Electronic states and magnetic structure at the Co3O4 (110) surface: a first principles study

Tricobalt tetraoxide (Co3O4) is an important catalyst and Co3O4(110) is a frequently exposed surface in Co3O4 nanomaterials. We employed Density-functional theory with on-site Coulomb repulsion U term to study the atomic structures, energetics, magnetic and electronic properties of the two possible terminations, A and B, of this surface. These calculations predict A as the stable termination in a wide range of oxygen chemical potentials, consistent with recent experimental observations. The Co3+ ions do not have a magnetic moment in the bulk, but become magnetic at the surface, which leads to surface magnetic orderings different from the one in the bulk. Surface electronic states are present in the lower half of the bulk band gap and cause partial metallization of both surface terminations. These states are responsible for the charge compensation mechanism stabilizing both polar terminations. The computed critical thickness for polarity compensation is 4 layers

Solvent Effects on the Adsorption Geometry and Electronic Structure of Dye-Sensitized TiO2: A First-Principles Investigation

The performance of dye-sensitized solar cells (DSSCs) depends significantly on the adsorption geometry of the dye on the semiconductor surface. In turn, the stability and geometry of the adsorbed molecules is influenced by the chemical environment at the electrolyte/ dye/TiO2 interface. To gain insight into the effect of the solvent on the adsorption geometries and electronic properties of dye-sensitized TiO2 interfaces, we carried out first-principles calculations on organic dyes and solvent (water or acetonitrile) molecules coadsorbed on the (101) surface of anatase TiO2. Solvent molecules introduce important modifications on the dye adsorption geometry with respect to the geometry calculated in vacuo. In particular, the bonding distance of the dye from the Ti anchoring atoms increases, the adsorption energy decreases, and the two C−O bonds in the carboxylic moieties become more symmetric than in vacuo. Moreover, the adsorbed solvent induces the deprotonation of the dye due to the changing the acid/base properties of the system. Analysis of the electronic structure for the dye-sensitized TiO2 structures in the presence of coadsorbed solvent molecules shows an upward shift in the TiO2 conduction band of 0.2 to 0.5 eV (0.5 to 0.8 eV) in water (acetonitrile). A similar shift is calculated for a solvent monolayer on unsensitized TiO2. The overall picture extracted from our calculations is consistent with an upshift of the conduction band in acetonitrile (2.04 eV vs SCE) relative to water (0.82 eV vs SCE, pH 7), as reported in previous studies on TiO2 flatband potential (Redmond, G.; Fitzmaurice, D. J. Phys. Chem. 1993, 97, 1426−1430) and suggests a relevant role of the solvent in determining the dye− semiconductor interaction and electronic coupling

Design activism: progettare per attivare energie civiche.

Partiamo da due definizioni laterali di design e periferia: • Design come design activism: insieme di approcci, metodi e strumenti per attivare cittadini; • Periferia non in senso spaziale ma come luogo di aggregazione attorno ai conflitti. Il design può servire a risolvere creativamente i conflitti tramite proposte progettuali, per questo vogliamo lavorare al passaggio dall’attivismo di protesta all’attivismo di progetto. Ecco la traccia di lavoro proposta: • Quali sono i territori periferici italiani dove questo sta avvenendo? • Quali sono i temi attorno ai quali stanno confluendo più proposte progettuali (cibo, energia, cultura, mobilità, welfare, spazio pubblico)? • In che maniera abbiamo visto il design entrare in queste forme di attivismo? • Che tipo di comunità si fa interprete di queste forme di attivismo? • Come passare dall’attivazione iniziale a progetti a medio-lungo termine

Ezio Manzini: design per l’innovazione sociale.

Ezio Manzini è uno dei maggiori studiosi italiani e mondiali di design per la sostenibilità, campo nel quale lavora da più di 20 anni. È fondatore di DESIS, un network internazionale su design per l’innovazione sociale e per la sostenibilità. È Honorary Professor al Politecnico di Milano, Chair Professor alla University of the Arts London e attualmente è Guest Professor alla Tongji University – Shanghai e alla Jiangnan University – Wuxi. Il suo ultimo libro è Design, When Everybody Designs. An Introductin to Design for Social Innovation (MIT 2015) Partiamo dalla domanda più ovvia: di cosa parla questo libro? La considerazione di partenza è che, in un mondo in rapida e profonda trasformazione, tutti progettano. Dove “tutti” significa le singole persone, i gruppi, le comunità, le imprese le associazioni, ma anche le istituzioni, le città e intere regioni. E “progettano” significa che tutti questi soggetti individuali e collettivi, volenti o nolenti, sono spinti a mettere in campo delle capacità progettuali per definire e realizzare le loro strategie di vita

First principles study of adsorbed Cu_n (n=1-4) microclusters on MgO(100): structural and electronic properties

We present a density functional study of the structural and electronic properties of small Cu_n (n=1,4) aggregates on defect-free MgO(100). The calculations employ a slab geometry with periodic boundary conditions, supercells with up to 76 atoms, and include full relaxation of the surface layer and of all adsorbed atoms. The preferred adsorption site for a single Cu adatom is on top of an oxygen atom. The adsorption energy and Cu-O distance are E_S-A = 0.99 eV and d_S-A = 2.04 Angstroems using the Perdew-Wang gradient corrected exchange correlation functional. The saddle point for surface diffusion is at the "hollow" site, with a diffusion barrier of around 0.45 eV. For the adsorbed copper dimer, two geometries, one parallel and one perpendicular to the surface, are very close in energy. For the adsorbed Cu_3, a linear configuration is preferred to the triangular geometry. As for the tetramer, the most stable adsorbed geometry for Cu_4 is a rhombus. The adsorption energy per Cu atom decreases with increasing the size of the cluster, while the Cu-Cu cohesive energy increases, rapidly becoming more important than the adsorption energy.Comment: Major revision, Latex(2e) document, 23 pages, 11 figures, accepted for publication in J. of Chem. Phys., paper available at http://irrmawww.epfl.ch/vm/vm_wor

Band Alignment in Molecular Devices: Influence of Anchoring Group and Metal Work Function

We present periodic Density Functional Theory calculations of the electronic properties of molecular junctions formed by amine-, and thiol-terminated alkane chains attached to two metal (Au, Ag) electrodes. Based on extensive analysis that includes molecular monolayers of varying densities, we establish a relationship between the alignment of the molecular energy levels and the interface dipoles, which shows that the band alignment (BA) in the limit of long, isolated chains is independent of the link group and can be computed from a reference system of non interacting molecule + metal electrodes. The main difference between the amine and thiol linkers is the effective dipole moment at the contact. This is very large, about 4.5 D, for amine linkers, leading to a strong dependence of the BA on the monolayer density and a slow convergence to the isolated molecule limit. Instead, this convergence is fast for S anchors due to the very small, ~ 0.2 D, effective dipoles at the contacts

Changing The Negative Narrative Of Aging: A Case Study On Sexual Wellness Services For Women In Later Life

The global longevity trend requires a paradigm shift in the design of services related to later life. Traditionally centered on the negative narrative of aging, service interventions have targeted sectoral domains such as assistance and healthcare. In- stead, a silver society demands services for the mainstream market, addressing the desires of individuals who lead fulfilling lives at all ages. This paper examines a case study investigating sexual wellness in women's later life. Service design elevates this marginalized topic in active aging discussions to a common concern in a cultural service as output. The methodology combines ethnographic research and participatory de- sign: it involves interviews and co-design sessions with experts and women in later life. Emphasizing the significance of a participatory process, the study underscores the vir- tuous circle of learning from participants and providing them with tools for reflecting on their life experiences, positioning design as a political and empowering practice

Constelações políticas como ecossistemas de ações de design: explorando três casos de políticas de inovação social na Itália

The article considers social innovation in an eco-systemic perspective, focusing on policies able to foster it and discussing design’s role within them in terms of professional skills and a widespread capability among all social actors involved. To be expressions of an innovative governance, social innovation policies must themselves be innovative and form policy constellations: clusters of initiatives able to interact positively with the socio-technical system on which they seek to impact. The article is specifically devoted to illustrating the notion of policy constellation, discussing three social innovation policies in Italy: ‘Bologna Regulation’, ‘Milan Smart City’ and ‘Bollenti Spiriti’ in Apulia. All three case studies refer to project strategies that lead to the creation of ecosystems of independent (but mutually synergic) initiatives. Until now, expert design has had a sometimes significant, but generally marginal, presence in this field (mostly as strategic design and, to a lesser extent, as service and communication design). This article suggests that this could and should increase in the future. The authors conclude by posing a new question: what holds together the constituent projects in a social innovation policy? A possible hypothesis is that this something is a cultural frame: a vision of the world shared by all the actors involved.Keywords: policy constellation, social innovation, design for social innovation, strategic design, design for services, co-design.O artigo ilustra o conceito de constelação de políticas. Especificamente, considera a inovação social numa perspectiva ecossistêmica, com foco em políticas capazes de promovê-la, e discute o papel do design em termos de competências profissionais e de uma capacidade difusa entre todos os atores sociais envolvidos. Para ser expressões de uma governança inovadora, as políticas de inovação social devem ser inovadoras e formar constelações políticas: aglomerados de iniciativas capazes de interagir positivamente com o sistema sociotécnico em que procuram impactar. São discutidas três políticas de inovação social na Itália: “Regulamentação de Bolonha”, “Milan Smart City” e “Bollenti Spiriti” em Puglia. Todos os três estudos de caso referem-se a estratégias de projeto que levam à criação de ecossistemas de iniciativas independentes (mas mutuamente sinérgicas). Até agora, o design profissional tem tido uma presença às vezes significativa, mas geralmente marginal, neste campo (principalmente como design estratégico e, em menor medida, como design de serviços e de comunicação). Este artigo sugere que esta pode e deve aumentar no futuro. Os autores concluem levantando uma nova questão: o que une os projetos constituintes em uma política de inovação social? Uma hipótese possível é que esse algo seja uma moldura cultural: a visão de mundo compartilhada por todos os atores envolvidos.Palavras-chave: constelação de políticas, inovação social, design para inovação social, design estratégico, design de serviços, co-design