graduate scholars holding research fellowships to apply for positions in our group.
Congratulations to Geoff for being selected as one of the six finalists for the 2016 World Technology Award!
The full list of finalists can be viewed on The WTN website.
In this work, published in the November 2016 issue of the Proceedings of the National Academy of Sciences, we investigate the role of oxygen vacancy and hydroxide defects on the electronic and photocatalytic properties of In2O3-x(OH)y nanocrystals that have been shown to effectively reduce CO2 to CO via the solar powered reverse water–gas shift reaction CO2 + H2+ hv CO + H2O.
To understand how such defects, affect photogenerated electrons and holes in these nanomaterials, we used transient absorption spectroscopy to study the relaxation dynamics of these nanocrystalscontaining varying concentration of oxygen vacancy and hydroxide defects.
This analysis showed that higher defect concentrations result in longer excited-state lifetimes, which are attributed to improved charge separation and correlate well with the observed trends in the photocatalytic activity.These results are further supported by density-functional theory calculations, which confirm the positions ofoxygen vacancy and hydroxide defect states within the optical band gap of indium oxide.
This enhanced understanding of the role these defects play in determining the optoelectronic properties and charge carrier dynamics can provide valuable insight toward the rational development of more efficient photocatalytic materials for CO2 reduction.
The full article can be viewed on the PNAS website with a subscription.
Professor Ozin has written numerous opinion editorials for Materials Views about hot button issues in nanochemistry. The 55 opinion editorials published so far have been organized by Geoff into a compendium of essays focusing on CO2.
The full compendium of opinion editorials can be viewed here.
In our Advanced Energy Materials 2016 paper, we have successfully synthesized ultra-black TiO2-x nanoparticles for water evaporation by coating and superhydrophobization of them on a stainless steel mesh. Increase of x in TiO2-x resulted in a darker material leading to more efficient solar energy to heat conversion and thus more efficient water evaporation. We believe that the high solar thermal conversion efficiency, low cost, low-toxicity, and good chemical stability make black TiO2-x nanoparticles a potentially useful material for converting solar energy to thermal energy for evaporation of seawater or brackish water in remote and rural areas where access to a centralized drinking water supply is unavailable.
The full article can be read on the Advanced Energy Materials website.
In this work we report for the first time a comparative study of the physical, electronic and photocatalytic properties of all four polymorphs of nanostructured iron oxyhydroxides. In brief, we synthesized all four polymorphs of nanostructured iron oxyhydroxides, namely; goethite (α-FeOOH), akaganeite (β-FeOOH), lepidocrocite (ɣ-FeOOH), and feroxyhyte (δ-FeOOH) and fully characterized them by X-ray diffraction, electron microscopy, UV-Visible spectrophotometry, BET measurements and X-ray photoemission spectroscopy. The relationship between these iron oxyhydroxide polymorphs and their photocatalytic properties were explored by examining the extent of methylene blue (MB) degradation by each polymorph under visible light irradiation. Feroxyhyte exhibited the best photocatalytic properties and degraded 85% of the MB dye in five hours. In comparison, goethite, akaganeite and lepidocrocite degraded only 40%, 35% and 30% of the MB in five hours, respectively. In order to understand this trend, the surface area, particle size and shape, and electronic band properties were systematically studied and discussed. It was found that the rate of MB degradation relates mainly to the surface area of the FeOOH polymorphs more than any other factor. We are deeply indebted to Chenxi Qian for his graphical representation of the artscience encapsulated in our paper.
The full article can be read on the ChemNanoMat website.
Geoff’s latest Materials Views details the cognitive effects CO2 has on humans, referring back to two public health studies done in 2012 and 2015. Reductions in decision-making performance is observed in CO2 levels as low as 1000 ppm which is often exceeded in poorly ventilated rooms. With rapidly accelerating CO2 levels in the atmosphere, the concern for CO2 on public health grows with it.
The full article can be read on the Materials Views website.
Laura Reyes has been featured in a recent ACCN article for her involvement in green chemistry. Her role with the Green Chemistry Initiative (GCI) at UofT and her PhD project focused on investigating how CO2 and H2 interact with the surface of metal oxides are also presented.
The full article can be read on the ACCN website.
The Transformative Research to Combat Climate Change Challenge Workshop will be hosted by UofT on Wednesday October 12. This workshop will focus on converting CO2 to value-added products to enable energy security, environment protection, and climate control.
More information can be found on the information package.
Congratulations to Mireille Ghoussoub for publishing her first paper entitled “Metadynamics-Biased ab Initio Molecular Dynamics Study of Heterogeneous CO2 Reduction via Surface Frustrated Lewis Pairs” in the elite journal ACS Catalysis. Mireille investigated theoretically the effect of temperature on the surface FLP-driven RWGS reaction, CO2 + H2 à CO + H2O. She successfully probed for the first time the mechanism of the RGWS reaction over the defect laden In2O3−x(OH)y surface at finite temperatures of 20 and 180 °C. She was able to map the free energy surfaces for the entire reaction pathway, transition states and locations of energy minima, illustrated in the diagram, to obtain the energetics for the activation of H2 and the capture and reduction of CO2. Her results attest to the interesting types of surface chemistry that can be enabled by FLP surface sites, exemplified in this study by the heterogeneous RWGS reaction.
The full article can be read on the ACS Catalysis website.