Dimitriy Vovchok

Three-dimensional ruthenium-doped TiO2 sea urchins for enhanced visible-light-responsive H2 production

Three-dimensional (3D) monodispersed sea urchin-like Ru-doped rutile TiO2 hierarchical architectures composed of radially aligned, densely-packed TiO2 nanorods have been successfully synthesized via an acid-hydrothermal method at low temperature without the assistance of any structure-directing agent and post annealing treatment. The addition of a minuscule concentration of ruthenium dopants remarkably catalyzes the formation of the 3D urchin structure and drives the enhanced photocatalytic H2 production under visible light irradiation, not possible on undoped and bulk rutile TiO2. Increasing ruthenium doping dosage not only increases the surface area up to 166 m(2) g(-1) but also induces enhanced photoresponse in the regime of visible and near infrared light. The doping introduces defect impurity levels, i.e. oxygen vacancy and under-coordinated Ti(3+), significantly below the conduction band of TiO2, and ruthenium species act as electron donors/acceptors that accelerate the photogenerated hole and electron transfer and efficiently suppress the rapid charge recombination, therefore improving the visible-light-driven activity.

Water-gas-shift over metal-free nanocrystalline ceria: An experimental and theoretical study

A tandem experimental and theoretical investigation of a mesoporous ceria catalyst reveals the properties of the metal oxide are conducive for activity typically ascribed to metals, suggesting reduced Ce3+ and oxygen vacancies are responsible for the inherent bi‐functionality of CO oxidation and dissociation of water required for facilitating the production of H2. The degree of reduction of the ceria, specifically the (1 0 0) face, is found to significantly influence the binding of reagents, suggesting reduced surfaces harbor the necessary reactive sites. The metal‐free catalysis of the reaction is significant for catalyst design considerations, and the suite of in situ analyses provides a comprehensive study of the dynamic nature of the high surface area catalyst system. This study postulates feasible improvements in catalytic activity may redirect the purpose of the water‐gas shift reaction from CO purification to primary hydrogen production.