On-going and future research at the Sulcis site in Sardinia, Italy. Characterization and experimentation at a possible future CCS pilot

National Italian funding has recently been allocated for the construction of a 350 MWe coal-fired power plant / CCS demonstration plant in the Sulcis area of SW Sardinia, Italy. In addition, the recently approved EC-funded ENOS project (ENabling Onshore CO2 Storage in Europe) will use the Sulcis site as one of its main field research laboratories. Site characterization is already ongoing, and work has begun to design gas injection experiments at 100-200 m depth in a fault. This article gives an overview of results to date and plans for the future from the Sapienza University of Rome research group

Epitaxial growth of AgCrSe2 thin films by molecular beam epitaxy

Funding: The authors gratefully acknowledge the European Research Council (through the QUESTDO project, 714193) and The Leverhulme Trust (Grant No. RL-2016-006) for support. The MBE growth facility was funded through an EPSRC strategic equipment grant: EP/M023958/1. The research leading to this result has been supported by the project CALIPSO under Grant Agreement 312284 from the EU Seventh Framework Programme (FP7/2007-2013).AgCrSe2 exhibits remarkably high ionic conduction, an inversion symmetry-breaking structural transition, and is host to complex non-colinear magnetic orders. Despite its attractive physical and chemical properties, and its potential for technological applications, studies of this compound to date are focused almost exclusively on bulk samples. Here, we report the growth of AgCrSe2 thin films via molecular beam epitaxy. Single-orientated epitaxial growth was confirmed by X-ray diffraction, while resonant photoemission spectroscopy measurements indicate a consistent electronic structure as compared to bulk single crystals. We further demonstrate significant flexibility of the grain morphology and cation stoichiometry of this compound via control of the growth parameters, paving the way for the targeted engineering of the electronic and chemical properties of AgCrSe2 in thin-film form.Publisher PDFPeer reviewe

Preliminary results of geological characterization and geochemical monitoring of Sulcis Basin (Sardinia), as a potential CCS site

The Sulcis Basin is an area situated in SW Sardinia (Italy) and is a potential site for the development of CCS in Italy. This paper illustrates the preliminary results of geological characterization of fractured carbonate reservoir (Miliolitico Fm.) and the sealing sequence, composed by clay, marl and volcanic rocks, with a total thickness of more than 900 m. To characterize the reservoircaprock system an extensive structural-geological survey at the outcrop was conducted. It was also performed a study of the geochemical monitoring, to define the baseline conditions, measuring CO2 concentrations and flux in the study site

Making the Communication of CCS more "human"

CCS communication has proven a tough challenge, particularly for the difficulty in raising interest for the technology, which is still unknown to the majority of the population, and for the complexity of conveying information about its potential for reducing emissions. In this paper we present a research based effort for bringing CCS nearer to people, through visual material developed taking into account emotional needs related to the technology. The production of a short introductory film on CCS is illustrated and its testing with a sample of 700 high school students

Fast Coprecipitation of Calcium Phosphate Nanoparticles inside Gelatin Nanofibers by Tricoaxial Electrospinning

We present an effective method for fabricating electrospun gelatin nanofibers containing well-dispersed inorganic nanoparticles. The new method encompasses the use of a special triaxial needle where mixing calcium and phosphate aqueous solutions in an intermediate needle yield calcium phosphate (CaP) nanoparticles that immediately after precipitation are dragged by the outer polymeric solution and incorporated directly in the electrospinning jet, before nanofiber formation. Gelatin electrospun mats containing different amounts of CaP nanoparticles were prepared and characterized by SEM, TEM, TGA, and stress-strain measurements. The results demonstrate that CaP particles having diameter of few tens of nanometers were successfully introduced in the gelatin nanofibers during the electrospinning process and that they were well dispersed throughout the fiber length. In addition, the use of the special triaxial needle enabled modulating the CaP amount in the nanofibers

Cap rock efficiency of geothermal systems in fold-and-thrust belts:evidence from paleo-thermal and structural analyses in Rosario de La Frontera geothermal area (NW Argentina)

Cap rock characterization of geothermal systems is often neglected despite fracturing may reduce its efficiency and favours fluid migration. We investigated the siliciclastic cap rock of Rosario de La Frontera geothermal system (NW Argentina) in order to assess its quality as a function of fracture patterns and related thermal alteration. Paleothermal investigations (XRD on fine-grained fraction of sediments, organic matter optical analysis and fluid inclusions on veins) and 1D thermal modelling allowed us to distinguish the thermal fingerprint associated to sedimentary burial from that related to fluid migration. The geothermal system is hosted in a Neogene N-S anticline dissected by high angle NNW- and ENE-striking faults. Its cap rock can be grouped into two quality categories: ● rocks acting as good insulators deformed by NNW–SSE and E–W shear fractures, NNE-SSW gypsum- and N-S striking calcite-filled veins formed during the initial stage of anticline growth. Maximum paleo-temperatures (<60°C) were experienced during deposition to folding phases. ● rocks acting as bad insulators deformed by NNW-SSE fault planes and NNW- and WNW-striking sets of fractures associated to late transpressive kinematics. Maximum paleo-temperatures higher than about 115°C are linked to fluid migration from the reservoir to surface (with a reservoir top at maximum depths of 2.5 km) along fault damage zones. This multi-method approach turn out to be particularly useful to trace the main pathways of hot fluids and can be applied in blind geothermal systems where either subsurface data are scarce or surface thermal anomalies are lacking

Direct-ARPES and STM investigation of FeSe thin film growth by Nd:YAG laser

Funding: D.M. acknowledges the receipt of a fellowship from the ICTP Programme for Training and Research in Italian Laboratories, Trieste, Italy. R.A. and A.B. acknowledges the support by the Austrian Science Fund (FWF) through Projects No. P26830, No. P31423 and H2020 NFFA-Europe 654360.Research on ultrathin quantum materials requires full control of the growth and surface quality of the specimens in order to perform experiments on their atomic structure and electron states leading to ultimate analysis of their intrinsic properties. We report results on epitaxial FeSe thin films grown by pulsed laser deposition (PLD) on CaF2 (001) substrates as obtained by exploiting the advantages of an all-in-situ ultra-high vacuum (UHV) laboratory allowing for direct high-resolution surface analysis by scanning tunnelling microscopy (STM), synchrotron radiation X-ray photoelectron spectroscopy (XPS) and angle-resolved photoemission spectroscopy (ARPES) on fresh surfaces. FeSe PLD growth protocols were fine-tuned by optimizing target-to-substrate distance d and ablation frequency, atomically flat terraces with unit-cell step heights are obtained, overcoming the spiral morphology often observed by others. In-situ ARPES with linearly polarized horizontal and vertical radiation shows hole-like and electron-like pockets at the Γ and M points of the Fermi surface, consistent with previous observations on cleaved single crystal surfaces. The control achieved in growing quantum materials with volatile elements such as Se by in-situ PLD makes it possible to address the fine analysis of the surfaces by in-situ ARPES and XPS. The study opens wide avenues for the PLD based heterostructures as work-bench for the understanding of proximity-driven effects and for the development of prospective devices based on combinations of quantum materials.Publisher PDFPeer reviewe

Controlling the charge density wave transition in single-layer TiTe2xSe2(1−x) alloys by band gap engineering

Funding: We gratefully acknowledge support from the Leverhulme Trust via Grant No. RL-2016-006 and the UK Royal Society. The MBE growth facility was funded through an EPSRC strategic equipment grant: EP/M023958/1.Closing the band gap of a semiconductor, into a semimetallic state, gives a powerful potential route to tune the electronic energy gains that drive collective phases like charge density waves (CDW) and excitonic insulator states. We explore this approach for the controversial CDW material monolayer (ML) TiSe2 by engineering its narrow band gap to the semimetallic limit of ML-TiTe2. Using molecular beam epitaxy, we demonstrate the growth of ML-TiTe2xSe2(1−x) alloys across the entire compositional range, and unveil how the (2 × 2) CDW instability evolves through the normal state semiconductor-semimetal transition via in situ angle-resolved photoemission spectroscopy. Through model electronic structure calculations, we identify how this tunes the relative strength of excitonic and Peierls-like coupling, demonstrating band gap engineering as a powerful method for controlling the microscopic mechanisms underpinning the formation of collective states in two-dimensional materials.Publisher PDFPeer reviewe

Evidence of a 2D Electron Gas in a Single-Unit-Cell of Anatase TiO2 (001)

The formation and the evolution of electronic metallic states localized at the surface, commonly termed 2D electron gas (2DEG), represents a peculiar phenomenon occurring at the surface and interface of many transition metal oxides (TMO). Among TMO, titanium dioxide (TiO2), particularly in its anatase polymorph, stands as a prototypical system for the development of novel applications related to renewable energy, devices and sensors, where understanding the carrier dynamics is of utmost importance. In this study, angle-resolved photo-electron spectroscopy (ARPES) and X-ray absorption spectroscopy (XAS) are used, supported by density functional theory (DFT), to follow the formation and the evolution of the 2DEG in TiO2 thin films. Unlike other TMO systems, it is revealed that, once the anatase fingerprint is present, the 2DEG in TiO2 is robust and stable down to a single-unit-cell, and that the electron filling of the 2DEG increases with thickness and eventually saturates. These results prove that no critical thickness triggers the occurrence of the 2DEG in anatase TiO2 and give insight in formation mechanism of electronic states at the surface of TMO