Dinuclear Ru-Cu complexes : electronic characterisation and application to dye-sensitised solar cells

Dye-sensitised solar cells have emerged as an important developing technology for low-cost solar energy conversion and a crucial element of these is the dye, responsible for light harvesting and control of interfacial electron-transfer processes.[1] A number of examples of dye exist in the literature which link a ruthenium polypyridyl complex to another platinum group metal complex such as Ru (II), Os (II), Re (I) or Rh (III) via a bridging ligand.[2-6] These systems are often referred to as heterosupramolecular triads when adsorbed on the surface of TiO2 as the semiconductor becomes an active component in the system. A number of problems can arise with these types of sensitisers, for example if a flexible linker, e.g. bis-pyridylethane, is used to couple the two complexes it can be hard to control the orientation of the whole dye. This may lead to the resultant dye cation hole being closer to the surface than desired, and hence the long-lived charge-separated state is not achieved. In addition the size of these dyes may be much larger than that of a mononuclear complex and can lead to poor pore filling on the TiO2 and lower dye coverage, leading to a lower efficiency cell.[7] Despite these issues, efficient charge-separation has been achieved with polynuclear complexes and a long-lived state on the millisecond timescale has been observed for a trinuclear ruthenium complex.[8]

Homo- and heteronuclear meso,meso-(E)-Ethene-1,2-diyl-Linked Diporphyrins : preparation, X-ray crystal structure, electronic absorption and emission spectra and density functional theory calculations

Homo-and heteronuclear meso,meso-(E)-ethene-1,2-diyl-linked diporphyrins have been prepared by the Suzuki coupling of porphyrinylboronates and iodovinylporphyrins. Combinations comprising 5,10,15-triphenylporphyrin (TriPP) on both ends of the ethene-1,2-diyl bridge M 210 (M 2=H 2/Ni, Ni 2, Ni/Zn, H 4, H 2Zn, Zn 2) and 5,15-bis(3,5-di-tert-butylphenyl)porphyrinato-nickel(II) on one end and H 2, Ni, and ZnTriPP on the other (M 211), enable the first studies of this class of compounds possessing intrinsic polarity. The compounds were characterized by electronic absorption and steady state emission spectra, 1H NMR spectra, and for the Ni 2 bis(TriPP) complex Ni 210, single crystal X-ray structure determination. The crystal structure shows ruffled distortions of the porphyrin rings, typical of Ni II porphyrins, and the (E)-C 2H 2 bridge makes a dihedral angle of 50° with the mean planes of the macrocycles. The result is a stepped parallel arrangement of the porphyrin rings. The dihedral angles in the solid state reflect the interplay of steric and electronic effects of the bridge on interporphyrin communication. The emission spectra in particular, suggest energy transfer across the bridge is fast in conformations in which the bridge is nearly coplanar with the rings. Comparisons of the fluorescence behaviour of H 410 and H 2Ni10 show strong quenching of the free base fluorescence when the complex is excited at the lower energy component of the Soret band, a feature associated in the literature with more planar conformations. TDDFT calculations on the gas-phase optimized geometry of Ni 210 reproduce the features of the experimental electronic absorption spectrum within 0.1 eV. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

First-principle studies of electronic structure and C-doping effect in boron nitride nanoribbon

Structural and electronic properties have been studied for Boron Nitride nanoribbons (BNNR) with both zigzag and armchair shaped edge (Z-BNNR and A-BNNR) by first-principle spin-polarized total energy calculations. We found that the energy band gap of Z-BNNR is indirect and decreases monotonically with the increasing ribbon width, whereas direct energy band gap oscillation was observed for A-BNNRs. Additionally, C-substitution at either single boron or nitrogen atom site in BNNRs could induce spontaneous magnetization. Our results could be potentially useful to design magnetic nano-devices based on BNNRs.

Voltammetric monitoring of gold nanoparticle formation facilitated by glycyl-L-tyrosine : relation to electronic spectra and transmission electron microscopy images

Voltammetric techniques have been introduced to monitor the formation of gold nanoparticles produced via the reaction of the amino acid glycyl-L-tyrosine with Au(III) (bromoaurate) in 0.05 M KOH conditions. The alkaline conditions facilitate amino acid binding to Au(III), inhibit the rate of reduction to Au(0), and provide an excellent supporting electrolyte for voltammetric studies. Data obtained revealed that a range of time-dependent gold solution species are involved in gold nanoparticle formation and that the order in which reagents are mixed is critical to the outcome. Concomitantly with voltammetric measurements, the properties of gold nanoparticles formed are probed by examination of electronic spectra in order to understand how the solution environment present during nanoparticle growth affects the final distribution of the nanoparticles. Images obtained by the ex situ transmission electron microscopy (TEM) technique enable the physical properties of the nanoparticles isolated in the solid state to be assessed. Use of this combination of in situ and ex situ techniques provides a versatile framework for elucidating the details of nanoparticle formation.

Effect of doping with Co and/or Cu on electronic structure and optical properties of ZnO

This paper reports on ab initio numerical simulations of the effect of Co and Cu dopings on the electronic structure and optical properties of ZnO, pursued to develop diluted magnetic semiconductors vitally needed for spintronic applications. The simulations are based upon the Perdew-Burke-Enzerh generalized gradient approximation on the density functional theory. It is revealed that the electrons with energies close to the Fermi level effectively transfer only between Cu and Co ions which substitute Zn atoms, and are located in the neighbor sites connected by an O ion. The simulation results are consistent with the experimental observations that addition of Cu helps achieve stable ferromagnetism of Co-doped ZnO. It is shown that simultaneous insertion of Co and Cu atoms leads to smaller energy band gap, redshift of the optical absorption edge, as well as significant changes in the reflectivity, dielectric function, refractive index, and electron energy loss function of ZnO as compared to the doping with either Co or Cu atoms. These highly unusual optical properties are explained in terms of the computed electronic structure and are promising for the development of the next-generation room-temperature ferromagnetic semiconductors for future spintronic devices on the existing semiconductor micromanufacturing platform.

Bioaerosols associated with industrial green waste composting facilities and optimal microbiological indicators

This project developed and assessed a standard operating procedure for monitoring microbiological aerosol levels and dispersal from Australian industrial composting facilities. Development occurred via seasonal monitoring of such operations with evaluation of optimal microbial indicator organisms, sampling and analysis logistics. The resultant procedure allows practical end-user assessment of compost-associated bioaerosol levels, and potential health risks to proximal residential populations encroaching on such composting facilities and on-site industrial operations personnel.

Electronic coupling and catalytic effect on H2 evolution of MoS2/graphene nanocatalyst

Inorganic nano-graphene hybrid materials that are strongly coupled via chemical bonding usually present superior electrochemical performance. However, how the chemical bond forms and the synergistic catalytic mechanism remain fundamental questions. In this study, the chemical bonding of the MoS2 nanolayer supported on vacancy mediated graphene and the hydrogen evolution reaction of this nanocatalyst system were investigated. An obvious reduction of the metallic state of the MoS2 nanolayer is noticed as electrons are transferred to form a strong contact with the reduced graphene support. The missing metallic state associated with the unsaturated atoms at the peripheral sites in turn modifies the hydrogen evolution activity. The easiest evolution path is from the Mo edge sites, with the presence of the graphene resulting in a decrease in the energy barrier from 0.17 to 0.11 eV. Evolution of H2 from the S edge becomes more difficult due to an increase in the energy barrier from 0.43 to 0.84 eV. The clarification of the chemical bonding and catalytic mechanisms for hydrogen evolution using this strongly coupled MoS2/graphene nanocatalyst provide a valuable source of reference and motivation for further investigation for improved hydrogen evolution using chemically active nanocoupled systems.

Electronic and vibrational spectra of gaspeite

Visible, near-infrared, IR and Raman spectra of magnesian gaspeite are presented. Nickel ion is the main source of the electronic bands as it is the principal component in the mineral where as the bands in IR and Raman spectra are due to the vibrational processes in the carbonate ion as an entity. The combination of electronic absorption and vibrational spectra (including near-infrared, FTIR and Raman) of magnesian gaspeite are explained in terms of the cation co-ordination and the behaviour of CO32– anion in the Ni–Mg carbonate. The electronic absorption spectrum consists of three broad and intense bands at 8130, 13160 and 22730 cm–1 due to spin-allowed transitions and two weak bands at 20410 and 30300 cm–1 are assigned to spin-forbidden transitions of Ni2+ in an octahedral symmetry. The crystal field parameters evaluated from the observed bands are Dq = 810; B = 800 and C = 3200 cm–1. The two bands in the near-infrared spectrum at 4330 and 5130 cm–1 are overtone and combination of CO32– vibrational modes. For the carbonate group, infrared bands are observed at 1020 cm–1(1 ), 870 cm–1 (2), 1418 cm–1 (3) and 750 cm–1 (4), of which3, the asymmetric stretching mode is most intense. Three well resolved Raman bands at 1571, 1088 and 331 cm–1 are assigned to 3, 1 and MO stretching vibrations.

Towards ubiquitous city : concept, planning, and experiences in the Republic of Korea

Information and communication technologies (ICTs) had occupied their position on knowledge management and are now evolving towards the era of self-intelligence (Klosterman, 2001). In the 21st century ICTs for urban development and planning are imperative to improve the quality of life and place. This includes the management of traffic, waste, electricity, sewerage and water quality, monitoring fire and crime, conserving renewable resources, and coordinating urban policies and programs for urban planners, civil engineers, and government officers and administrators. The handling of tasks in the field of urban management often requires complex, interdisciplinary knowledge as well as profound technical information. Most of the information has been compiled during the last few years in the form of manuals, reports, databases, and programs. However frequently, the existence of these information and services are either not known or they are not readily available to the people who need them. To provide urban administrators and the public with comprehensive information and services, various ICTs are being developed. In early 1990s Mark Weiser (1993) proposed Ubiquitous Computing project at the Xerox Palo Alto Research Centre in the US. He provides a vision of a built environment which digital networks link individual residents not only to other people but also to goods and services whenever and wherever they need (Mitchell, 1999). Since then the Republic of Korea (ROK) has been continuously developed national strategies for knowledge based urban development (KBUD) through the agenda of Cyber Korea, E-Korea and U-Korea. Among abovementioned agendas particularly the U-Korea agenda aims the convergence of ICTs and urban space for a prosperous urban and economic development. U-Korea strategies create a series of U-cities based on ubiquitous computing and ICTs by a means of providing ubiquitous city (U-city) infrastructure and services in urban space. The goals of U-city development is not only boosting the national economy but also creating value in knowledge based communities. It provides opportunity for both the central and local governments collaborate to U-city project, optimize information utilization, and minimize regional disparities. This chapter introduces the Korean-led U-city concept, planning, design schemes and management policies and discusses the implications of U-city concept in planning for KBUD.

The 3D model of l(IT)eracy and the English curriculum

The field of literacy studies has always been challenged by the changing technologies that humans have used to express, represent and communicate their feelings, ideas, understandings and knowledge. However, while the written word has remained central to literacy processes over a long period, it is generally accepted that there have been significant changes to what constitutes ‘literate’ practice. In particular, the status of the printed word has been challenged by the increasing dominance of the image, along with the multimodal meaning-making systems facilitated by digital media. For example, Gunther Kress and other members of the New London Group have argued that the second half of the twentieth century saw a significant cultural shift from the linguistic to the visual as the dominant semiotic mode. This in turn, they suggest, was accompanied by a cultural shift ‘from page to screen’ as a dominant space of representation (e.g. Cope & Kalantzis, 2000; Kress, 2003; New London Group, 1996). In a similar vein, Bill Green has noted that we have witnessed a shift from the regime of the print apparatus to a regime of the digital electronic apparatus (Lankshear, Snyder and Green, 2000). For these reasons, the field of literacy education has been challenged to find new ways to conceptualise what is meant by ‘literacy’ in the twenty first century and to rethink the conditions under which children might best be taught to be fully literate so that they can operate with agency in today’s world.

Improvement of the statutory framework for construction and demolition waste management exemplified in Germany and Australia

Construction and demolition (C&D) waste occupies the largest share of overall waste generation in many countries. However, waste management practices and outcomes may differ between countries. For instance, in Australia, C&D waste recovery is continuously improving during the last years but the amount of C&D waste increases every year, as there has been little improvement in waste avoidance and minimization. In contrast, in Germany, waste generation remains constant over many years despite the continuous economic growth. The waste recycling rate in Germany is one of the highest in the world. However, most waste recycled is from demolition work rather than from waste generated during new construction. In addition, specific laws need to be developed to further reduce landfill of non-recycled waste. Despite of the differences, C&D waste generation and recovery in both countries depend on the effectiveness of the statutory framework, which regulates their waste management practices. This is an issue in other parts of the world as well. Therefore countries can learn from each other to improve their current statutory framework for C&D waste management. By taking Germany and Australia as an example, possible measures to improve current practices of C&D waste management through better statutory tools are identified in this paper. After providing an overview of the statutory framework of both countries and their status in waste generation and recovery, a SWOT analysis is conducted to identify strengths, weaknesses, opportunities and threats of the statutory tools. Recommendations to improve the current statutory frameworks, in order to achieve less waste generation and more waste recovery in the construction industry are provided for the German and Australian government and they can also be transferred to other countries.

A waste management system for small and medium enterprises engaged in office building retrofit projects

Waste management and minimisation is considered to be an important issue for achieving sustainability in the construction industry. Retrofit projects generate less waste than demolitions and new builds, but they possess unique features and require waste management approaches that are different to traditional new builds. With the increasing demand for more energy efficient and environmentally sustainable office spaces, the office building retrofit market is growing in capital cities around Australia with a high level of refurbishment needed for existing aging properties. Restricted site space and uncertain delivery process in these projects make it a major challenge to manage waste effectively. The labour-intensive nature of retrofit projects creates the need for the involvement of small and medium enterprises (SMEs) as subcontractors in on-site works. SMEs are familiar with on-site waste generation but are not as actively motivated and engaged in waste management activities as the stakeholders in other construction projects in the industry. SMEs’ responsibilities for waste management in office building retrofit projects need to be identified and adapted to the work delivery processes and the waste management system supported by project stakeholders. The existing literature provides an understanding of how to manage construction waste that is already generated and how to increase the waste recovery rate for office building retrofit projects. However, previous research has not developed theories or practical solutions that can guide project stakeholders to understand the specific waste generation process and effectively plan for and manage waste in ongoing project works. No appropriate method has been established for the potential role and capability of SMEs to manage and minimise waste from their subcontracting works. This research probes into the characteristics of office building retrofit project delivery with the aim to develop specific tools to manage waste and incorporate SMEs in this process in an appropriate and effective way. Based on an extensive literature review, the research firstly developed a questionnaire survey to identify the critical factors of on-site waste generation in office building retrofit projects. Semi-structured interviews were then utilised to validate the critical waste factors and establish the interrelationships between the factors. The interviews served another important function of identifying the current problems of waste management in the industry and the performance of SMEs in this area. Interviewees’ opinions on remedies to the problems were also collected. On the foundation of the findings from the questionnaire survey and semi-structured interviews, two waste planning and management strategies were identified for the dismantling phase and fit-out phase of office building retrofit projects, respectively. Two models were then established to organize SMEs’ waste management activities, including a work process-based integrated waste planning model for the dismantling phase and a system dynamics model for the fit-out phase. In order to apply the models in real practice, procedures were developed to guide SMEs’ work flow in on-site waste planning and management. In addition, a collaboration framework was established for SMEs and other project stakeholders for effective waste planning and management. Furthermore, an organisational engagement strategy was developed to improve SME waste management practices. Three case studies were conducted to validate and finalise the research deliverables. This research extends the current literature that mostly covers waste management plans in new build projects, by presenting the knowledge and understanding of addressing waste problems in retrofit projects. It provides practical tools and guidance for industry practitioners to effectively manage the waste generation processes in office building retrofit projects. It can also promote industry-level recognition of the role of SMEs and their performance in on-site waste management.

Electronic functionality in graphene-based nanoarchitectures : discovery and design via first-principles modeling

Graphene has promised many novel applications in nanoscale electronics and sustainable energy due to its novel electronic properties. Computational exploration of electronic functionality and how it varies with architecture and doping presently runs ahead of experimental synthesis yet provides insights into types of structures that may prove profitable for targeted experimental synthesis and characterization. We present here a summary of our understanding on the important aspects of dimension, band gap, defect, and interfacial engineering of graphene based on state-of-the-art ab initio approaches. Some most recent experimental achievements relevant for future theoretical exploration are also covered.

Structural and electronic properties of layered arsenic and antimony arsenide

Layered materials exhibit intriguing electronic characteristics and the search for new types of two-dimensional (2D) structures is of importance for future device fabrication. Using state-of-art first principle calculations, we identify and characterize the structural and electronic properties of two 2D layered arsenic materials, namely, arsenic and its alloy AsSb. The stable 2D structural configuration of arsenic is confirmed to be the low-buckled two-dimensional hexagonal structure by phonon and binding energy calculations. The monolayer exhibits indirect semiconducting properties with gap around 1.5 eV (corrected to 2.2 eV by hybrid function), which can be modulated into a direct semiconductor within a small amount of tensile strain. These semiconducting properties are preserved when cutting into 1D nanoribbons, but the band gap is edge dependent. It is interesting to find that an indirect to direct gap transition can be achieved under strain modulation of the armchair ribbon. Essentially the same phenomena can be found in layered AsSb, except a weak Rashba induced band splitting is present in AsSb due to the nonsymmetric structure and spin orbit coupling. When an additional layer is added on the top, a semiconductor–metal transition will occur. The findings here broaden the family of 2D materials beyond graphene and transition metal dichalcogenides and provide useful information for experimental fabrication of new layered materials with possible application in optoelectronics.