Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

: The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

We report on the fabrication and properties of the semiconducting 2D (CH3(CH2)3NH3)2(CH3NH3)n–1PbnI3n+1 (n = 1, 2, 3, and 4) perovskite thin films. The band gaps of the series decrease with increasing n values, from 2.24 eV (CH3(CH2)3NH3)2PbI4 (n = 1) to 1.52 eV CH3NH3PbI3 (n = ∞). The compounds exhibit strong light absorption in the visible region, accompanied by strong photoluminescence at room temperature, rendering them promising light absorbers for photovoltaic applications. Moreover, we find that thin films of the semi-2D perovskites display an ultrahigh surface coverage as a result of the unusual film self-assembly that orients the [PbnI3n+1]− layers perpendicular to the substrates. We have successfully implemented this 2D perovskite family in solid-state solar cells, and obtained an initial power conversion efficiency of 4.02%, featuring an open-circuit voltage (Voc) of 929 mV and a short-circuit current density (Jsc) of 9.42 mA/cm2 from the n = 3 compound. This result is even more encouraging con...

/pdf/2d-homologous-perovskites-as-light-absorbing-materials-for-2ff0fsfqxz.pdf

2D Homologous Perovskites as Light-Absorbing Materials for Solar Cell Applications

The hybrid two-dimensional (2D) halide perovskites have recently drawn significant interest because they can serve as excellent photoabsorbers in perovskite solar cells. Here we present the large scale synthesis, crystal structure, and optical characterization of the 2D (CH3(CH2)3NH3)2(CH3NH3)n−1PbnI3n+1 (n = 1, 2, 3, 4, ∞) perovskites, a family of layered compounds with tunable semiconductor characteristics. These materials consist of well-defined inorganic perovskite layers intercalated with bulky butylammonium cations that act as spacers between these fragments, adopting the crystal structure of the Ruddlesden–Popper type. We find that the perovskite thickness (n) can be synthetically controlled by adjusting the ratio between the spacer cation and the small organic cation, thus allowing the isolation of compounds in pure form and large scale. The orthorhombic crystal structures of (CH3(CH2)3NH3)2(CH3NH3)Pb2I7 (n = 2, Cc2m; a = 8.9470(4), b = 39.347(2) A, c = 8.8589(6)), (CH3(CH2)3NH3)2(CH3NH3)2Pb3I10 (...

http://pubs.acs.org/doi/pdf/10.1021/acs.chemmater.6b00847

Ruddlesden-Popper Hybrid Lead Iodide Perovskite 2D Homologous Semiconductors

Hydrogen fuel is considered as the cleanest renewable resource and the primary alternative to fossil fuels for future energy supply. Sustainable hydrogen generation is the major prerequisite to realize future hydrogen economy. The electrocatalytic hydrogen evolution reaction (HER), as the vital step of water electrolysis to H2 production, has been the subject of extensive study over the past decades. In this comprehensive review, we first summarize the fundamentals of HER and review the recent state-of-the-art advances in the low-cost and high-performance catalysts based on noble and non-noble metals, as well as metal-free HER electrocatalysts. We systemically discuss the insights into the relationship among the catalytic activity, morphology, structure, composition, and synthetic method. Strategies for developing an effective catalyst, including increasing the intrinsic activity of active sites and/or increasing the number of active sites, are summarized and highlighted. Finally, the challenges, perspectives, and research directions of HER electrocatalysis are featured.

Recent Advances in Electrocatalytic Hydrogen Evolution Using Nanoparticles.

Reduction of CO2 to Chemicals and Fuels: A Solution to Global Warming and Energy Crisis

Catalytic conversion of CO2 to chemicals and fuels is a “two birds, one stone” approach toward solving the climate change problem and energy demand–supply deficit in the modern world. Recent advances in mechanistic insights and design of suitable catalysts for direct thermocatalytic hydrogenation of CO2 to C1 products are thoroughly discussed in this Review. The role of catalyst composition and process conditions in determining the selective pathways to various products like carbon monoxide, methanol, methane, and dimethyl ether has been overviewed in light of thermodynamic and kinetic considerations. After extensive elaboration of the main motivation of the reaction pathways, catalytic roles, and reaction thermodynamics, we summarize the most important macroscopic aspects of CO2 hydrogenation technology development, which include reactor innovations, industrial status of the technology, life cycle assessment and technoeconomic analysis. Finally, a critical perspective on the future challenges and opportu...

Thermochemical CO2 Hydrogenation to Single Carbon Products: Scientific and Technological Challenges

The most essential prerequisite for the hydrogen economy is sustainable hydrogen production. The electrochemical hydrogen evolution reaction is a well-studied electrochemical reaction which involves the reduction of protons for hydrogen production. It requires highly efficient and robust catalysts to lower the overpotential and energy consumption. Platinum (Pt) remains the first choice among electrocatalysts because of its excellent activity and high current density. Since Pt is limited by its high cost and scarcity, extensive research is devoted for the development of non-Pt-based cost-effective electrocatalysts. According to the volcano plot, palladium (Pd) can be used as a substitute for Pt towards the hydrogen evolution reaction (HER). Herein, we review various Pd-based electrocatalysts in the form of nanoparticles, alloys, bimetallics and intermetallics reported for the HER. In this review we have emphasized various synthesis techniques employed for these electrocatalysts and the strategies used for improving the catalytic performance. We conclude with a perspective on the future aspects of electrocatalysts based on Pd.

An overview on Pd-based electrocatalysts for the hydrogen evolution reaction

John Androulakis , Sebastian C. Peter , Hao Li , Christos D. Malliakas , John A. Peters , Zhifu Liu , Bruce W W. essels , Jung-Hwan Song , Hosub Jin , Arthur J. reeman , F and Mercouri G. Kanatzidis *

Dimensional Reduction: A Design Tool for New Radiation Detection Materials

A [2 + 2] Schiff base type condensation between 5,10,15,20-tetrakis(4-aminophenyl)porphyrin (TAP) and 1,3,6,8-tetrakis (4-formylphenyl) pyrene (TFFPy) under solvothermal condition yields a crystalline, quasi-two-dimensional covalent organic framework (SB-PORPy-COF). The porphyrin and pyrene units are alternatively occupied in the vertex of 3D triclinic crystal having permanent microporosity with moderately high surface area (∼869 m2 g–1) and promising chemical stability. The AA stacking of the monolayers give a pyrene bridged conducting channel. SB-PORPy-COF has been exploited for metal free hydrogen production to understand the electrochemical behavior using the imine based docking site in acidic media. SB-PORPy-COF has shown the onset potential of 50 mV and the Tafel slope of 116 mV dec–1. We expect that the addendum of the imine based COF would not only enrich the structural variety but also help to understand the electrochemical behavior of these class of materials.

/pdf/electrochemical-stimuli-driven-facile-metal-free-hydrogen-38r3428v5l.pdf

Sebastian C. Peter

Papers

Reduction of CO2 to Chemicals and Fuels: A Solution to Global Warming and Energy Crisis

Thermochemical CO2 Hydrogenation to Single Carbon Products: Scientific and Technological Challenges

An overview on Pd-based electrocatalysts for the hydrogen evolution reaction

Dimensional Reduction: A Design Tool for New Radiation Detection Materials

Electrochemical Stimuli-Driven Facile Metal-Free Hydrogen Evolution from Pyrene-Porphyrin-Based Crystalline Covalent Organic Framework