Morphology and reactivity of size-selected titanium oxide nanoclusters on Au(111).

The morphology and reactivity of mass-selected titania clusters, Ti3O6 and Ti3O5, deposited onto Au(111) were studied by scanning tunneling microscopy and temperature programmed desorption. Despite differing by only one oxygen atom, the stoichiometric Ti3O6 and the sub-stoichiometric ("reduced") Ti3O5 clusters exhibit very different structures and preferred binding sites. The Ti3O6 clusters bind at step edges and form small assemblies (2-4 clusters) on Au terraces, while the "reduced" Ti3O5 clusters form much larger fractal-like assemblies that can extend across step boundaries. Annealing the Ti3O5,6/Au(111) systems to higher temperatures causes changes in the size-distributions of cluster assemblies, but does not lead to the formation of TiOx nanoislands for temperatures ≤700 K. Reactivity studies show that the reduced Ti3O5 cluster has higher activity than Ti3O6 for 2-propanol dehydration, although both clusters exhibit substantial activity for dehydrogenation to acetone. Calculations using DFT+U suggest that the differences in aggregate morphology and reactivity are associated with the number of undercoordinated Ti3c sites in the supported clusters

Potassium-chemical synthesis of 3D graphene from CO2 and its excellent performance in HTM-free perovskite solar cells

The conversion of greenhouse gas CO2 into novel materials is the most promising approach to solve greenhouse gas issues. Herein, we report for the first time the reaction of potassium with CO2 to synthesize three-dimensional honeycomb-like structured graphene (3DHG). Furthermore, 3DHG exhibited excellent performance as a counter electrode for hole transport material (HTM)-free perovskite solar cells, leading to a power conversion efficiency of 10.06%. This work constitutes a new aspect of potassium chemistry for material synthesis from a greenhouse gas and the generation of electrical energy from sunlight.Fil: Wei, Wei. Michigan Technological University; Estados UnidosFil: Hu, Baoyun. Tongji University; ChinaFil: Jin, Fangming. Shanghai Jiao Tong University; ChinaFil: Jing, Zhenzi. Tongji University; ChinaFil: Li, Yuexiang. Nanchang University; ChinaFil: Garcia Blanco, Andres Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada ; ArgentinaFil: Stacchiola, Dario Jose. Brookhaven National Laboratory; Estados UnidosFil: Hu, Yun Hang. Michigan Technological University; Estados Unido

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

Adsorption of hydrogen on the surface and sub-surface of Cu(111)

The interaction of atomic hydrogen with the Cu(111) surface was studied by a combined experimental-theoretical approach, using infrared reflection absorption spectroscopy, temperature programmed desorption, and density functional theory (DFT). Adsorption of atomic hydrogen at 160 K is characterized by an anti-absorption mode at 754 cm−1 and a broadband absorption in the IRRA spectra, related to adsorption of hydrogen on three-fold hollow surface sites and sub-surface sites, and the appearance of a sharp vibrational band at 1151 cm−1 at high coverage, which is also associated with hydrogen adsorption on the surface. Annealing the hydrogen covered surface up to 200 K results in the disappearance of this vibrational band. Thermal desorption is characterized by a single feature at ∼295 K, with the leading edge at ~250 K. The disappearance of the sharp Cu-H vibrational band suggests that with increasing temperature the surface hydrogen migrates to sub-surface sites prior to desorption from the surface. The presence of sub-surface hydrogen after annealing to 200 K is further demonstrated by using CO as a surface probe. Changes in the Cu-H vibration intensity are observed when cooling the adsorbed hydrogen at 180 K to 110 K, implying the migration of hydrogen. DFT calculations show that the most stable position for hydrogen adsorption on Cu(111) is on hollow surface sites, but that hydrogen can be trapped in the second sub-surface layer.Fil: Mudiyanselage, Kumudu. Brookhaven National Laboratory; Estados UnidosFil: Yang, Yixiong. State University Of New York; Estados UnidosFil: Hoffmann, Friedrich M.. City University Of New York; Estados UnidosFil: Furlong, Octavio Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Física Aplicada; ArgentinaFil: Hrbek, Jan. Brookhaven National Laboratory; Estados UnidosFil: White, Michael G.. Brookhaven National Laboratory; Estados UnidosFil: Liu, Ping. Brookhaven National Laboratory; Estados UnidosFil: Stacchiola, Dario Jose. Brookhaven National Laboratory; Estados Unido

High catalytic activity of Au/CeO x/TiO 2(110) controlled by the nature of the mixed-metal oxide at the nanometer level

Mixed-metal oxides play a very important role in many areas of chemistry, physics, materials science, and geochemistry. Recently, there has been a strong interest in understanding phenomena associated with the deposition of oxide nanoparticles on the surface of a second (host) oxide. Here, scanning tunneling microscopy, photoemission, and density-functional calculations are used to study the behavior of ceria nanoparticles deposited on a TiO2(110) surface. The titania substrate imposes nontypical coordination modes on the ceria nanoparticles. In the CeO x/TiO 2(110) systems, the Ce cations adopt an structural geometry and an oxidation state (+3) that are quite different from those seen in bulk ceria or for ceria nanoparticles deposited on metal substrates. The increase in the stability of the Ce 3+ oxidation state leads to an enhancement in the chemical and catalytic activity of the ceria nanoparticles. The codeposition of ceria and gold nanoparticles on a TiO 2(110) substrate generates catalysts with an extremely high activity for the production of hydrogen through the water-gas shift reaction (H 2O + CO → H 2 + CO 2) or for the oxidation of carbon monoxide (2C0 + O 2→2CO 2). The enhanced stability of the Ce 3+ state is an example of structural promotion in catalysis described here on the atomic level. The exploration of mixed-metal oxides at the nanometer level may open avenues for optimizing catalysts through stabilization of unconventional surface structures with special chemical activity.Ministerio de Ciencia e Innovación MAT2008-0491

Y ahí es cuando empiezo a elegir la política : trayectorias de jóvenes militantes en la provincia de Mendoza

En esta ponencia nos interesa, particularmente, abordar el asunto de las militancias juveniles. Con frecuencia suelen concebirse los mecanismos de adiestramiento ideológico o de formación política de las organizaciones como la única vía de acceso a la explicación de los compromisos militantes. Desde una visión contraria a aquellos discursos, buscaremos interpretar las disposiciones subjetivas que orientan los compromisos asumidos por los/as jóvenes. Consideramos que la adhesión a un colectivo o a una causa común esta tamizada por una serie de vivencias individuales y colectivas que moldean las identificaciones políticas. Si bien el activismo militante involucra distintas aristas, ahondaremos en dos dimensiones: por un lado, la relación entre los atributos sociales y el oficio político y, por otro lado, sobre el desarrollo de las carreras militantes. Para ello, desde un enfoque cualitativo, indagaremos las trayectorias militantes de los/as referentes de las ramas juveniles de tres partidos políticos de la provincia de Mendoza: la Unión Cívica Radical (Juventud Radical), el Partido Justicialista (Juventud Peronista) y el Partido de los Trabajadores Socialistas (Juventud del Partido de los Trabajadores Socialistas). Los insumos para este trabajo provienen de entrevistas a los/as tres referentes de las juventudes partidarias señaladas, realizadas en 2017 y 2018.Fil: Stacchiola, Octavio. CONICET (Consejo Nacional de Investigaciones Científicas y Técnicas) - Universidad Nacional de Cuyo

El arte y la constitución de un sujeto emancipado

El presente artículo tiene como objetivo poner en cuestión algunas de las nociones analíticas que nutren actualmente el debate vinculado a la relación entre el universo de las expresiones artísticas y el campo de lo político. Con la inauguración de una nueva ´época –la postmodernidad– dicha controversia asumió ciertas particularidades. Para complejizar esta discusión, los valiosos aportes teóricos vertidos por Jacques Ranciere y Franz Hinkelammert nos permitirán introducir una serie de interrogantes acerca de las posibilidades de constitución de un arte crítico y su ligazon con la construcción de un sujeto individual y colectivo potencialmente emancipador

La cátedra de Sociología General como espacio de formación en la Facultad de Ciencias Políticas y Sociales de la UNCuyo

La presente ponencia tiene por objetivo de comunicar algunos avances de lo realizado por el equipo de Investigación Cátedra Investiga: “La Enseñanza de la Sociología: Una aproximación a los espacios curriculares de Sociología en la UNCuyo" 2019-2020 conformado por: Profesores Walter Fabián Noguera, Ana Marcela Ficcardi, Gonzalo Navarro, Mauricio Follari Gorra, Octavio Stacchiola y Verónica Falcón, y Estudiantes: María de los Ángeles Lara, Norma Luciana Videla, Sofía Gómez Mansur, Pedro Fernández. Ofreceremos en el escrito lo objetivado y analizado sobre las prácticas de enseñanza, contenidos y dispositivos didácticos, de la cátedra de Sociología General en el periodo 2017 – 2020, espacio curricular de la Licenciatura en Ciencia Política y Administración Pública de la Facultad de Ciencias Políticas y Sociales – UNCuyo.Fil: Ficcardi, Ana Marcela. Universidad Nacional de Cuyo. Facultad de Ciencias Políticas y SocialesFil: Follari Gorra, Mauricio. Universidad Nacional de Cuyo. Facultad de Ciencias Políticas y SocialesFil: Navarro, Gonzalo. Universidad Nacional de Cuyo. Facultad de Ciencias Políticas y SocialesFil: Stacchiola, Octavio. Universidad Nacional de Cuyo. Facultad de Ciencias Políticas y Sociale