High Power Impulse Magnetron Sputtering of CIGS Thin Films for High Efficiency Thin Film Solar Cells

In this work CuIn1-xGaxSe2 (CIGS) thin films with three different values of x (0; 0.28; 1) were preparedby nonreactive sputtering of Cu, In and Ga in HiPIMS (High Power Impulse Magnetron Sputtering) orDC magnetron and subsequently selenized in an Ar+Se atmosphere. Optical emission spectroscopy(OES) was used to monitor some basic plasma parameters during sputtering of metallic precursors. CIGSthin film characteristics were measured using X-ray diffraction (XRD), scanning electron microscopy(SEM), Raman spectroscopy, energy-dispersive X-ray spectroscopy (EDX) and other techniques

Graphene-based metal-organic framework hybrids for applications in catalysis, environmental, and energy technologies

Current energy and environmental challenges demand the development and design of multifunctional porous materials with tunable properties for catalysis, water purification, and energy conversion and storage. Because of their amenability to de novo reticular chemistry, metal-organic frameworks (MOFs) have become key materials in this area. However, their usefulness is often limited by low chemical stability, conductivity and inappropriate pore sizes. Conductive two-dimensional (2D) materials with robust structural skeletons and/or functionalized surfaces can form stabilizing interactions with MOF components, enabling the fabrication of MOF nanocomposites with tunable pore characteristics. Graphene and its functional derivatives are the largest class of 2D materials and possess remarkable compositional versatility, structural diversity, and controllable surface chemistry. Here, we critically review current knowledge concerning the growth, structure, and properties of graphene derivatives, MOFs, and their graphene@MOF composites as well as the associated structure- property-performance relationships. Synthetic strategies for preparing graphene@MOF composites and tuning their properties are also comprehensively reviewed together with their applications in gas storage/separation, water purification, catalysis (organo-, electro-, and photocatalysis), and electrochemical energy storage and conversion. Current challenges in the development of graphene@MOF hybrids and their practical applications are addressed, revealing areas for future investigation. We hope that this review will inspire further exploration of new graphene@MOF hybrids for energy, electronic, biomedical, and photocatalysis applications as well as studies on previously unreported properties of known hybrids to reveal potential "diamonds in the rough".Web of Science12224173381724

Gradient tantalum-doped hematite homojunction photoanode improves both photocurrents and turn-on voltage for solar water splitting

Hematite has a great potential as a photoanode for photoelectrochemical (PEC) water splitting by converting solar energy into hydrogen fuels, but the solar-to-hydrogen conversion efficiency of state-of-the-art hematite photoelectrodes are still far below the values required for practical hydrogen production. Here, we report a core-shell formation of gradient tantalum-doped hematite homojunction nanorods by combination of hydrothermal regrowth strategy and hybrid microwave annealing, which enhances the photocurrent density and reduces the turn-on voltage simultaneously. The unusual bi-functional effects originate from the passivation of the surface states and intrinsic built-in electric field by the homojunction formation. The additional driving force provided by the field can effectively suppress charge???carrier recombination both in the bulk and on the surface of hematite, especially at lower potentials. Moreover, the synthesized homojunction shows a remarkable synergy with NiFe(OH)x cocatalyst with significant additional improvements of photocurrent density and cathodic shift of turn-on voltage. The work has nicely demonstrated multiple collaborative strategies of gradient doping, homojunction formation, and cocatalyst modification, and the concept could shed light on designing and constructing the efficient nanostructures of semiconductor photoelectrodes in the field of solar energy conversion. ?? 2020, The Author(s)

Virtual information systems

The article advocates advantages of 3D virtual information systems and suggests possible techniques for their fast automatic acquisition from range and colour registred images together with solutions for virtual space navigation problems. The proposed system consists of five main parts - range image segmentation, texture analysis, virtual model geometry inference, texture synthesis, and the navigation in virtual environment

African Countries’ Agricultural Trade Value Chain Assessment Case study: Tanzania (Cashew nut exports)

Sub-Saharan Africa lost its status as a net exporter of agricultural products in the early 1980s when prices for raw commodities fell and local production stagnated. Since then, agricultural imports have grown faster than agricultural exports. In order to get to the bottom of this critical issue, UNIDO in partnership with the AU, IFAD, AfDB, FAO, and UNECA, developed the African Agribusiness and Agro-Industries Development Initiative (3ADI). The major objective of the 3ADI is to increase private sector investment flows going into the agriculture sector in Africa by mobilizing resources for agribusiness and agro-industrial development from the domestic, regional or international financial systems. This formed the basis of research with the objective of assessing the value addition chain for some vital agricultural commodities in the 3ADI focus countries. UNIDO is developing several action plans in a few African countries – one of them is Tanzania. In the case of Tanzania, the findings show the potential in cashew nuts. The paper’s main goal is to propose a plan or set of steps leading to the improvement of added value generation in the area of agricultural trade in Tanzania. The paper is focused on one commodity Cashew-nuts. Tanzania boosts high volumes of local supply of this commodity, which is the key prerequisite for the value addition chain through local processing. The results from the analysis prove significant economic losses related to the current structure of Tanzanian trade in cashew nuts. The main problem of the current cashew nut trade activities is the very low added value of exported cashew nuts. The paper analyses the structure of value added activities related to the cashew nut trade and proposes a plan for increasing the share of processed cashew nuts at a much higher unit price in comparison to raw cashew nuts. The simulated development in the cashew sector in Tanzania to the year 2030 is based on two expectations a 5% increase of evaluation of particular steps and a 5% growth of processed cashew nuts export volume resulting in significant growth of export incomes and provides an important material stimulating discussion related to the importance of the transformation of the export structure from unprocessed raw products to processed – finalized products