Visible light-driven H2 production over highly dispersed Ruthenia on Rutile TiO2 nanorods

The immobilization of miniscule quantities of RuO2 (~0.1%) onto one-dimensional (1D) TiO2 nanorods (NRs) allows H2 evolution from water under visible light irradiation. Rod-like rutile TiO2 structures, exposing preferentially (110) surfaces, are shown to be critical for the deposition of RuO2 to enable photocatalytic activity in the visible region. The superior performance is rationalized on the basis of fundamental experimental studies and theoretical calculations, demonstrating that RuO2(110) grown as 1D nanowires on rutile TiO2(110), which occurs only at extremely low loads of RuO2, leads to the formation of a heterointerface that efficiently adsorbs visible light. The surface defects, band gap narrowing, visible photoresponse, and favorable upward band bending at the heterointerface drastically facilitate the transfer and separation of photogenerated charge carriers.Peer ReviewedPostprint (published version

Water Formation Reaction under Interfacial Confinement: Al0.25Si0.75O2 on O-Ru(0001)

Confined nanosized spaces at the interface between a metal and a seemingly inert material, such as a silicate, have recently been shown to influence the chemistry at the metal surface. In prior work, we observed that a bilayer (BL) silica on Ru(0001) can change the reaction pathway of the water formation reaction (WFR) near room temperature when compared to the bare metal. In this work, we looked at the effect of doping the silicate with Al, resulting in a stoichiometry of AlSiO . We investigated the kinetics of WFR at elevated H pressures and various temperatures under interfacial confinement using ambient pressure X-ray photoelectron spectroscopy. The apparent activation energy was lower than that on bare Ru(0001) but higher than that on the BL-silica/Ru(0001). The apparent reaction order with respect to H was also determined. The increased residence time of water at the surface, resulting from the presence of the BL-aluminosilicate (and its subsequent electrostatic stabilization), favors the so-called disproportionation reaction pathway (*HO + *O ↔ 2 *OH), but with a higher energy barrier than for pure BL-silica.Research was carried out in part at the 23-ID-2 (IOS) beamline of the National Synchrotron Light Source II and the Center for Functional Nanomaterials, which are U.S. DOE Office of Science Facilities, and the Scientific Data and Computing Center, a component of the Computational Science Initiative, at Brookhaven National Laboratory under Contract No. DE-SC0012704. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. J.C. thanks the Spanish Ministry of Science, Innovation and Universities for a “Severo Ochoa” grant (BES-2015-075748) through “Severo Ochoa” Excellence Programme (SEV-2016-0683). Z.D. is supported by ACS PRF grant #61059-ND5

Low pressure CO2 hydrogenation to methanol over gold nanoparticles activated on a CeOx/TiO2 Interface

Capture and recycling of CO2 into valuable chemicals such as alcohols could help mitigate its emissions into the atmosphere. Due to its inert nature, the activation of CO2 is a critical step in improving the overall reaction kinetics during its chemical conversion. Although pure gold is an inert noble metal and cannot catalyze hydrogenation reactions, it can be activated when deposited as nanoparticles on the appropriate oxide support. In this combined experimental and theoretical study, it is shown that an electronic polarization at the metal-oxide interface of Au nanoparticles anchored and stabilized on a CeOx/TiO2 substrate generates active centers for CO2 adsorption and its low pressure hydrogenation, leading to a higher selectivity toward methanol. This study illustrates the importance of localized electronic properties and structure in catalysis for achieving higher alcohol selectivity from CO2 hydrogenation.U.S. Department of Energy DE-AC02- 98CH10886, DE-AC02-05CH11231Brookhaven National Laboratory DE-SC001270

Jugar es Jugarse. Trabajos comunitarios con niñxs y adultxs en una villa cordillerana mendocina

Realizamos un proyecto de extensión universitaria aprobado por el Programa “Mauricio López” de la UNCuyo. Ejecución en un año entre marzo y noviembre del 2012 y cuenta con financiamiento.  El objetivo principal es el trabajo comunitario en una villa cordillerana de la provincia de Mendoza. El trabajo se realiza sobre la base de la reflexión comunitaria y el aprendizaje mutuo, en el paradigma de la educación popular latinoamericana,  básicamente en dos líneas: la primera con actividades lúdicas con niñxs y la segunda en la participación con vecinxs organizados de la villa. Realizamos encuentros quincenales con niñxs y vecinxs de la localidad de Villa Cacheuta en el Departamento de Luján de Cuyo, provincia de Mendoza. La Villa se encuentra en la precordillera central, a 35 km de la ciudad de Mendoza. A pesar de su relativa cercanía se encuentra aislada de los centros urbanos. No cuenta con instituciones educativas, cuenta con un servicio muy básico de salud y con medios de transporte público con escasa frecuencia. En la Villa viven 60 familias y más de 50 chicxs en edad escolar. El grupo trabaja desde la perspectiva y metodología propia de la Educación Popular y de la Investigación-Acción Participativa, buscando realizar actividades planificadas y propuestas por los extensionistas y lxs niñxs. El trabajo participativo pretende incorporar contenidos no abordados en la educación formal, tendiendo al equilibrio con la naturaleza, el trabajo comunitario y al conocimiento del espacio propio. Desde los extensionistas se pretende aprender y recuperar conocimientos de la comunidad. Los talleres con lxs niñxs tienen como eje actividades de tipo lúdicas, recreativas, y artísticas para desarrollar  el conocimiento y reflexión crítica en relación al medio donde viven, y su contexto sociocultural. Se basan fundamentalmente en juegos y rondas participativas sobre temáticas propias del lugar: leyendas,  narraciones populares, representaciones teatrales, murgas, juegos colectivos, películas, entre otros.  Al mismo tiempo, en instancias diferentes, se busca promover un espacio de contención, integración y socialización de lxs vecinxs, donde se visibilice la importancia de la labor comunitaria, el trabajo en equipo, y se despierte la inquietud sobre la situación de vulnerabilidad de lxs chicxs. Se aborda la necesidad de recuperar el espacio público, el diálogo y la participación inter-generacional. El equipo extensionista está compuesto por 14 personas: un docente, una graduada y 11 estudiantes, principalmente de la Facultad de Ciencias Políticas y Sociales. Se trabaja con reuniones semanales de autoevaluación y planificación de próximas actividades.

The kinetics of ethylidyne formation from ethylene on Pd(111)

Recent density functional theory (DFT) calculations of the activation energy for the conversion of ethylene to ethylidyne on Pd(111) (Moskaleva, L. V.; Chen, Z.-X.; Aleksandrov, H. A.; Mohammed, A. B.; Sun, Q.; Rösch, N. J. Phys. Chem. C 2009, 113, 2515) predicted an activation barrier with respect to gas-phase ethylene of ∼46 kJ/mol, substantially lower than the results of previous DFT calculations. Thus, the kinetics of formation of ethylidyne from ethylene on Pd(111) are measured as a function of sample temperature using reflection-absorption infrared spectroscopy to monitor the ethylidyne coverage as a function of time. The results yield an experimental value of the height of the activation barrier with respect to gas-phase ethylene of 49 ± 5 kJ/mol, in good agreement with the results of the DFT calculations. The agreement between experiment and theory indicates that the proposed ethylidyne formation pathway involving an initial, ratelimiting ethylene dehydrogenation step to form vinyl species that finally form ethylidyne via an ethylidene intermediate is correct. © 2009 American Chemical Society