Probing the crossover in CO desorption from single crystal to nanoparticulate Ru model catalysts

cited By 10International audienceUsing model catalysts, we demonstrate that CO desorption from Ru surfaces can be switched from that typical of single crystal surfaces to one more characteristic of supported nanoparticles. First, the CO desorption behaviour from Ru nanoparticles supported on highly oriented pyrolytic graphite was studied. Both mass-selected and thermally evaporated nanoparticles were deposited. TPD spectra from the mass-selected nanoparticles exhibit a desorption peak located around 410 K with a broad shoulder extending from around 480 K to 600 K, while spectra obtained from thermally evaporated nanoparticles exhibit a single broad feature from ∼350 K to ∼450 K. A room temperature deposited 50 Å thick Ru film displays a characteristic nanoparticle-like spectrum with a broad desorption feature at ∼420 K and a shoulder extending from ∼450 K to ∼600 K. Subsequent annealing of this film at 900 K produced a polycrystalline morphology of flat Ru(001) terraces separated by monatomic steps. The CO desorption spectrum from this surface resembles that obtained on single crystal Ru(001) with two large desorption features located at 390 K and 450 K due to molecular desorption from terrace sites, and a much smaller peak at ∼530 K due to desorption of dissociatively adsorbed CO at step sites. In a second experiment, ion sputtering was used to create surface defects on a Ru(0 1 54) single crystal surface. A gradual shift away from the desorption spectrum typical of a Ru(001) surface towards one resembling desorption from supported Ru nanoparticles was observed with increasing sputter time. © 2011 the Owner Societies

Advantages of a Polycentric Approach to Climate Change Policy

Lack of progress in global climate negotiations has led scholars to reconsider polycentric approaches to climate policy. Several examples of subglobal mechanisms to reduce greenhouse-gas emissions have been touted, but it remains unclear why they might achieve better climate outcomes than global negotiations alone. Decades of work conducted by researchers associated with the Vincent and Elinor Ostrom Workshop in Political Theory and Policy Analysis at Indiana University have emphasized two chief advantages of polycentric approaches over monocentric ones: they provide more opportunities for experimentation and learning to improve policies over time, and they increase communications and interactions — formal and informal, bilateral and multilateral — among parties to help build the mutual trust needed for increased cooperation. A wealth of theoretical, empirical and experimental evidence supports the polycentric approach

The willingness to pay for a carbon tax in Italy

A carbon tax aimed specifically at the reduction of greenhouse gas (GHG) emissions produced by non-ETS sectors (and in particular, from transportation) has been proposed by policy makers on several occasions but has not yet been implemented in Italy. This paper aims to test the acceptability of such a measure and to quantify its amount by estimating Italian citizens\u2019 willingness to pay (WTP) via two contingent valuation surveys involving a sample of 603 people. We find that the median WTP ranges from \u20ac101 to \u20ac154 if the payment vehicle is an annual fixed carbon tax, and from \u20ac0.17 to \u20ac0.30 per liter if the payment vehicle is a fuel carbon tax. Such values are found to be consistent with the social cost of the GHG emissions produced annually by an Italian citizen. Earmarking the carbon tax either to mitigate the environmental impacts of climate change or to finance renewable energy projects proves to substantially increase the respondents\u2019 WTP. A number of other impacts on the WTP were also estimated, including: respondents\u2019 attitudes and beliefs, their place of residence and mobility habits, and various socioeconomic and demographic characteristics. The policy implications of this evidence are discussed